Relatively speaking, the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...
consumes an immense amount of energy in comparison to the rest of the body. The mechanisms involved in the transfer of energy from foods to neurons are likely to be fundamental to the control of brain function.
Human bodily processes, including the brain, all require both
macronutrients
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excre ...
, as well as
micronutrients
Micronutrients are essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for example, huma ...
.
Insufficient intake of selected vitamins, or certain metabolic disorders, may affect
cognitive processes
Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
by disrupting the nutrient-dependent processes within the body that are associated with the management of energy in neurons, which can subsequently affect
synaptic plasticity
In neuroscience, synaptic plasticity is the ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity. Since memories are postulated to be represented by vastly interconnected neural circuits ...
, or the ability to encode new
memories
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
.
Macronutrients
The human brain requires
nutrients obtained from the diet to develop and sustain its physical structure and
cognitive functions
Cognitive skills, also called cognitive functions, cognitive abilities or cognitive capacities, are brain-based skills which are needed in acquisition of knowledge, manipulation of information and reasoning. They have more to do with the mechanisms ...
.
Additionally, the brain requires
caloric energy predominately derived from the primary
macronutrients
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excre ...
to operate.
The three primary macronutrients include
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...
s,
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, res ...
s, and
fat
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple est ...
s. Each macronutrient can impact
cognition through multiple mechanisms, including glucose and insulin metabolism, neurotransmitter actions, oxidative stress and inflammation, and the gut-brain axis.
Inadequate macronutrient consumption or proportion could impair optimal cognitive functioning and have long term health implications.
Carbohydrates
Through digestion, dietary
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...
s are broken down and converted into
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
, which is the sole energy source for the brain.
Optimal brain function relies on adequate carbohydrate consumption, as carbohydrates provide the quickest source of glucose for the brain.
Glucose deficiencies such as
hypoglycaemia
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 bel ...
reduce available energy for the brain and impair all cognitive processes and performance.
Additionally, situations with high cognitive demand, such as learning a new task, increase brain glucose utilization, depleting blood glucose stores and initiating the need for supplementation.
Complex carbohydrates
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may ...
, especially those with high
dietary fibre
Dietary fiber (in British English fibre) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition, and can be grouped generally by th ...
, are associated with increased cognitive performance and improved memory function.
This is because fibre regulates glucose metabolism, slowing the release of
insulin and preserving
insulin sensitivity
Insulin resistance (IR) is a pathological condition in which cells fail to respond normally to the hormone insulin.
Insulin is a hormone that facilitates the transport of glucose from blood into cells, thereby reducing blood glucose (blood sugar) ...
.
An improperly functioning glucose and insulin metabolism is a primary mechanism for
cognitive impairment
Cognitive deficit is an inclusive term to describe any characteristic that acts as a barrier to the cognition process.
The term may describe
* deficits in overall intelligence (as with intellectual disabilities),
* specific and restricted defici ...
, and general
metabolic dysfunction
Metabolic syndrome is a clustering of at least three of the following five medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL).
Metabolic syndrom ...
, as it can cause inflammation and oxidative stress within the brain, potentially leading to
neurodegeneration.
Therefore, complex carbohydrates with high fibre can improve glucose and insulin metabolism, which decreases inflammation and oxidative stress, and leads to improved brain aging as measured by the absence of
disability
Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be cognitive, developmental, intellectual, mental, physical, ...
,
depression,
chronic disease
A chronic condition is a health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. The term ''chronic'' is often applied when the course of the disease lasts for more than three m ...
, and decreased
cognitive decline
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 affec ...
.
Simple carbohydrates
Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built.
They are usually colorless, water-solub ...
are associated with decreased global cognitive performance.
Simple carbohydrates negatively impact many essential cognitive processes, including
attention,
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...
,
reaction time
Mental chronometry is the scientific study of processing speed or reaction time on cognitive tasks to infer the content, duration, and temporal sequencing of mental operations. Reaction time (RT; sometimes referred to as "response time") is meas ...
, visual-spatial processing, mental processing speed, and
executive functions
In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and suc ...
.
Simple carbohydrates impair cognition through glucose and insulin metabolism dysfunction, as well as causing inflammation and oxidative stress within the brain.
Therefore, excessive or chronic consumption of simple carbohydrates is unanimously linked to negative health consequences.
Proteins
Through digestion dietary proteins are broken down into individual
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
s and absorbed into the blood.
The
essential amino acid
An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...
s
tyrosine
-Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...
and
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 ...
are precursors for the
neurotransmitters
dopamine,
serotonin, and
norepinephrine
Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad' ...
, and these chemicals modulate
neural activity and influence cognitive functioning.
Dietary protein can improve cognition by increasing reaction time and inhibition control during mentally demanding and physically stressful situations, as tyrosine and tryptophan will replenish exhausted neurotransmitter levels.
Additionally, adequate and consistent consumption of tyrosine and tryptophan correlates to improvements in memory function.
Tyrosine is also shown to improve
convergent thinking Convergent thinking is a term coined by Joy Paul Guilford as the opposite of divergent thinking. It generally means the ability to give the "correct" answer to standard questions that do not require significant creativity, for instance in most task ...
processes through increased
cognitive control
In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and suc ...
.
Insufficient and excessive protein consumption are both linked to decreased cognitive functioning and adverse health effects.
Studies indicate long term protein overconsumption can increase inflammation and oxidative stress which impairs cognitive functioning.
Excessive tyrosine consumption can also negatively impact short term working memory.
Due to an interrelation between serotonin and
melatonin high tryptophan levels can produce
sedative effects, decreasing
alertness
Alertness is the state of active attention by high sensory awareness such as being watchful and prompt to meet danger or emergency, or being quick to perceive and act. It is related for psychology . A lack of alertness is a symptom of a ...
and increasing sensations of
fatigue.
Fats
Through digestion dietary fats are broken down into individual
fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...
s for utilization. Fatty acids are classified as
saturated
Saturation, saturated, unsaturation or unsaturated may refer to:
Chemistry
* Saturation, a property of organic compounds referring to carbon-carbon bonds
** Saturated and unsaturated compounds
**Degree of unsaturation
** Saturated fat or fatty ac ...
,
trans
Trans- is a Latin prefix meaning "across", "beyond", or "on the other side of".
Used alone, trans may refer to:
Arts, entertainment, and media
* Trans (festival), a former festival in Belfast, Northern Ireland, United Kingdom
* ''Trans'' (fil ...
,
monounsaturated
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple est ...
,
polyunsaturated
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple es ...
, and
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 ...
. Each class has distinct affects on cognitive functioning and
health
Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...
.
Monounsaturated and polyunsaturated fatty acids are commonly found in avocados, vegetables, vegetable oils, olive oil, and fresh fish. These fatty acids are considered healthy and generally improve cognitive performance, executive function, memory performance, and promote long term brain health.
This is achieved through a variety of mechanisms, including enhancing
synaptic plasticity
In neuroscience, synaptic plasticity is the ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity. Since memories are postulated to be represented by vastly interconnected neural circuits ...
, promoting effective glucose utilization, and reducing inflammation and oxidative stress.
Omega-3 polyunsaturated fatty acids are especially significant as they are critical
cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
and structural components of the brain.
Cholesterol is an unsaturated alcohol commonly found in eggs, meat, and dairy. Studies on dietary cholesterol have indicated both positive and negative effects on global cognitive functioning.
However, the adverse cognitive effects of cholesterol consumption appear to be reduced when combined with physical activity, which influences
energy homeostasis In biology, energy homeostasis, or the homeostatic control of energy balance, is a biological process that involves the coordinated homeostatic regulation of food intake (energy inflow) and energy expenditure (energy outflow). The human brain, part ...
and synaptic plasticity.
Saturated fatty acids are typically solid at room temperature with common sources including butter, cheese, and meat. Trans fatty acids occur naturally in some meat and dairy products, however the majority are artificially created by
hydrogenating vegetable oils and are present in many
processed foods
Convenience food, also called tertiary processed food, is food that is commercially prepared (often through processing) to optimise ease of consumption. Such food is usually ready to eat without further preparation. It may also be easily por ...
. Saturated and trans fatty acids decrease cognitive functioning and specifically impact memory and learning performance.
These fatty acids initiate an immediate inflammatory response which can cause oxidative stress, neurodegeneration, and a reduction of
grey matter
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distingu ...
within the brain. Saturated and trans fatty acids are generally considered unhealthy for their universally adverse health implications.
Nutrients needed for memory development
Choline
Choline Choline is an essential nutrient for humans and many other animals. Choline occurs as a cation that forms various salts (X− in the depicted formula is an undefined counteranion). Humans are capable of some ''de novo synthesis'' of choline but r ...
is an
essential nutrient and its primary function within the human body is the synthesis of
cellular membranes,
although it serves other functions as well. It is a precursor molecule to the
neurotransmitter Acetylcholine which serves a wide range of functions including motor control and memory. Choline deficiencies may be related to some liver and
neurological disorders.
Because of its role in cellular synthesis, choline is an important nutrient during the prenatal and early postnatal development of offspring as it contributes to brain development.
[ Choline intakes from food for men, women and children may be below the ]Adequate Intake
The Dietary Reference Intake (DRI) is a system of nutrition recommendations from the National Academy of Medicine (NAM) of the National Academies (United States). It was introduced in 1997 in order to broaden the existing guidelines known as Reco ...
levels. Women, especially when pregnant or lactating, the elderly, and infants, are at risk for choline deficiency. Beef liver, wheat germ
Cereal germ or Wheat germ:
The germ of a cereal is the reproductive part that germinates to grow into a plant; it is the embryo of the seed. Along with bran, germ is often a by-product of the milling that produces refined grain products ...
, and egg yolks are common foods providing choline.[
]
Lutein and Zeaxanthin
Lutein and zeaxanthin are carotenoids that contain very strong antioxidants. Most of the research thus far has focused on the effect that these carotenoids have on vision and increased processing speeds of the eye. In recent years, scientists have shifted their focus to their contribution to brain development and cognition due to newly found bio-accumulation of lutein and zeaxanthin in the brain. These nutrients can be found mostly in dark, leafy greens. Some other foods include eggs, broccoli, zucchini, corn, and brussels sprouts. These foods should be raw or steamed in order to get the most nutrients out of them.
Omega 3 fatty acids
Omega 3 fatty acids are essential for brain development and support cognition. These acids affect how the cell receptors react inside of the cell membranes. The human body is not able to make, or synthesize, omega 3 or DHA acids on its own. This means that the only source we have for these vital fatty acids comes directly form the food that we eat. Many studies have shown that people who consume larger amounts of fish in their diet are less likely to suffer from depression. Fish, especially salmon, have large amounts of omega 3 fatty acids and docosahexaonic acid (DHA). In the last 100 years, the western civilizations have shown a significant decrease in DHA and omega 3 intake, and increase in saturated and trans fats. Comparatively, locations like the United States and Germany have dramatically more cases of major depression than locations like Japan, where their main food source comes from their fishing industry.
Foods for healthy brain development in children
There are many foods that support healthy brain development. Many experts recommend fitting some of the following foods into your everyday diet:
Salmon
Salmon is very high in omega 3 acids and DHA. There are other lean "white" fish meats, like albacore white tuna, that are a good source of protein but because they are more lean they are not high in fats. Salmon salad sandwiches, instead of tuna salad, will provide both protein and omega 3 fatty acids.
Flax Seeds
Aside from many other nutrients contained in flax seeds, just one tablespoon of flax seeds contains 1,597 mg of omega 3 fatty acids.
Blueberries and Strawberries
Many dark, rich colored berries are shown to improve memory.
Peanuts/Nuts/Seeds
Peanuts are a very good source of vitamin E which is an antioxidant. They also contains thiamin that helps support the brain and nervous systems. Nuts are also a very good source of protein for providing energy and increased concentration.
Whole Grains and Lean Beef
Whole grains provide a lot of glucose and fiber. The fiber from the grains helps to regulate the release of glucose into the body. Glucose sugars are used by your body for energy. Higher levels of energy are shown to improve concentration levels of the brain. Lean beef is an excellent source of iron which is also shown to provide energy levels and increase concentration. a
Colorful Veggies
These types of foods are rich with antioxidants needed to cleanse the blood stream and help to keep brain cells strong.
Milk/Yogurt/Dairy
Dairy foods provide the body with Vitamins B and D. Vitamin B is essential for brain tissue growth and also provides the body with enzymes.
Greens
Leafy greens such as collard greens, spinach, cabbage, romaine lettuce, and kale are a good source of folate and very rich in vitamins.
B-Vitamin deficiencies and cognition
B vitamins
B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. Though these vitamins share similar names (B1, B2, B3, etc.), they are chemically distinct compounds that often coexi ...
, also known as the B-complex, are an interrelated group of nutrients which often co-occur in food. The complex consists of: thiamine
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 ...
(B1), riboflavin (B2), niacin
Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
(B3), pantothenic acid
Pantothenic acid, also called vitamin B5 is a water-soluble B vitamin and therefore an essential nutrient. All animals require pantothenic acid in order to synthesize coenzyme A (CoA) – essential for fatty acid metabolism – as well as to, ...
(B5), pyridoxin (B6), folic acid
Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
(B9), cobalamin
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. ...
(B12), and biotin. B vitamins are not synthesized in the body, and thus need to be obtained from food. B-complex vitamins are water-soluble vitamins, which means that they are not stored within the body. In consequence, the B vitamins need ongoing replenishment.[ It is possible to identify broad cognitive effects of certain B vitamins, as they are involved in many significant metabolic processes within the brain.]
In a study done by a group of researchers in 2012, vitamin levels were measured in the subjects' blood and compared to the results from memory tests that they were given. The study showed that people with higher vitamin levels, mainly Vitamin B, had higher scores on their memory tests. The study was conducted at the Oregon Health & Science University and although it may still need official confirmation, there is sufficient evidence to support the fact that improving your diet can significantly increase the sharpness of your brain.
Vitamin B1 (thiamine)
This vitamin is important for the facilitation of glucose use, thus ensuring the production of energy for the brain, and normal functioning of the nervous system, muscles and heart. Thiamine is found throughout mammalian nervous tissue, including the brain and spinal cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...
. Metabolism and coenzyme function of the vitamin suggest a distinctive function for thiamine within the nervous system
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...
. The brain retains its thiamine content in the face of a vitamin-deficient diet with great tenacity, as it is the last of all nervous tissues studied to become depleted.
Lack of thiamin causes the disease known as beriberi
Thiamine deficiency is a medical condition of low levels of thiamine (Vitamin B1). A severe and chronic form is known as beriberi. The two main types in adults are wet beriberi and dry beriberi. Wet beriberi affects the cardiovascular system, ...
. There are two forms of beriberi
Thiamine deficiency is a medical condition of low levels of thiamine (Vitamin B1). A severe and chronic form is known as beriberi. The two main types in adults are wet beriberi and dry beriberi. Wet beriberi affects the cardiovascular system, ...
: "wet", and "dry". Dry beriberi is also known as cerebral beriberi and characterized by peripheral neuropathy
Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...
. Thiamine deficiency has been reported in up to 80% of people who are alcoholic due to inadequate nutritional intake, reduced absorption, and impaired utilization of thiamine. Clinical signs of B1 deficiency include mental changes such as apathy, decrease in short-term memory, confusion, and irritability; also increased rates of depression, 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 ...
, falls, and fractures in old age.
The lingering symptoms of neuropathy associated with cerebral beriberi are known as Korsakoff's syndrome, or the chronic phase of Wernicke-Korsakoff's. Wernicke encephalopathy is characterized by ocular abnormalities, ataxia of gait, a global state of confusion, and neuropathy. The state of confusion associated with Wernicke's may consist of apathy, inattention, spatial disorientation, inability to concentrate, and mental sluggishness or restlessness. Clinical diagnosis of Wernicke's disease cannot be made without evidence of ocular disturbance, yet these criteria may be too rigid. Korsakoff's syndrome likely represents a variation in the clinical manifestation of Wernicke encephalopathy, as they both share similar pathological origin. It is often characterized by confabulation
In psychology, confabulation is a memory error defined as the production of fabricated, distorted, or misinterpreted memories about oneself or the world. It is generally associated with certain types of brain damage (especially aneurysm in the an ...
, disorientation, and profound amnesia. Characteristics of the neuropathology are varied, but generally consist of bilaterally symmetrical midline lesion
A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals.
Types
There is no designated classif ...
s of brainstem areas, including the mammillary bodies
The mammillary bodies are a pair of small round bodies, located on the undersurface of the brain that, as part of the diencephalon, form part of the limbic system. They are located at the ends of the anterior arches of the fornix. They consist o ...
, thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
, periaqueductal region, 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 the cerebellar vermis
The cerebellar vermis (from Latin ''vermis,'' "worm") is located in the medial, cortico-nuclear zone of the cerebellum, which is in the posterior fossa of the cranium. The primary fissure in the vermis curves ventrolaterally to the superior su ...
. Immediate treatment of Wernicke encephalopathy involves the administration of intravenous thiamine, followed with long-term treatment and prevention of the disorder through oral thiamine supplements, alcohol abstinence, and a balanced diet. Improvements in brain functioning of chronic alcoholics may occur with abstinence-related treatment, involving the discontinuation of alcohol consumption and improved nutrition.
Vitamin B3 (niacin)
Vitamin B3, also known as niacin, includes both nicotinamide
Niacinamide or Nicotinamide (NAM) is a form of vitamin B3 found in food and used as a dietary supplement and medication. As a supplement, it is used by mouth to prevent and treat pellagra (niacin deficiency). While nicotinic acid (niacin) may ...
as well as nicotinic acid, both of which function in many biological oxidization and reduction reactions within the body. Niacin is involved in the synthesis of fatty acids
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an B ...
and 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 ...
, known mediators of brain biochemistry, and in effect, of cognitive function. Pellagra
Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over t ...
is a niacin deficiency disease. Pellagra is classically characterized by four 4 "D's": diarrhea, dermatitis
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can ...
, dementia, and death. Neuropsychiatric manifestations of pellagra include headache, irritability, poor concentration, anxiety, hallucinations, stupor, apathy, psychomotor unrest, photophobia, tremor, ataxia, spastic paresis, fatigue, and depression. Symptoms of fatigue and insomnia may progress to encephalopathy characterized by confusion, memory loss, and psychosis. Those afflicted with pellagra may undergo pathological alterations in the nervous system. Findings may include demylenation and degeneration of various affected parts of the brain, spinal cord, and peripheral nerves
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system.
A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the e ...
.
Oral nicotinamide has been promoted as an over-the-counter drug for the treatment of Alzheimer's dementia
Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As t ...
. Conversely, no clinically significant effect has been found for the drug, as nicotinamide administration has not been found to promote memory functions in people with mild to moderate dementia of either Alzheimers', vascular, or fronto-temporal types. This evidence suggests that nicotinamide may treat dementia as related to pellagra, but administration does not effectively treat other types of dementia. Though treatment with niacin does little to alter the effects of Alzheimer's dementia, niacin intake from foods is inversely associated with the disease.
Vitamin B9 (folic acid)
Folate and vitamin B12 play a vital role in the synthesis of S-adenosylmethionine, which is of key importance in the maintenance and repair of all cells, including neurons. In addition, folate has been linked to the maintenance of adequate brain levels of cofactors necessary for chemicals reactions that lead to the synthesis of serotonin and catecholamine neurotransmitters. Concentrations of blood plasma folate and homocysteine
Homocysteine is a non-proteinogenic α-amino acid. It is a homologue of the amino acid cysteine, differing by an additional methylene bridge (-CH2-). It is biosynthesized from methionine by the removal of its terminal Cε methyl group. In th ...
concentrations are inversely related, such that an increase in dietary folate decreases homocysteine concentration. Thus, dietary intake of folate is a major determinant of homocysteine levels within the body. The relationship between folate and B12 is so interdependent that deficiency in either vitamin can result in megaloblastic anemia
Megaloblastic anemia is a type of macrocytic anemia. An anemia is a red blood cell defect that can lead to an undersupply of oxygen. Megaloblastic anemia results from inhibition of DNA synthesis during red blood cell production. When DNA synth ...
, characterized by organic mental change.
The link between levels of folate and altered mental function is not large, but is sufficient enough to suggest a causal association. Deficiency in folate can cause an elevation of homocysteine within the blood, as the clearance of homocysteine requires enzymatic action dependent on folate, and to a lesser extent, vitamins B6 and B12. Elevated homocysteine has been associated with increased risk of vascular events, as well as dementia.
Differences lie in the presentation of megaloblastic anemia induced by either folate or B12 deficiency. Megaloblastic anemia related to deficiency in B12 generally results in peripheral neuropathy, whereas folate-related anemia often results in affective, or mood disorders. Neurological effects are not often associated with folate-related megaloblastic anemia, although demyelinating disorders may eventually present. In one study, mood disturbances were recorded for the majority of people with megaloblastic anemia in the absence of B12 deficiency. In addition, folate concentrations within blood plasma have been found to be lower in people with both unipolar and bipolar depressive disorders when compared with control groups. In addition, depressive groups with low folate concentrations responded less well to standard antidepressant therapy than did those with normal levels within plasma. However, replication of these findings are less robust.
Intake of the vitamin has been linked to deficits in learning and memory, particularly within the elderly population. Elderly people deficient in folate may present with deficits in free recall and recognition, which suggests that levels of folate may be related to efficacy of episodic memory. Lack of adequate folate may produce a form of dementia considered to be reversible with administration of the vitamin. Indeed, there is a degree of improvement in memory associated with folate treatment. In a 3-year longitudinal study of men and women aged 50–70 years with elevated homocysteine plasma concentration, researchers found that a daily oral folic acid supplementation of 800μg resulted in an increase in folate levels and a decrease in homocysteine levels within blood plasma. In addition to these results, improvements of memory, and information-processing speed, as well as slight improvements of sensorimotor speed were observed, which suggests there is a link between homocysteine and cognitive performance. However, while the amount of cognitive improvement after treatment with folate is correlated with the severity of folate deficiency, the severity of cognitive decline is independent of the severity of folate deficiency. This suggests that the dementia observed may not be entirely related to levels folate, as there could be additional factors that were not accounted for which might have an effect.
Because neurulation may be completed before pregnancy is recognized, it is recommended that women capable of becoming pregnant take about 400μg of folic acid from fortified foods, supplements, or a combination of the two in order to reduce the risk of neural tube defects. These major anomalies in the nervous system can be reduced by 85% with systematic folate supplementation occurring before the onset of pregnancy. The incidence of Alzheimer's and other cognitive diseases has been loosely connected to deficiencies in folate. It is recommended for the elderly to consume folate through food, fortified or not, and supplements in order to reduce risk of developing the disease.
Additionally, folic acid
Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
has also been found to improve the memory of older people. There is some evidence that deficiency in folic acid may increase the risk of dementia, especially Alzheimer's disease and vascular dementia, but there is debate about whether it lowers risk of cognitive impairment in the older population. Folic acid supplementation is shown to lower blood homocysteine levels, while folic acid deficiency can lead to a condition of high levels of homocysteine (Hcy) in the bloodstream called hyperhomocysteinemia
Hyperhomocysteinemia is a medical condition characterized by an abnormally high level of homocysteine in the blood, conventionally described as above 15 μmol/L.
As a consequence of the biochemical reactions in which homocysteine is involved ...
(HHcy). HHcy is related to several vascular diseases such as coronary artery disease, peripheral vascular disease, and stroke.
Vitamin B12 (cobalamin)
Also known as cobalamin, B12 is important for the maintenance of neurological function and psychiatric health. B12 deficiency, also known as hypocobalaminemia, often results from complications involving absorption into the body. An assortment of neurological effects can be observed in 75–90% of individuals of any age with clinically observable B12 deficiency. Cobalamin deficiency manifestations are apparent in the abnormalities of the spinal cord, peripheral nerves, optic nerves, and cerebrum
The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb ...
. These abnormalities involve a progressive degeneration of myelin
Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be ...
, and may be expressed behaviorally through reports of sensory disturbances in the extremities, or motor disturbances, such as gait ataxia. Combined myelopathy and neuropathy are prevalent within a large percentage of cases. Cognitive changes may range from loss of concentration to memory loss, disorientation, and dementia. All of these symptoms may present with or without additional mood changes. Mental symptoms are extremely variable, and include mild disorders of mood, mental slowness, and memory defect. Memory defect encompasses symptoms of confusion
In medicine, confusion is the quality or state of being bewildered or unclear. The term "acute mental confusion" , severe agitation and depression, delusions and paranoid behavior, visual and auditory hallucinations, dysphasia, violent maniacal behavior and epilepsy. It has been suggested that mental symptoms could be related to a decrease in cerebral metabolism, as caused by the state of deficiency.
Mild to moderate cases of pernicious anemia may show poor concentration
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', '' number concentration'', ...
. In severe cases of pernicious anemia, individuals may present with various cognitive problems such as dementia, and memory loss. It is not always easy to determine whether B12 deficiency is present, especially within older adults. People may present with violent behavior or more subtle personality changes. They may also present with vague complaints, such as fatigue or memory loss, that may be attributed to normative aging processes. Cognitive symptoms may mimic behavior in Alzheimer's and other dementias as well.
People who are deficient in B12 despite normal absorption functionality may be treated through oral administration of at least 6 µg/day of the vitamin in pill form. People who suffer from irreversible causes of deficiency, such as pernicious anemia or old age, will need lifelong treatment with pharmacological doses of B12. Strategy for treatment is dependent on the person's level of deficiency as well as their level of cognitive functioning. Treatment for those with severe deficiency involves 1000 µg of B12 administered intramuscularly
Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles have ...
daily for one week, weekly for one month, then monthly for the rest of the person's life. The progression of neurological manifestations of cobalamin deficiency is generally gradual. As a result, early diagnosis is important or else irreversible damage may occur. People who become demented usually show little to no cognitive improvement with the administration of B12. There is risk that folic acid administered to those with B12 deficiency may mask anemic symptoms without solving the issue at hand. In this case, people would still be at risk for neurological deficits associated with B12 deficiency-related anemia, which are not associated with anemia related to folate deficiency.
Vitamin A deficiency and impaired memory
Vitamin A
Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably ...
is an essential nutrient for mammals which takes form in either retinol
Retinol, also called vitamin A1, is a fat-soluble vitamin in the vitamin A family found in food and used as a dietary supplement. As a supplement it is used to treat and prevent vitamin A deficiency, especially that which results in xeroph ...
or the provitamin A provitamin is a substance that may be converted within the body to a vitamin. The term previtamin is a synonym.
The term "provitamin" is used when it is desirable to label a substance with little or no vitamin activity, but which can be converted ...
beta-Carotene. It helps regulation of cell division, cell function, genetic regulation, helps enhance the immune system, and is required for brain function, chemical balance, growth and development of the central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
and vision.
Iron deficiency and cognition
Oxygen transportation, DNA synthesis, myelin synthesis, oxidative phosphorylation, and neurotransmitter synthesis and metabolism are all biological processes that require iron; however, an iron imbalance can result in neurotoxicity causing oxidation and modification of lipids, proteins, carbohydrates, and DNA. Hypoxic conditions in severely anemic individuals may cause brain damage resulting in cognitive impairment. When iron levels in the brain are disrupted neurophysiological mechanisms and cognition are affected, potentially resulting in long-term behavioral changes and may affect attention span, intelligence, sensory perception functions, mood, and behavior. Neuropathies such as ADHD, autism, depression, anxiety, schizophrenia, and bipolar disorder are seen in iron deficient individuals. However, excessive iron accumulation can be seen in neurodegenerative diseases including Alzheimer’s and Huntington’s disease. Iron is needed to develop the central nervous system (CNS), endocrine system, autoimmune system, and brain. Iron is involved with the development and functioning of different neurotransmitter systems and large iron quantities are required for the myelination of white brain matter. Abnormal myelination of white matter due to iron deficiency during development may be related to the onset of psychological disorders in adolescents. Decreased iron concentration results in a reduction of neurotransmitter levels, in turn leading to poor myelination and delayed neuromaturation.
Aging and cognitive disease
Foods that are rich in omega-3 fatty acids have been shown to decrease risk of getting Alzheimer's disease.
Omega-3 fatty acids
Omega-3 fatty acids, primarily docosahexaenoic acid
Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. In physiological literature, it is given the name 22:6(n-3). It can be synthesized from alpha-lin ...
(DHA), which is the most prevalent omega-3 fatty acid found in neurons, have been studied extensively for use in possible prevention and therapy of Alzheimer's disease. Some studies (cross-sectional) suggest that reduced intake or low brain levels of DHA are associated with earlier development of cognitive deficits or development of dementia, including Alzheimer's disease. Several clinical trials suggest that omega-3 fatty acid supplementation does not have significant effects in the treatment of Alzheimer's disease—which in turn may suggest that the protective benefits of omega-3 fatty acid supplementation could depend on the scope of the disease and other confounding factors. A diet that is rich in antioxidants will also help get rid of free radicals in the body, which could be a cause for Alzheimer's. The buildup of Beta Amyloid plaques, a marker highly associated with Alzheimer's disease, generates cell damaging free radicals. Therefore, the role of antioxidants as protectants against Alzheimer's disease has become a hot topic of study. Simple dietary modification, towards fewer highly processed carbohydrates and relatively more fats ad cholesterol, is likely a protective measure against Alzheimer's disease.
See also
*Nootropic
Nootropics ( , or ) (colloquial: smart drugs and cognitive enhancers, similar to adaptogens) are a wide range of natural or synthetic dietary supplement, supplements or drugs and other substances that are claimed to improve cognitive function ...
*Nutrition
Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient ...
* Nutritional neuroscience
*Pellagra
Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over t ...
*Wernicke–Korsakoff syndrome
Wernicke–Korsakoff syndrome (WKS) is the combined presence of Wernicke encephalopathy (WE) and Korsakoff syndrome. Due to the close relationship between these two disorders, people with either are usually diagnosed with WKS as a single syndrome ...
References
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Nutrition
Cognition
Memory