Anhedonia is a diverse array of deficits in
hedonic
Hedonism refers to a family of theories, all of which have in common that pleasure plays a central role in them. ''Psychological'' or ''motivational hedonism'' claims that human behavior is determined by desires to increase pleasure and to decre ...
function, including reduced motivation or ability to experience pleasure.
While earlier definitions emphasized the inability to experience pleasure, anhedonia is currently used by researchers to refer to reduced motivation, reduced anticipatory pleasure (wanting), reduced consummatory pleasure (liking), and deficits in
reinforcement learning
Reinforcement learning (RL) is an area of machine learning concerned with how intelligent agents ought to take actions in an environment in order to maximize the notion of cumulative reward. Reinforcement learning is one of three basic machine ...
.
In the ''
'' (DSM-5
), anhedonia is a component of depressive disorders, substance-related disorders, psychotic disorders, and personality disorders, where it is defined by either a reduced ability to experience pleasure, or a diminished interest in engaging in pleasurable activities.
While the
''International Statistical Classification of Diseases and Related Health Problems, Tenth Revision'' (ICD-10) does not explicitly mention anhedonia, the depressive symptom analogous to anhedonia as described in the DSM-5 is a loss of interest or pleasure.
Definition
While anhedonia was originally defined in 1896 by
Théodule-Armand Ribot
Théodule-Armand Ribot (18 December 18399 December 1916) was a French psychologist. He was born at Guingamp, and was educated at the Lycée de St Brieuc. He is known as the founder of scientific psychology in France, and gave his name to Ribot's ...
as the reduced ability to experience pleasure, it has been used to refer to deficits in multiple facets of reward. Re-conceptualizations of anhedonia highlight the independence of "wanting" and "liking". "Wanting" is a component of anticipatory positive affect, mediating both the motivation (i.e. incentive salience) to engage with reward, as well as the positive emotions associated with anticipating a reward. "Liking", on the other hand, is associated with the pleasure derived from consuming a reward.
The consciousness of reward-related processes has also been used to categorize reward in the context of anhedonia, as studies comparing implicit behavior versus explicit self-reports demonstrate a dissociation of the two.
Learning has also been proposed as an independent facet of reward that may be impaired in conditions associated with anhedonia, but empirical evidence dissociating learning from either "liking" or "wanting" is lacking.
Anhedonia has also been used to refer to "affective blunting", "restricted range of affect", "emotional numbing", and "flat affect", particularly in the context of
post-traumatic stress disorders
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 ...
. In PTSD patients, scales measuring these symptoms correlate strongly with scales that measure more traditional aspects of anhedonia, supporting this association.
Causes
Studies in clinical populations, healthy populations, and animal models have implicated a number of neurobiological substrates in anhedonia. Regions implicated in anhedonia include the
prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...
as a whole, particularly the
orbitofrontal cortex (OFC), 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 ...
,
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...
,
anterior cingulate cortex (ACC),
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 ...
, and
ventral tegmental area (VTA).
Neuroimaging studies in humans have reported that deficits in consummatory aspects of reward are associated with abnormalities in the ventral striatum and medial prefrontal cortex, while deficits in anticipatory aspects of reward are related to abnormalities in hippocampal, dorsal ACC and prefrontal regions. These abnormalities are generally consistent with animal models, except for inconsistent findings with regard to the OFC. This inconsistency may be related to the difficulty in imaging the OFC due to its anatomical location, or the small number of studies performed on anhedonia; a number of studies have reported reduced activity in the OFC in schizophrenia and major depression, as well as a direct relationship between reduced activity and anhedonia.
Researchers theorize that anhedonia may result from the breakdown in the
brain's reward system, involving the
neurotransmitter
A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell.
Neuro ...
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 ...
. Anhedonia can be characterised as "impaired ability to pursue, experience and/or learn about pleasure, which is often, but not always accessible to conscious awareness".
The conditions of
akinetic mutism
Akinetic mutism is a medical term describing patients tending neither to move (akinesia) nor speak (mutism). Akinetic mutism was first described in 1941 as a mental state where patients lack the ability to move or speak. However, their eyes may fo ...
and
negative symptoms
Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...
are closely related. In akinetic mutism, a stroke or other lesion to the anterior cingulate cortex causes reduction in movement (akinetic) and speech (mutism).
Occurrence
Major depressive disorder
Anhedonia occurs in roughly 70% of people with a major depressive disorder.
Anhedonia is a core symptom of
major depressive disorder
Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introdu ...
; therefore, individuals experiencing this symptom can be diagnosed with depression, even in the absence of low/depressed mood. The Diagnostic and Statistical Manual of Mental Disorders (DSM) describes a "lack of interest or pleasure", but these can be difficult to discern given that people tend to become less interested in things which do not give them pleasure. The DSM criterion of weight loss is probably related, and many individuals with this symptom describe a lack of enjoyment of food. They can portray any of the non-psychotic symptoms and signs of depression.
Schizophrenia
Anhedonia is one of the
negative symptoms
Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...
of
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 ...
.
Although five domains are usually used to classify negative symptoms, factor analysis of questionnaires yield two factors, with one including deficits in pleasure and motivation. People with schizophrenia retrospectively report experiencing fewer positive emotions than healthy individuals. However, "liking" or consummatory pleasure, is intact in people with schizophrenia, as they report experiencing the same degree of positive affect when presented with rewarding stimuli. Neuroimaging studies support this behavioral observation, as most studies report intact responses in the reward system (i.e. ventral striatum, VTA) to simple rewards. However, studies on monetary rewards sometimes report reduced responsiveness. More consistent reductions are observed with regard to emotional response during reward anticipation, which is reflected in a reduced responsiveness of both cortical and subcortical components of the reward system. Schizophrenia is associated with reduced positive prediction errors (a normal pattern of response to an unexpected reward), which a few studies have demonstrated to be correlated with negative symptoms. People with schizophrenia demonstrate impairment in reinforcement learnings tasks only when the task requires explicit learning, or is sufficiently complex. Implicit reinforcement learning, on the other hand, is relatively intact. These deficits may be related to dysfunction in the ACC, OFC and dlPFC leading to abnormal representation of reward and goals.
Substance-related disorders
Anhedonia is common in people who are dependent upon any one or more of a wide variety of drugs, including
alcohol,
opioids
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
, and
nicotine
Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...
. Although anhedonia becomes less severe over time, it is a significant predictor of relapse.
Post-traumatic stress disorder
While PTSD is associated with reduced motivation, part of the anticipatory "wanting", it is also associated with elevated sensation seeking, and no deficits in physiological arousal, or self reported pleasure to positive stimuli. PTSD is also associated with blunted affect, which may be due to the high comorbidity with depression.
Parkinson's disease
Anhedonia occurs frequently in
Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...
, with rates between 7%–45% being reported. Whether or not anhedonia is related to the high rates of depression in Parkinson's disease is unknown.
Bipolar depression
Anhedonia is also reported to appear in people with
bipolar depression
Bipolar disorder, previously known as manic depression, is a mental disorder characterized by periods of depression and periods of abnormally elevated mood that last from days to weeks each. If the elevated mood is severe or associated with ...
.
Attention deficit hyperactivity disorder
Anhedonia may be associated with
ADHD
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-inapp ...
. Impairments of
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 ...
rgic and
serotonergic
Serotonergic () or serotoninergic () means "pertaining to or affecting serotonin". Serotonin is a neurotransmitter. A synapse is serotonergic if it uses serotonin as its neurotransmitter. A serotonergic neuron ''produces'' serotonin. A substance is ...
function in the brain of those with ADHD result in dysregulation of reward processing which can lead to anhedonia.
Sexual anhedonia
Sexual anhedonia in males is also known as 'ejaculatory anhedonia'. This condition means that the man will
ejaculate
Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the male reproductory tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component ...
with no accompanying sense of pleasure.
The condition is most frequently found in males, but women can experience lack of pleasure when the body goes through the
orgasm
Orgasm (from Greek , ; "excitement, swelling") or sexual climax is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic, involuntary muscular contractions in the pelvic region charac ...
process as well.
Sexual anhedonia may be caused by:
*
Hyperprolactinaemia
Hyperprolactinaemia is the presence of abnormally high levels of prolactin in the blood. Reference ranges for common blood tests, Normal levels average to about 13 ng/mL in women, and 5 ng/mL in men, with an upper normal limit of serum ...
* Hypoactive sexual desire disorder (HSDD), also called
inhibited sexual desire
* Low levels of the hormone
testosterone
Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...
* Spinal cord injury
*
Multiple sclerosis
Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This d ...
* Use of
SSRI
Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder, anxiety disorders, and other psychological conditions.
SSRIs increase the extracellul ...
antidepressants or having used SSRI antidepressants in the past.
* Use (or previous use) of antidopaminergic neuroleptics (
anti-psychotics)
* Fatigue
* Physical illness
It is very uncommon that a neurological examination and blood tests can determine the cause of a specific case of sexual anhedonia.
Patients may be prescribed sustained-release
bupropion to aid in treatment, which has been shown to relieve sexual dysfunction even in patients without depression.
Social anhedonia
Definition
''Social anhedonia'' is defined as a disinterest in social contact and a lack of pleasure in social situations, and is characterized by social withdrawal. This characteristic typically manifests as an indifference to other people.
In contrast to
introversion
The traits of extraversion (also spelled extroversion Retrieved 2018-02-21.) and introversion are a central dimension in some human personality theories. The terms ''introversion'' and ''extraversion'' were introduced into psychology by Carl ...
, a nonpathological dimension of human personality, social anhedonia represents a deficit in the ability to experience
pleasure
Pleasure refers to experience that feels good, that involves the enjoyment of something. It contrasts with pain or suffering, which are forms of feeling bad. It is closely related to value, desire and action: humans and other conscious anima ...
.
Additionally, social anhedonia differs from
social anxiety
Social anxiety is the anxiety and fear specifically linked to being in social settings (i.e., interacting with others). Some categories of disorders associated with social anxiety include anxiety disorders, mood disorders, autism spectrum disord ...
in that social anhedonia is predominantly typified by diminished positive affect, while social anxiety is distinguished by both decreased
positive affect
Positive affectivity (PA) is a human characteristic that describes how much people experience positive affects (sensations, emotions, sentiments); and as a consequence how they interact with others and with their surroundings.
People with high po ...
and exaggerated
negative affect
Negative affectivity (NA), or negative affect, is a personality variable that involves the experience of negative emotions and poor self-concept. Negative affectivity subsumes a variety of negative emotions, including anger, contempt, disgust, g ...
.
This trait is currently seen as a central characteristic, as well as a predictor, of
schizophrenia spectrum disorders
A spectrum disorder is a mental disorder that includes a range of linked conditions, sometimes also extending to include singular symptoms and trait theory, traits. The different elements of a spectrum either have a similar appearance or are though ...
.
Signs and symptoms
* Decreased ability to experience interpersonal pleasure
* Social withdrawal/isolation
* Decreased capacity for social contact and interaction
* Lack of close friends and intimate relationships, and decreased quality of those relationships
* Poor social adjustment
* Decreased positive affect
*
Flat affect
Reduced affect display, sometimes referred to as emotional blunting or emotional numbing, is a condition of reduced emotional reactivity in an individual. It manifests as a failure to express feelings ( affect display) either verbally or nonverba ...
*
Depressed mood
Depression is a mental state of low mood and aversion to activity, which affects more than 280 million people of all ages (about 3.5% of the global population). Classified medically as a mental and behavioral disorder, the experience of ...
* State-related anxiety
[
]
Background and early clinical observation
The term ''anhedonia'' is derived from the Greek ''an-'', "without" and ''hēdonē'', "pleasure". Interest in the nature of pleasure and its absence dates back to ancient Greek philosophers such as Epicurus
Epicurus (; grc-gre, Ἐπίκουρος ; 341–270 BC) was an ancient Greek philosopher and sage who founded Epicureanism, a highly influential school of philosophy. He was born on the Greek island of Samos to Athenian parents. Influenced ...
. The symptoms of anhedonia were introduced to the realm of psychopathology in 1809 by John Haslam
Sir John Haslam (27 February 1878 – 21 May 1940) was a Conservative Party politician in England. He was the Member of Parliament (MP) for Bolton
Bolton (, locally ) is a large town in Greater Manchester in North West England, forme ...
, who characterized a patient with schizophrenia as indifferent to "those objects and pursuits which formerly proved sources of delight and instruction". The concept was formally coined by Théodule-Armand Ribot
Théodule-Armand Ribot (18 December 18399 December 1916) was a French psychologist. He was born at Guingamp, and was educated at the Lycée de St Brieuc. He is known as the founder of scientific psychology in France, and gave his name to Ribot's ...
and later used by psychiatrists Paul Eugen Bleuler and Emil Kraepelin
Emil Wilhelm Georg Magnus Kraepelin (; ; 15 February 1856 – 7 October 1926) was a German psychiatrist.
H. J. Eysenck's ''Encyclopedia of Psychology'' identifies him as the founder of modern scientific psychiatry, psychopharmacology and psych ...
to describe a core symptom of schizophrenia. In particular, Rado postulated that schizotypes, or individuals with the schizophrenic phenotype, have two key genetic deficits, one related to the ability to feel pleasure (anhedonia) and one related to proprioception
Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense".
Proprioception is mediated by proprioceptors, mechanosensory neurons ...
. In 1962 Meehl furthered Rado's theory through the introduction of the concept of schizotaxia, a genetically driven neural integrative defect thought to give rise to the personality type of schizotypy
In psychology, schizotypy is a theoretical concept that posits a continuum of personality characteristics and experiences, ranging from normal dissociative, imaginative states to extreme states of mind related to psychosis, especially schizophreni ...
. Loren and Jean Chapman further distinguished between two types of anhedonia: physical anhedonia, or a deficit in the ability to experience physical pleasure, and social, or a deficit in the ability to experience interpersonal pleasure.
Recent research suggests that social anhedonia may represent a prodrome
In medicine, a prodrome is an early sign or symptom (or set of signs and symptoms) that often indicates the onset of a disease before more diagnostically specific signs and symptoms develop. It is derived from the Greek word ''prodromos'', meanin ...
of psychotic disorders.[ First-degree relatives of individuals with schizophrenia show elevated levels of social anhedonia, higher baseline scores of social anhedonia are associated with later development of schizophrenia.] These findings provide support for the conjecture that it represents a genetic risk marker for schizophrenia-spectrum disorders.
Additionally, elevated levels of social anhedonia in patients with schizophrenia have been linked to poorer social functioning. Socially anhedonic individuals perform worse on a number of neuropsychological tests than non-anhedonic participants, and show similar physiological abnormalities seen in patients with schizophrenia.
Comorbidity
Anhedonia is present in several forms of psychopathology.
Depression
Social anhedonia is observed in both depression and schizophrenia. However, social anhedonia is a state related to the depressive episode and the other is trait related to the personality construct associated with schizophrenia. These individuals both tend to score highly on self-report measures of social anhedonia. Blanchard, Horan, and Brown demonstrated that, although both the depression and the schizophrenia patient groups can look very similar in terms of social anhedonia cross-sectionally, over time as individuals with depression experience symptom remission, they show fewer signs of social anhedonia, while individuals with schizophrenia do not. Blanchard and colleagues (2011) found individuals with social anhedonia also had elevated rates of lifetime mood disorders including depression and dysthymia
Dysthymia ( ), also known as persistent depressive disorder (PDD), is a mental and behavioral disorder, specifically a disorder primarily of mood, consisting of similar cognitive and physical problems as major depressive disorder, but with lo ...
compared to controls.
Social anxiety
As mentioned above, social anxiety and social anhedonia differ in important ways. However, social anhedonia and social anxiety are also often comorbid. People with social anhedonia may display increased social anxiety and be at increased risk for social phobias and generalized anxiety disorder. It has yet to be determined what the exact relationship between social anhedonia and social anxiety is, and if one potentiates the other. Individuals with social anhedonia may display increased stress reactivity, meaning that they feel more overwhelmed or helpless in response to a stressful event compared to control subjects who experience the same type of stressor. This dysfunctional stress reactivity may correlate with hedonic capacity, providing a potential explanation for the increased anxiety symptoms experienced in people with social anhedonia. In an attempt to separate out social anhedonia from social anxiety, the Revised Social Anhedonia Scale[Eckblad, M.L., Chapman, L.J., Chapman, J.P., & Mishlove, M. (1982)]
The Revised Social Anhedonia Scale
. Unpublished test didn't include items that potentially targeted social anxiety. However, more research must be conducted on the underlying mechanisms through which social anhedonia overlaps and interacts with social anxiety. The efforts of the "social processes" RDoC initiative will be crucial in differentiating between these components of social behavior that may underlie mental illnesses 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 ...
.
Primary relevance in schizophrenia and schizophrenia spectrum disorders
Social anhedonia is a core characteristic of schizotypy
In psychology, schizotypy is a theoretical concept that posits a continuum of personality characteristics and experiences, ranging from normal dissociative, imaginative states to extreme states of mind related to psychosis, especially schizophreni ...
, which is defined as a continuum of personality traits that can range from normal to disordered and contributes to risk for psychosis
Psychosis is a condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior ...
and 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 ...
. Social anhedonia is a dimension of both negative and positive schizotypy. It involves social and interpersonal deficits, but is also associated with cognitive slippage and disorganized speech, both of which fall into the category of positive schizotypy. Not all people with schizophrenia display social anhedonia and likewise, people who have social anhedonia may never be diagnosed with a schizophrenia-spectrum disorder if they do not have the positive and cognitive symptoms that are most frequently associated with most schizophrenia-spectrum disorders.
Social anhedonia may be a valid predictor of future schizophrenia-spectrum disorders; young adults with social anhedonia perform in a similar direction to schizophrenia patients in tests of cognition and social behavior, showing potential predictive validity. Social anhedonia usually manifests in adolescence, possibly because of a combination of the occurrence of critical neuronal development and synaptic pruning of brain regions important for social behavior and environmental changes, when adolescents are in the process of becoming individuals and gaining more independence.
Treatment
There is no validated treatment for social anhedonia.[ Future research should focus on genetic and environmental risk factors to home in on specific brain regions and neurotransmitters that may be implicated in social anhedonia's cause and could be targeted with medication or behavioral treatments. Social support may also play a valuable role in the treatment of social anhedonia. Blanchard et al.] found that a greater number of social supports, as well as a greater perceived social support network, were related to fewer schizophrenia-spectrum symptoms and to better general functioning within the social anhedonia group. So far, no medicine has been developed to specifically target anhedonia.
Gender differences
In the general population, males score higher than females on measures of social anhedonia. This sex difference is stable throughout time (from adolescence into adulthood) and is also seen in people with schizophrenia-spectrum disorders. These results may reflect a more broad pattern of interpersonal and social deficits seen in schizophrenia-spectrum disorders. On average, males with schizophrenia are diagnosed at a younger age, have more severe symptoms, worse treatment prognosis, and a decrease in overall quality of life compared to females with the disorder. These results, coupled with the sex difference seen in social anhedonia, outline the necessity for research on genetic and hormonal characteristics that differ between males and females, and that may increase risk or resilience for mental illnesses such as schizophrenia.
Assessing social anhedonia
There are several self-report psychometric measures of schizotypy
In psychology, schizotypy is a theoretical concept that posits a continuum of personality characteristics and experiences, ranging from normal dissociative, imaginative states to extreme states of mind related to psychosis, especially schizophreni ...
which each contain subscales related to social anhedonia:
* Revised Social Anhedonia Scale—Chapman Psychosis Proneness Scales
* No Close Friends Subscale – Schizotypal Personality Questionnaire
* Introverted Anhedonia Subscale— Oxford–Liverpool Inventory of Feelings and Experiences
Genetic components
L.J. and J.P. Chapman were the first to discuss the possibility that social anhedonia may stem from a genetic vulnerability. The ''disrupted in schizophrenia 1'' (''DISC1'') gene has been consistently associated with risk for, and cause of, schizophrenia-spectrum disorders and other mental illnesses. More recently, DISC1
Disrupted in schizophrenia 1 is a protein that in humans is encoded by the ''DISC1'' gene. In coordination with a wide array of interacting partners, DISC1 has been shown to participate in the regulation of cell proliferation, differentiation, m ...
has been associated with social anhedonia within the general population. Tomppo identified a specific DISC1 allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution.
::"The chro ...
that is associated with an increase in characteristics of social anhedonia. They also identified a DISC1 allele associated with decreased characteristics of social anhedonia, that was found to be preferentially expressed in women. More research needs to be conducted, but social anhedonia may be an important intermediate phenotype (endophenotype In genetic epidemiology, endophenotype (or intermediate phenotype) is a term used to separate behavioral symptoms into more stable phenotypes with a clear genetic connection. The concept was coined by Bernard John and Kenneth R. Lewis in a 1966 pap ...
) between genes associated with risk for schizophrenia and phenotype of the disorder.
Neurobiological correlates
Researchers studying the neurobiology of social anhedonia posit that this trait may be linked to dysfunction of reward-related systems in the brain. This circuitry is critical for the sensation of pleasure, the computation of reward benefits and costs, determination of the effort required to obtain a pleasant stimulus, deciding to obtain that stimulus, and increasing motivation to obtain the stimulus. In particular, the ventral striatum and areas of the prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...
(PFC), including the 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 ...
(OFC) and dorsolateral (dl) PFC, are critically involved in the experience of pleasure and the hedonic
Hedonism refers to a family of theories, all of which have in common that pleasure plays a central role in them. ''Psychological'' or ''motivational hedonism'' claims that human behavior is determined by desires to increase pleasure and to decre ...
perception of rewards. With regards to neurotransmitter systems, opioid
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid us ...
, gamma-Aminobutyric acid and endocannabinoid systems in the nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for " nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypot ...
, ventral pallidum
The ventral pallidum (VP) is a structure within the basal ganglia of the brain. It is an output nucleus whose fibres project to thalamic nuclei, such as the ventral anterior nucleus, the ventral lateral nucleus, and the medial dorsal nucleus.
The ...
, and OFC mediate the hedonic perception of rewards. Activity in the PFC and ventral striatum have been found to be decreased in anhedonic individuals with major depressive disorder
Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Introdu ...
(MDD) and 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 ...
. However, schizophrenia may be less associated with decreased hedonic capacity and more with deficient reward appraisal.
Specific musical anhedonia
Recent studies have found people who do not have any issue processing musical tones or beat, yet receive no pleasure from listening to music. Specific musical anhedonia is distinct from melophobia, the fear of music.
See also
* Avolition
Avolition, as a symptom of various forms of psychopathology, is the decrease in the ability to initiate and persist in self-directed purposeful activities. Such activities that appear to be neglected usually include routine activities, including h ...
* Dysthymia
Dysthymia ( ), also known as persistent depressive disorder (PDD), is a mental and behavioral disorder, specifically a disorder primarily of mood, consisting of similar cognitive and physical problems as major depressive disorder, but with lo ...
References
External links
Anhedonia – Bipolar Disorder Symptoms
{{Authority control
Symptoms and signs of mental disorders
Mood disorders
Major depressive disorder
Pleasure