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Anorexia nervosa, often referred to simply as anorexia, is an
eating disorder An eating disorder is a mental disorder defined by abnormal eating behaviors that negatively affect a person's physical or mental health. Only one eating disorder can be diagnosed at a given time. Types of eating disorders include binge eating d ...
characterized by low weight, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. ''Anorexia'' is a term of Greek origin: ''an-'' (ἀν-, prefix denoting negation) and ''orexis'' (ὄρεξις, "appetite"), translating literally to "a loss of appetite"; the adjective ''nervosa'' indicating the functional and non-organic nature of the disorder. ''Anorexia nervosa'' was coined by Gull in 1873 but, despite literal translation, the feeling of hunger is frequently present and the pathological control of this instinct is a source of satisfaction for the patients. Individuals with anorexia nervosa have a fear of being
overweight Being overweight or fat is having more body fat than is optimally healthy. Being overweight is especially common where food supplies are plentiful and lifestyles are sedentary. , excess weight reached epidemic proportions globally, with mo ...
or being seen as such, although they are in fact
underweight An underweight person is a person whose body weight is considered too low to be healthy. A person who is underweight is malnourished. Assessment The body mass index, a ratio of a person's weight to their height, has traditionally been used t ...
. The DSM-5 describes this perceptual symptom as "disturbance in the way in which one's body weight or shape is experienced". In
research Research is "creativity, creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular att ...
and clinical settings, this symptom is called "
body image disturbance Body image disturbance (BID) is a common symptom in patients with eating disorders and is characterized by an altered perception of one's own body. The onset is mainly attributed to patients with anorexia nervosa who persistently tend to sub ...
". Individuals with anorexia nervosa also often deny that they have a problem with low weight. They may weigh themselves frequently, eat small amounts, and only eat certain foods. Some exercise excessively, force themselves to
vomit Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenterit ...
(in the "anorexia purging" subtype), or use
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...
s to lose weight and control body shapes, and/or binge eat. Medical complications may include
osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...
,
infertility Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...
, and heart damage, among others. Women will often stop having menstrual periods. In extreme cases, patients with anorexia nervosa who continually refuse significant dietary intake and weight restoration interventions, and are declared incompetent to make decisions by a psychiatrist, may be fed by force under restraint via
nasogastric tube Nasogastric intubation is a medical process involving the insertion of a plastic tube (nasogastric tube or NG tube) through the nose, down the oesophagus, and down into the stomach. Orogastric intubation is a similar process involving the inserti ...
after asking their parents or proxies to make the decision for them. The cause of anorexia is currently unknown. There appear to be some genetic components with
identical twins Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...
more often affected than fraternal twins. Cultural factors also appear to play a role, with societies that value thinness having higher rates of the disease. Additionally, it occurs more commonly among those involved in activities that value thinness, such as high-level athletics, modeling, and dancing. Anorexia often begins following a major life-change or
stress Stress may refer to: Science and medicine * Stress (biology), an organism's response to a stressor such as an environmental condition * Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...
-inducing event. The diagnosis requires a significantly low weight and the severity of disease is based on
body mass index Body mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m2, resulting from mass in kilograms and he ...
(BMI) in adults with mild disease having a BMI of greater than 17, moderate a BMI of 16 to 17, severe a BMI of 15 to 16, and extreme a BMI less than 15. In children, a BMI for age percentile of less than the 5th percentile is often used. Treatment of anorexia involves restoring the patient back to a healthy weight, treating their underlying psychological problems, and addressing behaviors that promote the problem. While medications do not help with weight gain, they may be used to help with associated
anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
or depression. Different therapy methods may be useful, such as
cognitive behavioral therapy Cognitive behavioral therapy (CBT) is a psycho-social intervention that aims to reduce symptoms of various mental health conditions, primarily depression and anxiety disorders. CBT focuses on challenging and changing cognitive distortions (suc ...
or an approach where parents assume responsibility for feeding their child, known as Maudsley family therapy. Sometimes people require admission to a hospital to restore weight. Evidence for benefit from
nasogastric tube Nasogastric intubation is a medical process involving the insertion of a plastic tube (nasogastric tube or NG tube) through the nose, down the oesophagus, and down into the stomach. Orogastric intubation is a similar process involving the inserti ...
feeding is unclear; such an intervention may be highly distressing for both anorexia patients and healthcare staff when administered against the patient's will under restraint. Some people with anorexia will have a single episode and recover while others may have recurring episodes over years. Many complications improve or resolve with the regaining of weight. Globally, anorexia is estimated to affect 2.9 million people . It is estimated to occur in 0.3% to 4.3% of women and 0.2% to 1% of men in Western countries at some point in their life. About 0.4% of young women are affected in a given year and it is estimated to occur ten times more commonly among women than men. Rates in most of the developing world are unclear. Often it begins during the teen years or young adulthood. While anorexia became more commonly diagnosed during the 20th century it is unclear if this was due to an increase in its frequency or simply better diagnosis. In 2013, it directly resulted in about 600 deaths globally, up from 400 deaths in 1990. Eating disorders also increase a person's risk of death from a wide range of other causes, including
suicide Suicide is the act of intentionally causing one's own death. Mental disorders (including depression, bipolar disorder, schizophrenia, personality disorders, anxiety disorders), physical disorders (such as chronic fatigue syndrome), and s ...
. About 5% of people with anorexia die from complications over a ten-year period, a nearly six times increased risk. According to a study conducted in 2020, it was observed that the unadjusted odds ratio of mortality among male (6.1%) patients was more than twice the ratio for female patients (2.6%) in Japan (Edakubo & Fushimi). The term "anorexia nervosa" was first used in 1873 by
William Gull Sir William Withey Gull, 1st Baronet (31 December 181629 January 1890) was an English physician. Of modest family origins, he established a lucrative private practice and served as Governor of Guy's Hospital, Fullerian Professor of Physiology ...
to describe this condition. In recent years,
evolutionary psychiatry Evolutionary psychiatry, also known as Darwinian psychiatry, is a theoretical approach to psychiatry that aims to explain psychiatric disorders in evolutionary terms. A branch of the field of evolutionary medicine, it is distinct from the medical p ...
as an emerging scientific discipline has been studying
mental disorder A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitti ...
s from an evolutionary perspective. It is still debated whether eating disorders such as anorexia have evolutionary functions or if they are problems resulting from a modern lifestyle.


Signs and symptoms

Anorexia nervosa is an eating disorder characterized by attempts to lose weight to the point of
starvation Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, dea ...
. A person with anorexia nervosa may exhibit a number of signs and symptoms, the type and severity of which may vary and be present but not readily apparent. Anorexia nervosa, and the associated
malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues a ...
that results from self-imposed starvation, can cause complications in every major
organ system An organ system is a biological system consisting of a group of organs that work together to perform one or more functions. Each organ has a specialized role in a plant or animal body, and is made up of distinct tissues. Plants Plants have ...
in the body.
Hypokalaemia Hypokalemia is a low level of potassium (K+) in the blood serum. Mild low potassium does not typically cause symptoms. Symptoms may include feeling tired, leg cramps, weakness, and constipation. Low potassium also increases the risk of an abnor ...
, a drop in the level of potassium in the blood, is a sign of anorexia nervosa. A significant drop in potassium can cause abnormal heart rhythms,
constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...
, fatigue, muscle damage, and
paralysis Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 50 ...
. Signs and symptoms may be classified in physical, cognitive, affective, behavioral and perceptual:


Physical symptoms

* A low
body mass index Body mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m2, resulting from mass in kilograms and he ...
for one's age and height *
Amenorrhea Amenorrhea is the absence of a menstrual period in a woman of reproductive age. Physiological states of amenorrhoea are seen, most commonly, during pregnancy and lactation (breastfeeding). Outside the reproductive years, there is absence of menses ...
, a symptom that occurs after prolonged weight loss, causing menstruation to change drastically or to stop all together * Dry hair and skin, as well as hair thinning * Fear of even the slightest weight gain; taking all precautionary measures to avoid weight gain or becoming "overweight" * Rapid, continuous
weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other conn ...
*
Lanugo Lanugo is very thin, soft, usually unpigmented, downy hair that is sometimes found on the body of a fetus or newborn. It is the first hair to be produced by the fetal hair follicles, and it usually appears around sixteen weeks of gestation and is ...
: soft, fine hair growing over the face and body *
Bradycardia Bradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, a ...
or
tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (su ...
. * Chronic fatigue * Orange discoloration of the skin, particularly the feet (
Carotenosis Carotenosis is a benign and reversible medical condition where an excess of dietary carotenoids results in orange discoloration of the outermost skin layer. The discoloration is most easily observed in light-skinned people and may be mistaken for ...
) * Infertility *
Halitosis Bad breath, also known as halitosis, is a symptom in which a noticeably unpleasant breath odour is present. It can result in anxiety among those affected. It is also associated with depression and symptoms of obsessive compulsive disorder. Th ...
(from vomiting or starvation-induced ketosis) *
Hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dias ...
or
orthostatic hypotension Orthostatic hypotension, also known as postural hypotension, is a medical condition wherein a person's blood pressure drops when standing up or sitting down. Primary orthostatic hypertension is also often referred to as neurogenic orthostatic hyp ...
* Having severe
muscle tension In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sullivan, S. B. (2007). ...
, aches and pains *
Insomnia Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...
*
Abdominal distension Abdominal distension occurs when substances, such as air (gas) or fluid, accumulate in the abdomen causing its expansion. It is typically a symptom of an underlying disease or dysfunction in the body, rather than an illness in its own right. Pe ...


Cognitive symptoms

* An obsession with counting calories and monitoring fat contents of food. * Preoccupation with food, recipes, or cooking; may cook elaborate dinners for others, but not eat the food themselves or consume a very small portion. * Admiration of thinner people. * Thoughts of being fat or not thin enough * An altered mental representation of one's body * Impaired
theory of mind In psychology, theory of mind refers to the capacity to understand other people by ascribing mental states to them (that is, surmising what is happening in their mind). This includes the knowledge that others' mental states may be different fro ...
, exacerbated by lower BMI and depression * Difficulty in abstract thinking and problem solving * Rigid and inflexible thinking * Poor
self-esteem Self-esteem is confidence in one's own worth or abilities. Self-esteem encompasses beliefs about oneself (for example, "I am loved", "I am worthy") as well as emotional states, such as triumph, despair, pride, and shame. Smith and Mackie (2007) d ...
* Hypercriticism and perfectionism


Affective symptoms

* Depression * Ashamed of oneself or one's body *
Anxiety disorders Anxiety disorders are a cluster of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal function are significantly impaired. Anxiety may cause physi ...
* Rapid
mood swings A mood swing is an extreme or sudden change of Mood (psychology), mood. Such changes can play a positive part in promoting problem solving and in producing flexible forward planning, or be disruptive. When mood swings are severe, they may be ...
*
Emotional dysregulation Emotional dysregulation is a range of emotional responses that are poorly modulated and do not lie within a desirable scope of emotive response. Emotional dysregulation can be associated with an experience of early psychological trauma, brain in ...
*
Alexithymia Alexithymia is a personality trait characterized by the inability to identify and describe emotions experienced by oneself. The core characteristic of alexithymia is marked dysfunction in emotional awareness, social attachment, and interpersonal ...


Behavioral symptoms

* Food / energy restrictions despite being
underweight An underweight person is a person whose body weight is considered too low to be healthy. A person who is underweight is malnourished. Assessment The body mass index, a ratio of a person's weight to their height, has traditionally been used t ...
or at a healthy weight. * Food rituals, such as cutting food into tiny pieces, refusing to eat around others, and hiding or discarding of food. * Purging (only in the anorexia purging subtype) with
laxatives Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lub ...
,
diet pills Anti-obesity medication or weight loss medications are pharmacological agents that reduce or control weight. These medications alter one of the fundamental processes of the human body, weight regulation, by altering either appetite, or absor ...
,
ipecac syrup Syrup of ipecac (), or simply ipecac, is a drug that was once widely used as an expectorant (in low doses) and a rapid-acting emetic (in higher doses). It is obtained from the dried rhizome and roots of the ipecacuanha plant (''Carapichea ipecac ...
or
diuretics A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics in ...
to flush food out of their system after eating or engage in self-induced vomiting. Anorexia purging is a subtype of anorexia, where in the person severely restricts most of the time but has reoccurring episodes of binge eating. After bingeing they engage in purging behaviors. This is different from bulimia nervosa. * Excessive exercise, including micro-exercising, for example making small persistent movements of fingers or toes. *
Self harming Self-harm is intentional behavior that is considered harmful to oneself. This is most commonly regarded as direct injury of one's own skin tissues usually without a suicidal intention. Other terms such as cutting, self-injury and self-mutilatio ...
or self-loathing. *
Solitude Solitude is a state of seclusion or isolation, meaning lack of socialisation. Effects can be either positive or negative, depending on the situation. Short-term solitude is often valued as a time when one may work, think, or rest without distu ...
: may avoid friends and family and become more withdrawn and secretive.


Perceptual symptoms

*
Perception Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...
of self as overweight, in contradiction to an underweight reality (namely "
body image disturbance Body image disturbance (BID) is a common symptom in patients with eating disorders and is characterized by an altered perception of one's own body. The onset is mainly attributed to patients with anorexia nervosa who persistently tend to sub ...
") * Intolerance to cold and frequent complaints of being cold; body temperature may lower (
hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe h ...
) in an effort to conserve energy due to malnutrition. * Altered body schema (i.e. an implicit representation of the body evoked by acting) * Altered interoception


Interoception

Interoception involves the conscious and unconscious sense of the internal state of the body, and it has an important role in
homeostasis In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...
and regulation of emotions. Aside from noticeable physiological dysfunction, interoceptive deficits also prompt individuals with anorexia to concentrate on distorted perceptions of multiple elements of their
body image Body image is a person's thoughts, feelings and perception of the aesthetics or sexual attractiveness of their own body. The concept of body image is used in a number of disciplines, including neuroscience, psychology, medicine, psychiatry, ps ...
. This exists in both people with anorexia and in healthy individuals due to impairment in interoceptive sensitivity and interoceptive awareness. Aside from weight gain and outer appearance, people with anorexia also report abnormal bodily functions such as indistinct feelings of fullness. This provides an example of miscommunication between internal signals of the body and the brain. Due to impaired interoceptive sensitivity, powerful cues of fullness may be detected prematurely in highly sensitive individuals, which can result in decreased calorie consumption and generate anxiety surrounding food intake in anorexia patients. People with anorexia also report difficulty identifying and describing their emotional feelings and the inability to distinguish emotions from bodily sensations in general, called
alexithymia Alexithymia is a personality trait characterized by the inability to identify and describe emotions experienced by oneself. The core characteristic of alexithymia is marked dysfunction in emotional awareness, social attachment, and interpersonal ...
. Interoceptive awareness and emotion are deeply intertwined, and could mutually impact each other in abnormalities. Anorexia patients also exhibit emotional regulation difficulties that ignite emotionally-cued eating behaviors, such as restricting food or excessive exercising. Impaired interoceptive sensitivity and interoceptive awareness can lead anorexia patients to adapt distorted interpretations of weight gain that are cued by physical sensations related to digestion (e.g., fullness). Combined, these interoceptive and emotional elements could together trigger maladaptive and negatively reinforced behavioral responses that assist in the maintenance of anorexia. In addition to metacognition, people with anorexia also have difficulty with social cognition including interpreting others' emotions, and demonstrating empathy. Abnormal interoceptive awareness and interoceptive sensitivity shown through all of these examples have been observed so frequently in anorexia that they have become key characteristics of the illness.


Comorbidity

Other psychological issues may factor into anorexia nervosa. Some people have a previous disorder which may increase their vulnerability to developing an eating disorder and some develop them afterwards. The presence of psychiatric comorbidity has been shown to affect the severity and type of anorexia nervosa symptoms in both adolescents and adults. Obsessive-compulsive disorder (OCD) and obsessive-compulsive personality disorder (OCPD) are highly comorbid with AN. OCD is linked with more severe symptomatology and worse prognosis. The
causality Causality (also referred to as causation, or cause and effect) is influence by which one event, process, state, or object (''a'' ''cause'') contributes to the production of another event, process, state, or object (an ''effect'') where the cau ...
between personality disorders and eating disorders has yet to be fully established. Other comorbid conditions include depression,
alcoholism Alcoholism is, broadly, any drinking of alcohol (drug), alcohol that results in significant Mental health, mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognize ...
, borderline and other
personality disorder Personality disorders (PD) are a class of mental disorders characterized by enduring maladaptive patterns of behavior, cognition, and inner experience, exhibited across many contexts and deviating from those accepted by the individual's culture ...
s,
anxiety disorders Anxiety disorders are a cluster of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal function are significantly impaired. Anxiety may cause physi ...
,
attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...
, and
body dysmorphic disorder Body dysmorphic disorder (BDD), occasionally still called dysmorphophobia, is a mental disorder characterized by the obsessive idea that some aspect of one's own body part or appearance is severely flawed and therefore warrants exceptional meas ...
(BDD). Depression and anxiety are the most common comorbidities, and depression is associated with a worse outcome.
Autism spectrum The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
disorders occur more commonly among people with eating disorders than in the general population. Zucker ''et al.'' (2007) proposed that conditions on the autism spectrum make up the cognitive endophenotype underlying anorexia nervosa and appealed for increased interdisciplinary collaboration.


Causes

There is evidence for biological, psychological, developmental, and sociocultural risk factors, but the exact cause of eating disorders is unknown.


Genetic

Anorexia nervosa is highly
heritable Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic informa ...
. Twin studies have shown a heritability rate of 28–58%. First-degree relatives of those with anorexia have roughly 12 times the risk of developing anorexia.
Association studies Genetic association is when one or more genotypes within a population co-occur with a phenotypic trait more often than would be expected by chance occurrence. Studies of genetic association aim to test whether single-locus alleles or genotype fr ...
have been performed, studying 128 different polymorphisms related to 43
genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
including genes involved in regulation of eating behavior,
motivation Motivation is the reason for which humans and other animals initiate, continue, or terminate a behavior at a given time. Motivational states are commonly understood as forces acting within the agent that create a disposition to engage in goal-dire ...
and reward mechanics,
personality traits In psychology, trait theory (also called dispositional theory) is an approach to the study of human personality. Trait theorists are primarily interested in the measurement of ''traits'', which can be defined as habitual patterns of behaviour, tho ...
and
emotion Emotions are mental states brought on by neurophysiological changes, variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or displeasure. There is currently no scientific consensus on a definition. ...
. Consistent associations have been identified for polymorphisms associated with
agouti-related peptide Agouti-related protein (AgRP), also called agouti-related peptide, is a neuropeptide produced in the brain by the AgRP/NPY neuron. It is synthesized in neuropeptide Y (NPY)-containing cell bodies located in the ventromedial part of the arcuate nu ...
,
brain derived neurotrophic factor Brain-derived neurotrophic factor (BDNF), or abrineurin, is a protein found in the and the periphery. that, in humans, is encoded by the ''BDNF'' gene. BDNF is a member of the neurotrophin family of growth factors, which are related to the canon ...
,
catechol-o-methyl transferase Catechol-''O''-methyltransferase (COMT; ) is one of several enzymes that degrade catecholamines (neurotransmitters such as dopamine, epinephrine, and norepinephrine), catecholestrogens, and various drugs and substances having a catechol structu ...
, SK3 and opioid receptor delta-1.
Epigenetic modifications Embryonic stem cells are capable of self-renewing and differentiating to the desired fate depending on their position in the body. Stem cell homeostasis is maintained through epigenetic mechanisms that are highly dynamic in regulating the chromati ...
, such as
DNA methylation DNA methylation is a biological process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts t ...
, may contribute to the development or maintenance of anorexia nervosa, though clinical research in this area is in its infancy. A 2019 study found a genetic relationship with mental disorders, such as
schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...
,
obsessive–compulsive disorder Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which an individual has intrusive thoughts and/or feels the need to perform certain routines repeatedly to the extent where it induces distress or impairs general ...
,
anxiety disorder Anxiety disorders are a cluster of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal function are significantly impaired. Anxiety may cause physi ...
and depression; and metabolic functioning with a negative correlation with fat mass,
type 2 diabetes Type 2 diabetes, formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urinatio ...
and
leptin Leptin (from Ancient Greek, Greek λεπτός ''leptos'', "thin" or "light" or "small") is a hormone predominantly made by adipose cells and enterocytes in the small intestine that helps to regulate Energy homeostasis, energy balance by inhib ...
. One gene that has been linked to anorexia might be of particular interest. This gene codes for a protein called the estrogen related receptor alpha (ERRalpha). In some tissues, this gene alters the ability of estrogen and estrogen receptors to interact with DNA and change the function of cells. Since estrogen has potent effects upon appetite and feeding, any genetic abnormality in the estrogen signaling pathway could contribute to the symptoms of anorexia and explain why anorexia typically appears in young women just after the onset of puberty.


Environmental

Obstetric Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a surg ...
complications: prenatal and perinatal complications may factor into the development of anorexia nervosa, such as
preterm birth Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks Gestational age (obstetrics), gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 we ...
, maternal
anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...
,
diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
,
preeclampsia Pre-eclampsia is a disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy. In severe cases of the disease ...
,
placental infarction A placental infarction results from the interruption of blood supply to a part of the placenta, causing its cells to die. Small placental infarcts, especially at the edge of the placental disc, are considered to be normal at term. Large placent ...
, and neonatal heart abnormalities. Neonatal complications may also have an influence on
harm avoidance Harm avoidance (HA) is a personality trait characterized by excessive worrying; pessimism; shyness; and being fearful, doubtful, and easily fatigued. In MRI studies HA was correlated with reduced grey matter volume in the orbito-frontal, occipita ...
, one of the
personality traits In psychology, trait theory (also called dispositional theory) is an approach to the study of human personality. Trait theorists are primarily interested in the measurement of ''traits'', which can be defined as habitual patterns of behaviour, tho ...
associated with the development of AN. Neuroendocrine dysregulation: altered signalling of peptides that facilitate communication between the gut, brain and
adipose tissue Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...
, such as
ghrelin Ghrelin (; or lenomorelin, INN) is a hormone produced by enteroendocrine cells of the gastrointestinal tract, especially the stomach, and is often called a "hunger hormone" because it increases the drive to eat. Blood levels of ghrelin are highe ...
,
leptin Leptin (from Ancient Greek, Greek λεπτός ''leptos'', "thin" or "light" or "small") is a hormone predominantly made by adipose cells and enterocytes in the small intestine that helps to regulate Energy homeostasis, energy balance by inhib ...
,
neuropeptide Y Neuropeptide Y (NPY) is a 36 amino-acid neuropeptide that is involved in various physiological and homeostatic processes in both the central and peripheral nervous systems. NPY has been identified as the most abundant peptide present in the ma ...
and
orexin Orexin (), also known as hypocretin, is a neuropeptide that regulates arousal, wakefulness, and appetite. The most common form of narcolepsy, type 1, in which the individual experiences brief losses of muscle tone ("drop attacks" or cataplexy) ...
, may contribute to the pathogenesis of anorexia nervosa by disrupting regulation of hunger and satiety.
Gastrointestinal disease Gastrointestinal diseases (abbrev. GI diseases or GI illnesses) refer to diseases involving the gastrointestinal tract, namely the oesophagus, stomach, small intestine, large intestine and rectum, and the accessory organs of digestion, the liver ...
s: people with gastrointestinal disorders may be more at risk of developing disorders of eating practices than the general population, principally restrictive eating disturbances. An association of anorexia nervosa with
celiac disease Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barl ...
has been found. The role that gastrointestinal symptoms play in the development of eating disorders seems rather complex. Some authors report that unresolved symptoms prior to gastrointestinal disease diagnosis may create a food aversion in these persons, causing alterations to their eating patterns. Other authors report that greater symptoms throughout their diagnosis led to greater risk. It has been documented that some people with celiac disease,
irritable bowel syndrome Irritable bowel syndrome (IBS) is a "disorder of gut-brain interaction" characterized by a group of symptoms that commonly include abdominal pain and or abdominal bloating and changes in the consistency of bowel movements. These symptoms may ...
or
inflammatory bowel disease Inflammatory bowel disease (IBD) is a group of inflammation, inflammatory conditions of the colon (anatomy), colon and small intestine, Crohn's disease and ulcerative colitis being the principal types. Crohn's disease affects the small intestine a ...
who are not conscious about the importance of strictly following their diet, choose to consume their trigger foods to promote weight loss. On the other hand, individuals with good dietary management may develop anxiety, food aversion and eating disorders because of concerns around cross contamination of their foods. Some authors suggest that medical professionals should evaluate the presence of an unrecognized celiac disease in all people with eating disorder, especially if they present any gastrointestinal symptom (such as decreased appetite, abdominal pain, bloating, distension, vomiting, diarrhea or constipation), weight loss, or growth failure; and also routinely ask celiac patients about weight or body shape concerns, dieting or vomiting for weight control, to evaluate the possible presence of eating disorders, especially in women. Studies have hypothesized the continuance of disordered eating patterns may be
epiphenomena An epiphenomenon (plural: epiphenomena) is a secondary phenomenon that occurs alongside or in parallel to a primary phenomenon. The word has two senses: one that connotes known causation and one that connotes absence of causation or reservation ...
of starvation. The results of the
Minnesota Starvation Experiment The Minnesota Starvation Experiment, also known as the Minnesota Semi-Starvation Experiment, the Minnesota Starvation-Recovery Experiment and the Starvation Study, was a clinical study performed at the University of Minnesota between November 19, 1 ...
showed normal controls exhibit many of the behavioral patterns of AN when subjected to starvation. This may be due to the numerous changes in the
neuroendocrine system Neuroendocrinology is the branch of biology (specifically of physiology) which studies the interaction between the nervous system and the endocrine system; i.e. how the brain regulates the hormonal activity in the body. The nervous and endocrine ...
, which results in a self-perpetuating cycle. Anorexia nervosa is more likely to occur in a person's pubertal years. Some explanatory hypotheses for the rising prevalence of eating disorders in adolescence are "increase of adipose tissue in girls, hormonal changes of puberty, societal expectations of increased independence and autonomy that are particularly difficult for anorexic adolescents to meet; ndincreased influence of the peer group and its values."


Psychological

Early theories of the cause of anorexia linked it to
childhood sexual abuse Child sexual abuse (CSA), also called child molestation, is a form of child abuse in which an adult or older adolescent uses a child for sexual stimulation. Forms of child sexual abuse include engaging in sexual activities with a child (whether ...
or
dysfunctional families A dysfunctional family is a family in which conflict, misbehavior, and often child neglect or abuse and sometimes even all of the above on the part of individual parents occur continuously and regularly, leading other members to accommodate such ...
; evidence is conflicting, and well-designed research is needed. The fear of food is known as ''sitiophobia'' or ''cibophobia'', and is part of the differential diagnosis. Other psychological causes of anorexia include low self-esteem, feeling like there is lack of control, depression,
anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
, and loneliness. People with anorexia are, in general, highly perfectionistic and most have
obsessive compulsive Obsession may refer to: Psychology * Celebrity worship syndrome, obsessive addictive disorder to a celebrity's personal and professional life * Fixation (psychology), a persistent attachment to an object or idea * Idée fixe (psychology), a preo ...
personality traits which may facilitate sticking to a restricted diet. It has been suggested that patients with anorexia are rigid in their thought patterns, and place a high level of importance upon being thin. A risk factor for anorexia is
trauma Trauma most often refers to: * Major trauma, in physical medicine, severe physical injury caused by an external source * Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic i ...
. Although the prevalence rates vary greatly, between 37% and 100%, there appears to be a link between traumatic events and eating disorder diagnosis. Approximately 72% of individuals with anorexia report experiencing a traumatic event prior to the onset of eating disorder symptoms, with binge-purge subtype reporting the highest rates. There are many traumatic events that may be risk factors for development of anorexia, the first identified traumatic event predicting anorexia was childhood sexual abuse. However, other traumatic events, such as physical and emotional abuse have also been found to be risk factors. Interpersonal, as opposed to non-interpersonal trauma, has been seen as the most common type of traumatic event, which can encompass sexual, physical, and emotional abuse. Individuals who experience repeated trauma, like those who experience trauma perpetrated by a caregiver or loved one, have increased symptom severity of anorexia and a greater prevalence of comorbid psychiatric diagnoses. In individuals with anorexia, the prevalence rates for those who also qualify for a
PTSD Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats on a ...
diagnosis ranges from 4% to 52% in non-clinical samples to 10% to 47% in clinical samples. A complicated symptom profile develops when trauma and anorexia meld; the bodily experience of the individual is changed and intrusive thoughts and sensations may be experienced. Traumatic events can lead to intrusive and obsessive thoughts, and the symptom of anorexia that has been most closely linked to a PTSD diagnosis is increased obsessive thoughts pertaining to food. Similarly, impulsivity is linked to the purge and binge-purge subtypes of anorexia, trauma, and PTSD. Emotional trauma (e.g., invalidation, chaotic family environment in childhood) may lead to difficulty with emotions, particularly the identification of and how physical sensations contribute to the emotional response. Trauma and traumatic events can disturb an individual's sense of self and affect their ability to thrive, especially within their bodies. When trauma is perpetrated on an individual, it can lead to feelings of not being safe within their own body; that their body is for others to use and not theirs alone. Individuals may experience a feeling of disconnection from their body after a traumatic experience, leading to a desire to distance themselves from the body. Trauma overwhelms individuals emotionally, physically, and psychologically. Both physical and sexual abuse can lead to an individual seeing their body as belonging to an "other" and not to the "self". Individuals who feel as though they have no control over their bodies due to trauma may use food as a means of control because the choice to eat is an unmatched expression of control. By exerting control over food, individuals can choose when to eat and how much to eat. Individuals, particularly children experiencing abuse, may feel a loss of control over their life, circumstances, and their own bodies. Particularly
sexual abuse Sexual abuse or sex abuse, also referred to as molestation, is abusive sexual behavior by one person upon another. It is often perpetrated using force or by taking advantage of another. Molestation often refers to an instance of sexual assa ...
, but also
physical abuse Physical abuse is any intentional act causing injury or trauma to another person or animal by way of bodily contact. In most cases, children are the victims of physical abuse, but adults can also be victims, as in cases of domestic violence or wo ...
, can make individuals feel that the body is not a safe place and an object over which another has control.
Starvation Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, dea ...
, in the case of anorexia, may also lead to reduction in the body as a sexual object, making starvation a solution. Restriction may also be a means by which the pain an individual is experiencing can be communicated.


Sociological

Anorexia nervosa has been increasingly diagnosed since 1950; the increase has been linked to vulnerability and internalization of body ideals. People in professions where there is a particular social pressure to be thin (such as models and dancers) were more likely to develop anorexia, and those with anorexia have much higher contact with cultural sources that promote weight loss. This trend can also be observed for people who partake in certain sports, such as jockeys and wrestlers. There is a higher incidence and prevalence of anorexia nervosa in sports with an emphasis on aesthetics, where low body fat is advantageous, and sports in which one has to make weight for competition. Family
group dynamics Group dynamics is a system of behaviors and psychological processes occurring within a social group (''intra''group dynamics), or between social groups ( ''inter''group dynamics). The study of group dynamics can be useful in understanding decision- ...
can play a role in the cause of anorexia including negative expressed emotion in overprotective families where blame is frequently experienced among its members. When there is a constant pressure from people to be thin, teasing and bullying can cause low self-esteem and other psychological symptoms.


Media effects

Persistent exposure to media that present body ideals may constitute a risk factor for body dissatisfaction and anorexia nervosa. The cultural ideal for body shape for men versus women continues to favor slender women and athletic, V-shaped muscular men. A 2002 review found that, of the magazines most popular among people aged 18 to 24 years, those read by men, unlike those read by women, were more likely to feature ads and articles on shape than on diet. Body dissatisfaction and internalization of body ideals are risk factors for anorexia nervosa that threaten the health of both male and female populations. Another online aspect contributing to higher rates of eating disorders such as anorexia nervosa are websites and communities on social media that stress the importance of attainment of body ideals extol and promote anorexia nervosa through the use of religious metaphors, lifestyle descriptions, "thinspiration" or "fitspiration" (inspirational photo galleries and quotes that aim to serve as motivators for attainment of body ideals). Pro-anorexia websites reinforce internalization of body ideals and the importance of their attainment. The media portray a false view of what people truly look like. In magazines and movies and even on billboards most of the actors/models are digitally altered in multiple ways. People then strive to look like these "perfect" role models when in reality they are not near perfection themselves.


Mechanisms

Evidence from physiological, pharmacological and neuroimaging studies suggest
serotonin Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vas ...
(also called 5-HT) may play a role in anorexia. While acutely ill, metabolic changes may produce a number of biological findings in people with anorexia that are not necessarily causative of the anorexic behavior. For example, abnormal hormonal responses to challenges with serotonergic agents have been observed during acute illness, but not recovery. Nevertheless, increased
cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...
concentrations of 5-hydroxyindoleacetic acid (a metabolite of serotonin), and changes in anorectic behavior in response to
acute tryptophan depletion Acute tryptophan depletion (ATD) is a technique used extensively to study the effect of low serotonin in the brain. This experimental approach reduces the availability of tryptophan, an amino acid Amino acids are organic compounds that contai ...
(
tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...
is a metabolic precursor to serotonin) support a role in anorexia. The activity of the 5-HT2A receptors has been reported to be lower in patients with anorexia in a number of cortical regions, evidenced by lower
binding potential In pharmacokinetics and receptor-ligand kinetics the binding potential (BP) is a combined measure of the density of "available" neuroreceptors and the affinity of a drug to that neuroreceptor. Description Consider a ligand receptor binding syst ...
of this receptor as measured by
PET A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive appearances, intelligence, ...
or
SPECT Single-photon emission computed tomography (SPECT, or less commonly, SPET) is a nuclear medicine tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera (that is, ...
, independent of the state of illness. While these findings may be confounded by comorbid psychiatric disorders, taken as a whole they indicate serotonin in anorexia. These alterations in serotonin have been linked to traits characteristic of anorexia such as obsessiveness, anxiety, and appetite dysregulation. Neuroimaging studies investigating the functional connectivity between brain regions have observed a number of alterations in networks related to cognitive control, introspection, and sensory function. Alterations in networks related to the dorsal anterior cingulate cortex may be related to excessive cognitive control of eating related behaviors. Similarly, altered somatosensory integration and introspection may relate to abnormal body image. A review of functional neuroimaging studies reported reduced activations in "bottom up" limbic region and increased activations in "top down" cortical regions which may play a role in restrictive eating. Compared to controls, people who have recovered from anorexia show reduced activation in the
reward system The reward system (the mesocorticolimbic circuit) is a group of neural structures responsible for incentive salience (i.e., "wanting"; desire or craving for a reward and motivation), associative learning (primarily positive reinforcement and class ...
in response to food, and reduced correlation between self reported liking of a sugary drink and activity in the
striatum The striatum, or corpus striatum (also called the striate nucleus), is a nucleus (a cluster of neurons) in the subcortical basal ganglia of the forebrain. The striatum is a critical component of the motor and reward systems; receives glutamate ...
and
anterior cingulate cortex In the human brain, the anterior cingulate cortex (ACC) is the frontal part of the cingulate cortex that resembles a "collar" surrounding the frontal part of the corpus callosum. It consists of Brodmann areas 24, 32, and 33. It is involved ...
. Increased binding potential of 11C radiolabelled
raclopride Raclopride is a typical antipsychotic. It acts as a selective antagonist on D2 dopamine receptors. It has been used in trials studying Parkinson Disease. Its selectivity to the cerebral D2 receptors is characterized by its respective Ki-valu ...
in the striatum, interpreted as reflecting decreased endogenous
dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...
due to competitive displacement, has also been observed. Structural neuroimaging studies have found global reductions in both gray matter and white matter, as well as increased cerebrospinal fluid volumes. Regional decreases in the left
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...
, left inferior
parietal lobe The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory informa ...
, right
lentiform nucleus The lentiform nucleus, or lenticular nucleus, comprises the putamen and the globus pallidus within the basal ganglia. With the caudate nucleus, it forms the dorsal striatum. It is a large, lens-shaped mass of gray matter just lateral to the inter ...
and right caudate have also been reported in acutely ill patients. However, these alterations seem to be associated with acute malnutrition and largely reversible with weight restoration, at least in nonchronic cases in younger people. In contrast, some studies have reported increased
orbitofrontal cortex The orbitofrontal cortex (OFC) is a prefrontal cortex region in the frontal lobes of the brain which is involved in the cognitive process of decision-making. In non-human primates it consists of the association cortex areas Brodmann area 11, 12 ...
volume in currently ill and  in recovered patients, although findings are inconsistent. Reduced
white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribution ...
integrity in the fornix has also been reported.


Diagnosis

A diagnostic assessment includes the person's current circumstances, biographical history, current symptoms, and family history. The assessment also includes a
mental state examination The mental status examination (MSE) is an important part of the clinical assessment process in neurological and psychiatric practice. It is a structured way of observing and describing a patient's psychological functioning at a given point in ti ...
, which is an assessment of the person's current mood and thought content, focusing on views on weight and patterns of eating.


DSM-5

Anorexia nervosa is classified under the Feeding and Eating Disorders in the latest revision of the ''
Diagnostic and Statistical Manual of Mental Disorders The ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM; latest edition: DSM-5-TR, published in March 2022) is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common langua ...
'' (DSM 5). There is no specific BMI cut-off that defines low weight required for the diagnosis of anorexia nervosa. The diagnostic criteria for anorexia nervosa (all of which needing to be met for diagnosis) are: *Restriction of energy intake relative to requirements leading to a low body weight. (Criterion A) *Intense fear of gaining weight or persistent behaviors that interfere with gaining weight. (Criterion B) * Disturbance in the way a person's weight or body shape is experienced or a lack of recognition about the risks of the low body weight. (Criterion C) Relative to the previous version of the DSM (
DSM-IV-TR The ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM; latest edition: DSM-5-TR, published in March 2022) is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common langua ...
), the 2013 revision (DSM5) reflects changes in the criteria for anorexia nervosa. Most notably, the
amenorrhea Amenorrhea is the absence of a menstrual period in a woman of reproductive age. Physiological states of amenorrhoea are seen, most commonly, during pregnancy and lactation (breastfeeding). Outside the reproductive years, there is absence of menses ...
(absent
period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...
) criterion was removed. Amenorrhea was removed for several reasons: it does not apply to males, it is not applicable for females before or after the age of menstruation or taking birth control pills, and some women who meet the other criteria for AN still report some menstrual activity.


Subtypes

There are two subtypes of AN: * Binge-eating/purging type: patients with anorexia could show binge eating and purging behavior. It is different from
bulimia nervosa Bulimia nervosa, also known as simply bulimia, is an eating disorder characterized by binge eating followed by purging or fasting, and excessive concern with body shape and weight. The aim of this activity is to expel the body of calories eate ...
in terms of the individual's weight. An individual with binge-eating/purging type anorexia is usually significantly underweight. People with
bulimia nervosa Bulimia nervosa, also known as simply bulimia, is an eating disorder characterized by binge eating followed by purging or fasting, and excessive concern with body shape and weight. The aim of this activity is to expel the body of calories eate ...
on the other hand can sometimes be normal-weight or overweight. * Restricting type: the individual uses restricting food intake, fasting, diet pills, or exercise as a means for losing weight; they may exercise excessively to keep off weight or prevent weight gain, and some individuals eat only enough to stay alive. In the restrictive type, there are no recurrent episodes of binge-eating or purging present.


Levels of severity

Body mass index Body mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m2, resulting from mass in kilograms and he ...
(BMI) is used by the DSM-5 as an indicator of the level of severity of anorexia nervosa. The DSM-5 states these as follows: * Mild: BMI of greater than 17 * Moderate: BMI of 16–16.99 * Severe: BMI of 15–15.99 * Extreme: BMI of less than 15


Investigations

Medical tests to check for signs of physical deterioration in anorexia nervosa may be performed by a general physician or psychiatrist, including: *
Complete blood count A complete blood count (CBC), also known as a full blood count (FBC), is a set of medical laboratory tests that provide cytometry, information about the cells in a person's blood. The CBC indicates the counts of white blood cells, red blood cell ...
(CBC): a test of the
white blood cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...
,
red blood cells Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek language, Greek ''erythros'' for "red" and ''k ...
and
platelets Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby ini ...
used to assess the presence of various disorders such as
leukocytosis Leukocytosis is a condition in which the white cell (leukocyte count) is above the normal range in the blood. It is frequently a sign of an inflammatory response, most commonly the result of infection, but may also occur following certain parasi ...
,
leukopenia Leukopenia () is a decrease in the number of leukocytes (WBC). Found in the blood, they are the white blood cells, and are the body's primary defense against an infection. Thus the condition of leukopenia places individuals at increased risk of inf ...
,
thrombocytosis Thrombocythemia is a condition of high platelet (thrombocyte) count in the blood. Normal count is in the range of 150x109 to 450x109 platelets per liter of blood, but investigation is typically only considered if the upper limit exceeds 750x109/L. ...
and
anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...
which may result from
malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues a ...
. *
Urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic e ...
: a variety of tests performed on the urine used in the diagnosis of medical disorders, to test for substance abuse, and as an indicator of overall health * Chem-20: Chem-20 also known as SMA-20 a group of twenty separate chemical tests performed on
blood serum Serum () is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum includes all proteins not u ...
. Tests include
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
and
electrolytes An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon di ...
such as
potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
,
chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
and
sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
and tests specific to
liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
and
kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
function. *
Glucose tolerance test The glucose tolerance test (GTT, not to be confused with GGT test) is a medical test in which glucose is given and blood samples taken afterward to determine how quickly it is cleared from the blood. The test is usually used to test for diabetes, ...
: Oral glucose tolerance test (OGTT) used to assess the body's ability to metabolize glucose. Can be useful in detecting various disorders such as
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, an
insulinoma An insulinoma is a tumour of the pancreas that is derived from beta cells and secretes insulin. It is a rare form of a neuroendocrine tumour. Most insulinomas are benign in that they grow exclusively at their origin within the pancreas, but a min ...
,
Cushing's Syndrome Cushing's syndrome is a collection of signs and symptoms due to prolonged exposure to glucocorticoids such as cortisol. Signs and symptoms may include high blood pressure, abdominal obesity but with thin arms and legs, reddish stretch marks, a ...
,
hypoglycemia Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose belo ...
and
polycystic ovary syndrome Polycystic ovary syndrome, or PCOS, is the most common endocrine disorder in women of reproductive age. The syndrome is named after the characteristic cysts which may form on the ovaries, though it is important to note that this is a sign and no ...
. *
Lipid profile A lipid profile or lipid panel is a panel of blood tests used to find abnormalities in lipids, such as cholesterol and triglycerides. The results of this test can identify certain genetic diseases and can determine approximate risks for cardiovas ...
: includes
cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
(including
total cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell membrane ...
, HDL and
LDL Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall densit ...
) and
triglycerides A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and ''glyceride''). Triglycerides are the main constituents of body fat in humans and other vertebrates, as we ...
. * Serum
cholinesterase The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters: : an acylcholine + H2O = choline + a carboxylate Several of these serve as neurotransmitters ...
test: a test of liver enzymes (
acetylcholinesterase Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme Enzymes () are proteins that a ...
and pseudocholinesterase) useful as a test of liver function and to assess the effects of malnutrition. *
Liver Function Test Liver function tests (LFTs or LFs), also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient's liver. These tests include prothrombin time (PT/INR), activated partial thromboplastin ti ...
: A series of tests used to assess liver function some of the tests are also used in the assessment of malnutrition,
protein deficiency Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...
, kidney function, bleeding disorders, and Crohn's Disease. *
Luteinizing hormone Luteinizing hormone (LH, also known as luteinising hormone, lutropin and sometimes lutrophin) is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) ...
(LH) response to
gonadotropin-releasing hormone Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and released ...
(GnRH): Tests the pituitary glands' response to GnRh, a hormone produced in the hypothalamus.
Hypogonadism Hypogonadism means diminished functional activity of the gonads—the testes or the ovaries—that may result in diminished production of sex hormones. Low androgen (e.g., testosterone) levels are referred to as hypoandrogenism and low estrogen ...
is often seen in anorexia nervosa cases. *
Creatine kinase Creatine kinase (CK), also known as creatine phosphokinase (CPK) or phosphocreatine kinase, is an enzyme () expressed by various tissues and cell types. CK catalyses the conversion of creatine and uses adenosine triphosphate (ATP) to create phosp ...
(CK) test: measures the circulating blood levels of creatine kinase an enzyme found in the heart (
CK-MB The CPK-MB test (creatine phosphokinase-MB), also known as CK-MB test, is a cardiac marker used to assist diagnoses of an acute myocardial infarction, myocardial ischemia, or myocarditis. It measures the blood level of CK-MB (creatine kinase myoca ...
), brain (CK-BB) and skeletal muscle (CK-MM). * Blood urea nitrogen (BUN) test: urea nitrogen is the byproduct of protein metabolism first formed in the liver then removed from the body by the kidneys. The BUN test is primarily used to test
kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
function. A low BUN level may indicate the effects of malnutrition. *
BUN-to-creatinine ratio In medicine, the BUN-to-creatinine ratio is the ratio of two serum laboratory values, the blood urea nitrogen (BUN) (mg/dL) and serum creatinine (Cr) (mg/dL). Outside the United States, particularly in Canada and Europe, the term urea is often us ...
: A BUN to creatinine ratio is used to predict various conditions. A high BUN/creatinine ratio can occur in severe hydration, acute kidney failure, congestive heart failure, and intestinal bleeding. A low BUN/creatinine ratio can indicate a low protein diet,
celiac disease Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barl ...
,
rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of th ...
, or
cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue repai ...
of the liver. * Electrocardiogram (EKG or ECG): measures electrical activity of the heart. It can be used to detect various disorders such as
hyperkalemia Hyperkalemia is an elevated level of potassium (K+) in the blood. Normal potassium levels are between 3.5 and 5.0mmol/L (3.5 and 5.0mEq/L) with levels above 5.5mmol/L defined as hyperkalemia. Typically hyperkalemia does not cause symptoms. Occasi ...
. *
Electroencephalogram Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...
(EEG): measures the electrical activity of the brain. It can be used to detect abnormalities such as those associated with pituitary tumors. *
Thyroid function tests The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
: tests used to assess thyroid functioning by checking levels of thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3).


Differential diagnoses

A variety of medical and psychological conditions have been misdiagnosed as anorexia nervosa; in some cases the correct diagnosis was not made for more than ten years. The distinction between binge purging anorexia,
bulimia nervosa Bulimia nervosa, also known as simply bulimia, is an eating disorder characterized by binge eating followed by purging or fasting, and excessive concern with body shape and weight. The aim of this activity is to expel the body of calories eate ...
and Other Specified Feeding or Eating Disorders (OSFED) is often difficult for non-specialist clinicians. A main factor differentiating binge-purge anorexia from bulimia is the gap in physical weight. Patients with bulimia nervosa are ordinarily at a healthy weight, or slightly overweight. Patients with binge-purge anorexia are commonly underweight. Moreover, patients with the binge-purging subtype may be significantly underweight and typically do not binge-eat large amounts of food. In contrast, those with bulimia nervosa tend to binge large amounts of food. It is not unusual for patients with an eating disorder to "move through" various diagnoses as their behavior and beliefs change over time.


Treatment

There is no conclusive evidence that any particular treatment for anorexia nervosa works better than others. Treatment for anorexia nervosa tries to address three main areas. * Restoring the person to a healthy weight; * Treating the psychological disorders related to the illness; * Reducing or eliminating behaviors or thoughts that originally led to the disordered eating. In some clinical settings a specific body image intervention is performed to reduce body dissatisfaction and
body image disturbance Body image disturbance (BID) is a common symptom in patients with eating disorders and is characterized by an altered perception of one's own body. The onset is mainly attributed to patients with anorexia nervosa who persistently tend to sub ...
. Although restoring the person's weight is the primary task at hand, optimal treatment also includes and monitors behavioral change in the individual as well. There is some evidence that hospitalization might adversely affect long term outcome, but sometimes is necessary.
Psychotherapy Psychotherapy (also psychological therapy, talk therapy, or talking therapy) is the use of psychological methods, particularly when based on regular personal interaction, to help a person change behavior, increase happiness, and overcome pro ...
for individuals with AN is challenging as they may value being thin and may seek to maintain control and resist change. Initially, developing a desire to change is fundamental. Despite no evidence for better treatment in adults patients, research stated that family based therapy is the primary choice for adolescents with AN.


Therapy

Family-based treatment (FBT) has been shown to be more successful than individual therapy for adolescents with AN. Various forms of family-based treatment have been proven to work in the treatment of adolescent AN including conjoint family therapy (CFT), in which the parents and child are seen together by the same therapist, and separated family therapy (SFT) in which the parents and child attend therapy separately with different therapists. Proponents of family therapy for adolescents with AN assert that it is important to include parents in the adolescent's treatment. A four- to five-year follow up study of the Maudsley family therapy, an evidence-based manualized model, showed full recovery at rates up to 90%. The Maudsley model of family therapy is problem focused, and the treatment targets re-establishing regular eating, weight restoration, and the reduction of illness behaviors like purging. The Maudsley model is split into three phases, with phase on focusing on the parents implementing weight restoration in the child; phase two transitioning control over food back to the individual at an age-appropriate level; and phase three focusing on other issues related to typical adolescent development (e.g., social and other psychological developments), and helps parents learn how to interact with their child. Although this model is recommended by the
NIMH NIMH may refer to: *Nickel–metal hydride battery (NiMH), a type of electrical battery *National Institute of Mental Health, an agency of the United States government *National Institute of Medical Herbalists, a professional organisation in the Un ...
, critics claim that it has the potential to create power struggles in an intimate relationship and may disrupt equal partnerships.
Cognitive behavioral therapy Cognitive behavioral therapy (CBT) is a psycho-social intervention that aims to reduce symptoms of various mental health conditions, primarily depression and anxiety disorders. CBT focuses on challenging and changing cognitive distortions (suc ...
(CBT) is useful in adolescents and adults with anorexia nervosa. One of the most known psychotherapy in the field is CBT-E, an enhanced cognitive-behavior therapy specifically focus to eating disorder psychopathology.
Acceptance and commitment therapy Acceptance and commitment therapy (ACT, typically pronounced as the word "act") is a form of psychotherapy, as well as a branch of clinical behavior analysis. It is an empirically based psychological intervention that uses acceptance and mindfu ...
is a third-wave cognitive-behavioral therapy which has shown promise in the treatment of AN.
Cognitive remediation therapy Cognitive remediation is designed to improve neurocognitive abilities such as attention, working memory, cognitive flexibility and planning, and executive functioning which leads to improved psychosocial functioning. Empirical support Empirical s ...
(CRT) is also used in treating anorexia nervosa. Schema-Focused Therapy (a form of CBT) was developed by Dr. Jeffrey Young and is effective in helping patients identify origins and triggers for disordered eating.


Diet

Diet is the most essential factor to work on in people with anorexia nervosa, and must be tailored to each person's needs. Food variety is important when establishing meal plans as well as foods that are higher in energy density. People must consume adequate calories, starting slowly, and increasing at a measured pace. Evidence of a role for
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
supplementation during refeeding is unclear.


Medication

Pharmaceuticals have limited benefit for anorexia itself. There is a lack of good information from which to make recommendations concerning the effectiveness of antidepressants in treating anorexia. Administration of
olanzapine Olanzapine (sold under the trade name Zyprexa among others) is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. For schizophrenia, it can be used for both new-onset disease and long-term maintenance. It is t ...
has been shown to result in a modest but statistically significant increase in body weight of anorexia nervosa patients.


Admission to hospital

Patients with AN may be deemed to have a lack of insight regarding the necessity of treatment, and thus may be involuntarily treated without their consent. AN has a high mortality and patients admitted in a severely ill state to medical units are at particularly high risk. Diagnosis can be challenging, risk assessment may not be performed accurately, consent and the need for compulsion may not be assessed appropriately, refeeding syndrome may be missed or poorly treated and the behavioural and family problems in AN may be missed or poorly managed. Guidelines published by the
Royal College of Psychiatrists The Royal College of Psychiatrists is the main professional organisation of psychiatrists in the United Kingdom, and is responsible for representing psychiatrists, for psychiatric research and for providing public information about mental health ...
recommend that medical and psychiatric experts work together in managing severely ill people with AN.


Refeeding syndrome

The rate of refeeding can be difficult to establish, because the fear of refeeding syndrome (RFS) can lead to underfeeding. It is thought that RFS, with falling phosphate and potassium levels, is more likely to occur when BMI is very low, and when medical comorbidities such as infection or cardiac failure, are present. In those circumstances, it is recommended to start refeeding slowly but to build up rapidly as long as RFS does not occur. Recommendations on energy requirements vary, from 5–10 kcal/kg/day in the most medically compromised patients, who appear to have the highest risk of RFS, to 1900 kcal/day.


Experience of treatment

Patients involved in treatment sometimes felt that treatment focused on biological aspects of body weight and eating behaviour change rather than their perceptions or emotional state. Patients felt that a therapists trust in them shown by being treated as a complete person with their own capacities was significant. Some patients defined
recovery Recovery or Recover may refer to: Arts and entertainment Books * ''Recovery'' (novel), a Star Wars e-book * Recovery Version, a translation of the Bible with footnotes published by Living Stream Ministry Film and television * ''Recovery'' (fil ...
from AN in terms of reclaiming a lost
identity Identity may refer to: * Identity document * Identity (philosophy) * Identity (social science) * Identity (mathematics) Arts and entertainment Film and television * ''Identity'' (1987 film), an Iranian film * ''Identity'' (2003 film), ...
. Healthcare workers involved in the treatment of anorexia reported frustration and anger to set backs in treatment and noncompliance and were afraid of patients dying. Some healthcare workers felt that they did not understand the treatment and that medical doctors were making decisions. They may feel powerless to improve a patient's situation and deskilled as a result. Healthcare workers involved in monitoring patients consumption of food felt watched themselves. Healthcare workers often feel a degree of
moral dissonance In the field of psychology, cognitive dissonance is the perception of contradictory information, and the mental toll of it. Relevant items of information include a person's actions, feelings, ideas, beliefs, values, and things in the environment. ...
of not being in control of outcomes which they may protect against by focusing on individual tasks, avoiding identifying with patients (for example by making their eating behavior very different and not sharing personal information with patients), and blaming patients for their distress. Healthcare workers would inflexibly follow process to avoid responsibility. Healthcare workers attempted to reach balance by gradually giving patients back control avoiding feeling sole responsibility for outcomes, being mindful of their emotional state, and trying to view eating disorders as external from patients.


Prognosis

AN has the highest mortality rate of any psychological disorder. The mortality rate is 11 to 12 times greater than in the general population, and the suicide risk is 56 times higher. Half of women with AN achieve a full recovery, while an additional 20–30% may partially recover. Not all people with anorexia recover completely: about 20% develop anorexia nervosa as a chronic disorder. If anorexia nervosa is not treated, serious complications such as heart conditions and kidney failure can arise and eventually lead to death. The average number of years from onset to remission of AN is seven for women and three for men. After ten to fifteen years, 70% of people no longer meet the diagnostic criteria, but many still continue to have eating-related problems.
Alexithymia Alexithymia is a personality trait characterized by the inability to identify and describe emotions experienced by oneself. The core characteristic of alexithymia is marked dysfunction in emotional awareness, social attachment, and interpersonal ...
(inability to identify and describe one's own emotions) influences treatment outcome. Recovery is also viewed on a spectrum rather than black and white. According to the Morgan-Russell criteria, individuals can have a good, intermediate, or poor outcome. Even when a person is classified as having a "good" outcome, weight only has to be within 15% of average, and normal menstruation must be present in females. The good outcome also excludes psychological health. Recovery for people with anorexia nervosa is undeniably positive, but recovery does not mean a return to normal.


Complications

Anorexia nervosa can have serious implications if its duration and severity are significant and if onset occurs before the completion of growth, pubertal maturation, or the attainment of
peak bone mass Peak bone mass is the maximum amount of bone a person has during their life. It typically occurs in the early 20s in females and late 20s in males. Peak bone mass is typically lower in females than males, and is also lower in White people Whi ...
. Complications specific to adolescents and children with anorexia nervosa can include the following: Growth retardation may occur, as height gain may slow and can stop completely with severe weight loss or chronic malnutrition. In such cases, provided that growth potential is preserved, height increase can resume and reach full potential after normal intake is resumed. Height potential is normally preserved if the duration and severity of illness are not significant or if the illness is accompanied by delayed bone age (especially prior to a bone age of approximately 15 years), as
hypogonadism Hypogonadism means diminished functional activity of the gonads—the testes or the ovaries—that may result in diminished production of sex hormones. Low androgen (e.g., testosterone) levels are referred to as hypoandrogenism and low estrogen ...
may partially counteract the effects of undernutrition on height by allowing for a longer duration of growth compared to controls. Appropriate early treatment can preserve height potential, and may even help to increase it in some post-anorexic subjects, due to factors such as long-term reduced estrogen-producing
adipose tissue Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...
levels compared to premorbid levels. In some cases, especially where onset is before puberty, complications such as stunted growth and pubertal delay are usually reversible. Anorexia nervosa causes alterations in the female reproductive system; significant weight loss, as well as psychological stress and intense exercise, typically results in a cessation of menstruation in women who are past puberty. In patients with anorexia nervosa, there is a reduction of the secretion of
gonadotropin releasing hormone Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and released ...
in the central nervous system, preventing ovulation. Anorexia nervosa can also result in pubertal delay or arrest. Both height gain and pubertal development are dependent on the release of growth hormone and gonadotropins (LH and FSH) from the pituitary gland. Suppression of gonadotropins in people with anorexia nervosa has been documented. Typically,
growth hormone Growth hormone (GH) or somatotropin, also known as human growth hormone (hGH or HGH) in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in h ...
(GH) levels are high, but levels of
IGF-1 Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults. IGF-1 is a protein that in humans is ...
, the downstream hormone that should be released in response to GH are low; this indicates a state of "resistance" to GH due to chronic starvation. IGF-1 is necessary for bone formation, and decreased levels in anorexia nervosa contribute to a loss of
bone density Bone density, or bone mineral density, is the amount of bone mineral in bone tissue. The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optica ...
and potentially contribute to
osteopenia Osteopenia, known as "low bone mass" or "low bone density", is a condition in which bone mineral density is low. Because their bones are weaker, people with osteopenia may have a higher risk of fractures, and some people may go on to develop osteop ...
or
osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...
. Anorexia nervosa can also result in reduction of peak bone mass. Buildup of bone is greatest during adolescence, and if onset of anorexia nervosa occurs during this time and stalls puberty, low bone mass may be permanent. Hepatic steatosis, or fatty infiltration of the liver, can also occur, and is an indicator of malnutrition in children. Neurological disorders that may occur as complications include
seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with los ...
s and
tremor A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, fa ...
s.
Wernicke encephalopathy Wernicke encephalopathy (WE), also Wernicke's encephalopathy, or wet brain is the presence of neurological symptoms caused by biochemical lesions of the central nervous system after exhaustion of B-vitamin reserves, in particular thiamine (vit ...
, which results from
vitamin B1 deficiency Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thi ...
, has been reported in patients who are extremely malnourished; symptoms include confusion, problems with the muscles responsible for eye movements and abnormalities in walking gait. The most common gastrointestinal complications of anorexia nervosa are delayed stomach emptying and
constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...
, but also include elevated
liver function tests Liver function tests (LFTs or LFs), also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient's liver. These tests include prothrombin time (PT/INR), activated partial thromboplastin ti ...
,
diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...
,
acute pancreatitis Acute pancreatitis (AP) is a sudden inflammation of the pancreas. Causes in order of frequency include: 1) a gallstone impacted in the common bile duct beyond the point where the pancreatic duct joins it; 2) heavy alcohol use; 3) systemic disea ...
,
heartburn Heartburn, also known as pyrosis, cardialgia or acid indigestion, is a burning sensation in the central chest or upper central abdomen. Heartburn is usually due to regurgitation of gastric acid (gastric reflux) into the esophagus. It is the m ...
,
difficulty swallowing Dysphagia is difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right. It may be a sensation that suggests difficulty in the passage of solids or liqui ...
, and, rarely,
superior mesenteric artery syndrome Superior mesenteric artery (SMA) syndrome is a gastro-vascular disorder in which the third and final portion of the duodenum is compressed between the abdominal aorta (AA) and the overlying superior mesenteric artery. This rare, potentially life ...
. Delayed stomach emptying, or gastroparesis, often develops following food restriction and weight loss; the most common symptom is bloating with gas and abdominal distension, and often occurs after eating. Other symptoms of gastroparesis include early satiety, fullness, nausea, and vomiting. The symptoms may inhibit efforts at eating and recovery, but can be managed by limiting high-fiber foods, using liquid nutritional supplements, or using
metoclopramide Metoclopramide is a medication used for stomach and esophageal problems. It is commonly used to treat and prevent nausea and vomiting, to help with emptying of the stomach in people with delayed stomach emptying, and to help with gastroesoph ...
to increase emptying of food from the stomach. Gastroparesis generally resolves when weight is regained.


Cardiac complications

Anorexia nervosa increases the risk of
sudden cardiac death Cardiac arrest is when the heart suddenly and unexpectedly stops beating. It is a medical emergency that, without immediate medical intervention, will result in sudden cardiac death within minutes. Cardiopulmonary resuscitation (CPR) and possib ...
, though the precise cause is unknown. Cardiac complications include structural and functional changes to the heart. Some of these cardiovascular changes are mild and are reversible with treatment, while others may be life-threatening. Cardiac complications can include
arrhythmias Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...
, abnormally slow heart beat,
low blood pressure Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...
, decreased size of the heart muscle, reduced heart volume, mitral valve prolapse,
myocardial fibrosis Cardiac fibrosis commonly refers to the excess deposition of extracellular matrix in the cardiac muscle, but the term may also refer to an abnormal thickening of the heart valves due to inappropriate proliferation of cardiac fibroblasts. Fibrotic c ...
, and
pericardial effusion A pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. The pericardium is a two-part membrane surrounding the heart: the outer fibrous connective membrane and an inner two-layered serous membrane. The two layers of t ...
. Abnormalities in conduction and repolarization of the heart that can result from anorexia nervosa include
QT prolongation Long QT syndrome (LQTS) is a condition affecting repolarization (relaxing) of the heart after a heartbeat, giving rise to an abnormally lengthy QT interval. It results in an increased risk of an irregular heartbeat which can result in fainting, ...
, increased QT dispersion, conduction delays, and
junctional escape rhythms A junctional escape beat is a delayed heartbeat originating not from the atrium but from an ectopic focus somewhere in the atrioventricular junction. It occurs when the rate of depolarization of the sinoatrial node falls below the rate of the a ...
. Electrolyte abnormalities, particularly
hypokalemia Hypokalemia is a low level of potassium (K+) in the blood serum. Mild low potassium does not typically cause symptoms. Symptoms may include feeling tired, leg cramps, weakness, and constipation. Low potassium also increases the risk of an abno ...
and
hypomagnesemia Magnesium deficiency is an electrolyte disturbance in which there is a low level of magnesium in the body. It can result in multiple symptoms. Symptoms include tremor, poor coordination, muscle spasms, loss of appetite, personality changes, an ...
, can cause anomalies in the electrical activity of the heart, and result in life-threatening arrhythmias. Hypokalemia most commonly results in patients with anorexia when restricting is accompanied by purging (induced vomiting or laxative use). Hypotension (low blood pressure) is common, and symptoms include fatigue and weakness. Orthostatic hypotension, a marked decrease in blood pressure when standing from a supine position, may also occur. Symptoms include lightheadedness upon standing, weakness, and cognitive impairment, and may result in
fainting Syncope, commonly known as fainting, or passing out, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. It is caused by a decrease in blood flow to the brain, typically from ...
or near-fainting. Orthostasis in anorexia nervosa indicates worsening cardiac function and may indicate a need for hospitalization. Hypotension and orthostasis generally resolve upon recovery to a normal weight. The weight loss in anorexia nervosa also causes
atrophy Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply t ...
of cardiac muscle. This leads to decreased ability to pump blood, a reduction in the ability to sustain exercise, a diminished ability to increase blood pressure in response to exercise, and a subjective feeling of fatigue. Some individuals may also have a decrease in cardiac contractility. Cardiac complications can be life-threatening, but the heart muscle generally improves with weight gain, and the heart normalizes in size over weeks to months, with recovery. Atrophy of the
heart muscle Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle tha ...
is a marker of the severity of the disease, and while it is reversible with treatment and refeeding, it is possible that it may cause permanent, microscopic changes to the heart muscle that increase the risk of sudden cardiac death. Individuals with anorexia nervosa may experience chest pain or
palpitations Palpitations are perceived abnormalities of the heartbeat characterized by awareness of cardiac muscle contractions in the chest, which is further characterized by the hard, fast and/or irregular beatings of the heart. Symptoms include a rapi ...
; these can be a result of mitral valve prolapse. Mitral valve prolapse occurs because the size of the heart muscle decreases while the tissue of the
mitral valve The mitral valve (), also known as the bicuspid valve or left atrioventricular valve, is one of the four heart valves. It has two cusps or flaps and lies between the left atrium and the left ventricle of the heart. The heart valves are all one-w ...
remains the same size. Studies have shown rates of mitral valve prolapse of around 20 percent in those with anorexia nervosa, while the rate in the general population is estimated at 2–4 percent. It has been suggested that there is an association between mitral valve prolapse and sudden cardiac death, but it has not been proven to be causative, either in patients with anorexia nervosa or in the general population.


Relapse

Rates of relapse after treatment range 30-72% over a period of 2-26 months, with a rate of approximately 50% in 12 months after weight restoration. Relapse occurs in approximately a third of people in hospital, and is greatest in the first six to eighteen months after release from an institution. BMI or measures of body fat and leptin levels at discharge were the strongest predictors of relapse, as well as signs of eating psychopathology at discharge. Duration of illness, age, severity, the proportion of AN binge-purge subtype, and presence of comorbidities are also contributing factors.


Epidemiology

Anorexia is estimated to occur in 0.9% to 4.3% of women and 0.2% to 0.3% of men in Western countries at some point in their life. About 0.4% of young females are affected in a given year and it is estimated to occur three to ten times less commonly in males. Rates in most of the developing world are unclear. Often it begins during the teen years or young adulthood. Medical students are a high risk group, with an overall estimated prevalence of 10.4% globally. The lifetime rate of atypical anorexia nervosa, a form of
ED-NOS Unspecified feeding or eating disorder (UFED) is a DSM-5 category of eating disorders that, along with other specified feeding or eating disorder (OSFED), replaced eating disorder not otherwise specified (EDNOS) in the DSM-IV-TR. UFED is an ea ...
in which the person loses a significant amount of weight and is at risk for serious medical complications despite having a higher body-mass index, is much higher, at 5–12%. While anorexia became more commonly diagnosed during the 20th century it is unclear if this was due to an increase in its frequency or simply better diagnosis. Most studies show that since at least 1970 the incidence of AN in adult women is fairly constant, while there is some indication that the incidence may have been increasing for girls aged between 14 and 20.


Underrepresentation

Eating disorders are less reported in preindustrial, non-westernized countries than in Western countries. In Africa, not including South Africa, the only data presenting information about eating disorders occurs in case reports and isolated studies, not studies investigating prevalence. Western countries experience slightly higher rates of eating disorders than non-western countries. Theories to explain these lower rates of eating disorders, lower reporting and lower research rates in include the effects of
westernisation Westernization (or Westernisation), also Europeanisation or occidentalization (from the ''Occident''), is a process whereby societies come under or adopt Western culture in areas such as industry, technology, science, education, politics, economi ...
, and
culture change Culture change is a term used in public policy making that emphasizes the influence of cultural capital on individual and community behavior. It has been sometimes called repositioning of culture, which means the reconstruction of the cultural conce ...
. Men (and women) who might otherwise be diagnosed with anorexia may not meet the
DSM-IV The ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM; latest edition: DSM-5-TR, published in March 2022) is a publication by the American Psychiatric Association (APA) for the classification of mental disorders using a common langua ...
criteria for BMI since they have muscle weight, but have very little fat. In many cases a subclinical "not otherwise specified" diagnosis is made instead; ED-NOS in the DSM-IV, and
other specified feeding or eating disorder Other specified feeding or eating disorder (OSFED) is a subclinical DSM-5 category that, along with unspecified feeding or eating disorder (UFED), replaces the category formerly called eating disorder not otherwise specified (EDNOS) in the DSM-I ...
or
unspecified feeding or eating disorder Unspecified feeding or eating disorder (UFED) is a DSM-5 category of eating disorders that, along with other specified feeding or eating disorder (OSFED), replaced eating disorder not otherwise specified (EDNOS) in the DSM-IV-TR. UFED is an ea ...
in the
DSM-5 The ''Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition'' (DSM-5), is the 2013 update to the ''Diagnostic and Statistical Manual of Mental Disorders'', the taxonomic and diagnostic tool published by the American Psychiatric ...
. ED-NOS was the most diagnosed eating disorder in 2009, and it was also shown that AN did not differ significantly in eating pathology or general psychopathology from EDNOS involving restrictive eating. The elderly population is increasingly experiencing anorexia nervosa, which has been termed the "Anorexia of Aging". The eating disorder is similar to that of typical anorexia nervosa but is more often accompanied by the overuse of laxatives in order to purge the individual of ingested food. Most geriatric anorexia patients limit their food intake to dairy or grains, whereas an adolescent anorexic has a more general limitation. This eating disorder that affects older adults has two types - early onset and late onset. Early onset refers to a recurrence of anorexia in late life in an individual who experienced the disease during their youth. Late onset describes instances where the eating disorder begins for the first time late in life. The stimulus for anorexia in elderly patients is typically a loss of control over their lives, which can be brought on by many events, including moving into an assisted living facility. This is also a time when most older individuals experience a rise in conflict with family members, such as limitations on driving or limitations on personal freedom, which increases the likelihood of an issue with anorexia. There can be physical issues in the elderly that leads to anorexia of aging, including a decline in chewing ability, a decline in taste and smell, and a decrease in appetite. Psychological reasons for the elderly to develop anorexia can include depression and bereavement, and even an indirect attempt at suicide. There are also common comorbid psychiatric conditions with aging anorexics, including major depression, anxiety disorder, obsessive compulsive disorder, bipolar disorder, schizophrenia, and
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
. The signs and symptoms that go along with anorexia of aging are similar to what is observed in adolescent anorexia, including sudden weight loss, unexplained hair loss or dental problems, and a desire to eat alone. There are also several medical conditions that can result from anorexia in the elderly. An increased risk of illness and death can be a result of anorexia. There is also a decline in muscle and bone mass as a result of a reduction in protein intake during anorexia. Another result of anorexia in the aging population is irreparable damage to kidneys, heart or colon and an imbalance of electrolytes. Many assessments are available to diagnose anorexia in the aging community. These assessments include th
Simplified Nutritional Assessment Questionnaire
(SNAQ) an
Functional Assessment of Anorexia/Cachexia Therapy
(FAACT). Specific to the geriatric populace, th
interRAI
system identifies detrimental conditions in assisted living facilities and nursing homes. Even a simple screening for nutritional insufficiencies such as low levels of important vitamins, can help to identify someone who has anorexia of aging. Anorexia in the elderly should be identified by the
retirement communities A retirement community is a residential community or housing complex designed for older adults who are generally able to care for themselves; however, assistance from home care agencies is allowed in some communities, and activities and socializ ...
but is often overlooked, especially in patients with
dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...
. Some studies report that malnutrition is prevalent in nursing homes, with up to 58% of residents suffering from it, which can lead to the difficulty of identifying anorexia. One of the challenges with assisted living facilities is that they often serve bland, monotonous food, which lessens residents desire to eat. The treatment for anorexia of aging is undifferentiated as anorexia for any other age group. Some of the treatment options include outpatient and inpatient facilities, antidepressant medication and behavioral therapy such as meal observation and discussing eating habits. Male and female athletes are often overlooked as anorexic. Research emphasizes the importance to take athletes' diet, weight and symptoms into account when diagnosing anorexia, instead of just looking at weight and BMI. For athletes, ritualized activities such as weigh-ins place emphasis on gaining and losing large amounts of weight, which may promote the development of eating disorders among them. While women use diet pills, which is an indicator of unhealthy behavior and an eating disorder, men use steroids, which contextualizes the beauty ideals for genders. In a Canadian study, 4% of boys in grade nine used
anabolic steroids Anabolic steroids, also known more properly as anabolic–androgenic steroids (AAS), are steroidal androgens that include natural androgens like testosterone as well as synthetic androgens that are structurally related and have similar effects t ...
. Anorexic men are sometimes referred to as ''manorexic''.


History

The history of anorexia nervosa begins with descriptions of religious fasting dating from the
Hellenistic era In Classical antiquity, the Hellenistic period covers the time in Mediterranean history after Classical Greece, between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire, as signified by the Battle of Actium in 3 ...
and continuing into the medieval period. The medieval practice of self-starvation by women, including some young women, in the name of religious piety and purity also concerns anorexia nervosa; it is sometimes referred to as ''
anorexia mirabilis Anorexia mirabilis, also known as holy anorexia or inedia prodigiosa or colloquially as fasting girls, is an eating disorder, similar to that of anorexia nervosa, that was common in, but not restricted to, the Middle Ages in Europe, largely affec ...
.'' The earliest medical descriptions of anorexic illnesses are generally credited to English physician Richard Morton in 1689. Case descriptions fitting anorexic illnesses continued throughout the 17th, 18th, and 19th centuries. The term "anorexia nervosa" was coined in 1873 by Sir William Gull, one of
Queen Victoria Victoria (Alexandrina Victoria; 24 May 1819 – 22 January 1901) was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until Death and state funeral of Queen Victoria, her death in 1901. Her reign of 63 years and 21 ...
's personal physicians. Gull published a seminal paper providing a number of detailed case descriptions of patients with anorexia nervosa. In the same year, French physician Ernest-Charles Lasègue similarly published details of a number of cases in a paper entitled ''De l'Anorexie hystérique''. See also In the late 19th century anorexia nervosa became widely accepted by the medical profession as a recognized condition. Awareness of the condition was largely limited to the medical profession until the latter part of the 20th century, when German-American psychoanalyst
Hilde Bruch Hilde Bruch (March 11, 1904 December 15, 1984) was a German-born American psychiatrist and psychoanalyst, known foremost for her work on eating disorders and obesity. Bruch emigrated to the United States in 1934. She worked and studied at v ...
published ''The Golden Cage: the Enigma of Anorexia Nervosa'' in 1978. Despite major advances in neuroscience, Bruch's theories tend to dominate popular thinking. A further important event was the death of the popular singer and drummer
Karen Carpenter Karen Anne Carpenter (March 2, 1950 – February 4, 1983) was an American singer and drummer, who formed half of the sibling duo the Carpenters alongside her older brother Richard. With a distinctive three-octave contralto range, she was prais ...
in 1983, which prompted widespread ongoing media coverage of eating disorders.


See also

*
Body image disturbance Body image disturbance (BID) is a common symptom in patients with eating disorders and is characterized by an altered perception of one's own body. The onset is mainly attributed to patients with anorexia nervosa who persistently tend to sub ...
*
Body image Body image is a person's thoughts, feelings and perception of the aesthetics or sexual attractiveness of their own body. The concept of body image is used in a number of disciplines, including neuroscience, psychology, medicine, psychiatry, ps ...
* Eating recovery *
Evolutionary psychiatry Evolutionary psychiatry, also known as Darwinian psychiatry, is a theoretical approach to psychiatry that aims to explain psychiatric disorders in evolutionary terms. A branch of the field of evolutionary medicine, it is distinct from the medical p ...
* Idée fixe *
Inedia Inedia (Latin for 'fasting') or breatharianism () is the claimed ability for a person to live without consuming food, and in some cases water. It is a deadly pseudoscience and several adherents of these practices have died from starvation or deh ...
*
List of people with anorexia nervosa This is a list of notable people who had anorexia nervosa. Often simply known as anorexia, this is an eating disorder which is characterized by an obsessive fear of gaining weight, weight loss, and distorted body image. People with anorexia usuall ...
* National Association of Anorexia Nervosa and Associated Disorders *
Orthorexia nervosa Orthorexia nervosa (also known as orthorexia) (ON) is a proposed eating disorder characterized by an excessive preoccupation with eating healthy food. The term was introduced in 1997 by American physician Steven Bratman, M.D. He suggested that som ...
*
Pro-ana Promotion of anorexia is the promotion of behaviors related to the eating disorder anorexia nervosa. It is often referred to simply as pro-ana or ana. The lesser-used term pro-mia refers likewise to bulimia nervosa and is sometimes used interchan ...


References


Further reading

* * *


External links


National Association of Anorexia Nervosa and Associated Disorders

Society of Clinical Psychology—Anorexia
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