Central nervous system fatigue, or central fatigue, is a form of
fatigue
Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...
that is associated with changes in the
synaptic concentration of
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 ...
s within 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 par ...
(CNS; including 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 v ...
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 spi ...
) which affects exercise performance and muscle function and cannot be explained by peripheral factors that affect muscle function.
In healthy individuals, central fatigue can occur from prolonged
exercise
Exercise is a body activity that enhances or maintains physical fitness and overall health and wellness.
It is performed for various reasons, to aid growth and improve strength, develop muscles and the cardiovascular system, hone athletic ...
and is associated with neurochemical changes in the brain, primarily involving
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 ...
(5-HT),
noradrenaline
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
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 ...
.
Central fatigue plays an important role in endurance sports and also highlights the importance of proper nutrition in endurance athletes.
Neurochemical mechanisms
Existing experimental methods have provided enough evidence to suggest that variations in synaptic
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 ...
,
noradrenaline
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
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 ...
are significant drivers of
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 par ...
fatigue.
An increased synaptic dopamine concentration in the CNS is strongly
ergogenic
Performance-enhancing substances, also known as performance-enhancing drugs (PEDs), are substances that are used to improve any form of activity performance in humans. A well-known example of cheating in sports involves doping in sport, where ba ...
(promotes exercise performance).
An increased synaptic serotonin or noradrenaline concentration in the CNS impairs exercise performance.
Noradrenaline
Manipulation of norepinephrine suggests it may actually play a role in creating a feeling of fatigue. Reboxetine, an NRI, decreased time to fatigue and increased subjective feelings of fatigue.
This may be explained by a paradoxical decrease in adrenergic activity led by feedback mechanisms.
Serotonin
In the brain, serotonin is a
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 ...
and regulates
arousal
Arousal is the physiological and psychological state of being awoken or of sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the brain, which mediates wakefulness, th ...
,
behavior
Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as wel ...
,
sleep
Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a de ...
, and
mood, among other things.
[Young, S. N. The clinical psychopharmacology of tryptophan. In: Nutrition and the Brain. Vol. 7, R. J. Wurtman and J. J. Wurtman, (Eds.). New York: Raven, 1986, pp. 49–88] During prolonged exercise where central nervous system fatigue is present, serotonin levels in the brain are higher than normal physiological conditions; these higher levels can increase perceptions of effort and peripheral muscle fatigue.
The increased synthesis of brain serotonin occurs because of a higher proportion of
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 ...
, the serotonin precursor, in the blood and which results in larger amounts of tryptophan crossing the blood–brain barrier. An important factor of serotonin synthesis is the transport mechanism of tryptophan across the
blood–brain barrier
The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that prevents solutes in the circulating blood from ''non-selectively'' crossing into the extracellular fluid of ...
. The transport mechanism for tryptophan is shared with the
branched chain amino acids
A branched-chain amino acid (BCAA) is an amino acid having an aliphatic side-chain with a branch (a central carbon atom bound to three or more carbon atoms). Among the proteinogenic amino acids, there are three BCAAs: leucine, isoleucine, and v ...
(BCAAs),
leucine
Leucine (symbol Leu or L) is an essential amino acid that is used in the biosynthesis of proteins. Leucine is an α-amino acid, meaning it contains an α-amino group (which is in the protonated −NH3+ form under biological conditions), an α- ca ...
,
isoleucine
Isoleucine (symbol Ile or I) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), an α-carboxylic acid group (which is in the deprot ...
, and
valine
Valine (symbol Val or V) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH3+ form under biological conditions), an α- carboxylic acid group (which is in the deprotonat ...
. During extended exercise, BCAAs are consumed for skeletal muscle contraction, allowing for greater transport of tryptophan across the blood–brain barrier. None of the components of the serotonin synthesis reaction are saturated under normal physiological conditions, allowing for the increased production of the neurotransmitter. However the failure of BCAAs to decrease time to fatigue consistently limit this hypothesis. This may be due to a counter-acting mechanism: BCAAs also limit the uptake of
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 Gr ...
, another aromatic amino acid, like tryptophan. Tyrosine is a precursor to
catecholamine
A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine.
Catechol can be either a free molecule or a subst ...
, which enhances performance drive.
Dopamine
Dopamine is a neurotransmitter that regulates arousal,
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 ...
, muscular coordination, and endurance performance, among other things. Dopamine levels have been found to be lower after prolonged exercise. A decrease in dopamine can decrease athletic performance as well as mental motivation. Dopamine itself cannot cross the blood brain barrier and must be synthesized within the brain. In rats bred for running, increased activity of the
ventral tegmental area
The ventral tegmental area (VTA) (tegmentum is Latin for ''covering''), also known as the ventral tegmental area of Tsai, or simply ventral tegmentum, is a group of neurons located close to the midline on the floor of the midbrain. The VTA is the ...
have been observed, and VTA activity correlates with voluntary wheel running. As the VTA is an area dense in dopaminergic neurons that project to many areas of the brain, this suggests that dopaminergic neurotransmission drives physical performance. Further supporting this theory is the fact that dopamine reuptake inhibitors as well as norepinephrine dopamine reuptake inhibitors are able to increase exercise performance, especially in the heat.
Acetylcholine
Acetylcholine
Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Part ...
is required for the generation of muscular force. In the central nervous system, acetylcholine modulates arousal and temperature regulation. It also may play a role in central fatigue. During exercise, levels of acetylcholine drop.
[Conlay, L. A., Sabournjian, L. A., and Wurtman, R. J. Exercise and neuromodulators: choline and acetylcholine in marathon runners.Int. J. Sports Med. 13(Suppl. 1):S141-142, 1992] This is due to a decrease in plasma choline levels. However, there have been conflicting results in studies about the effect of acetylcholine on fatigue. One study found that plasma choline levels had dropped 40% after the subjects ran the Boston Marathon.
Another study found that choline supplementation did not improve time to exhaustion. This study also found that plasma choline levels had not changed in either the placebo or the choline supplemented groups. More research is needed to investigate acetylcholine's effects on fatigue.
Cytokines
Cytokines can manipulate neurotransmissions creating
sickness behavior
350px, Ancher, Michael, "The Sick Girl", 1882, Statens Museum for Kunst
Sickness behavior is a coordinated set of adaptive behavioral changes that develop in ill individuals during the course of an infection.
They usually, but not always, acco ...
, characterized by malaise and fatigue. In animal models,
IL-1b
Interleukin-1 beta (IL-1β) also known as leukocytic pyrogen, leukocytic endogenous mediator, mononuclear cell factor, lymphocyte activating factor and other names, is a cytokine protein that in humans is encoded by the ''IL1B'' gene."Catabolin" ...
stimulates serotonin release and increases activity of GABA.
Lipopolysaccharide
Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by a covalent bond, and are found in the outer m ...
challenges also inhibit activity of histaminergic and dopaminergic neurons.
Ammonia
Increased circulating levels of ammonia may alter brain function and result in fatigue. One hypothesized reason that BCAAs fail to increase exercise performance is due to increased oxidation of BCAAs in supplementation that results in increased fatigue, canceling out the effects on serotonin receptors.
Manipulation
Controlling central nervous system fatigue can help scientists develop a deeper understanding of
fatigue
Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...
as a whole. Numerous approaches have been taken to manipulate neurochemical levels and behavior. In sports, nutrition plays a large role in athletic performance. In addition to fuel, many athletes consume
performance-enhancing drugs
Performance-enhancing substances, also known as performance-enhancing drugs (PEDs), are substances that are used to improve any form of activity performance in humans. A well-known example of cheating in sports involves doping in sport, where bann ...
including stimulants in order to boost their abilities.
Dopamine reuptake and release agents
Amphetamine
Amphetamine (contracted from alpha- methylphenethylamine) is a strong central nervous system (CNS) stimulant that is used in the treatment of attention deficit hyperactivity disorder (ADHD), narcolepsy, and obesity. It is also commonly used ...
is a stimulant that has been found to improve both physical and cognitive performance. Amphetamine blocks the reuptake of dopamine and norepinephrine, which delays the onset of fatigue by increasing the amount of dopamine, despite the concurrent increase in norepinephrine, in the central nervous system.
Amphetamine is a widely used substance among collegiate athletes for its performance enhancing qualities, as it can improve muscle strength, reaction time, acceleration,
anaerobic exercise
Anaerobic exercise is a type of exercise that breaks down glucose in the body without using oxygen; ''anaerobic'' means "without oxygen". In practical terms, this means that anaerobic exercise is more intense, but shorter in duration than aerobi ...
performance, power output at fixed levels of
perceived exertion, and
endurance
Endurance (also related to sufferance, resilience, constitution, fortitude, and hardiness) is the ability of an organism to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from a ...
.
Methylphenidate has also been shown to increase exercise performance in time to fatigue and time trial studies.
Caffeine
Caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...
is the most widely consumed stimulant in North America. Caffeine causes the release of epinephrine from the adrenal medulla. In small doses, caffeine can improve endurance. It has also been shown to delay the onset of fatigue in exercise. The most probable mechanism for the delay of fatigue is through the obstruction of
adenosine
Adenosine ( symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9-glycosidic bond. Adenosine is one of the four nucleoside building ...
receptors in the central nervous system. Adenosine is a neurotransmitter that decreases arousal and increases sleepiness. By preventing adenosine from acting, caffeine removes a factor that promotes rest, and delays fatigue.
Carbohydrates
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 ...
are the main source of energy in organisms for
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
. They are an important source of fuel in exercise. A study conducted by the Institute of Food, Nutrition, and Human Health at Massey University investigated the effect of consuming a
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 ma ...
and
electrolyte
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 dis ...
solution on muscle
glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.
Glycogen functions as one o ...
use and running capacity on subjects that were on a high carbohydrate diet. The group that consumed the carbohydrate and electrolyte solution before and during exercise experienced greater endurance capacity. This could not be explained by the varying levels of muscle glycogen; however, higher
plasma glucose
Glycaemia, also known as blood sugar level, blood sugar concentration, or blood glucose level is the measure of glucose concentrated in the blood of humans or other animals. Approximately 4 grams of glucose, a simple sugar, is present in the bl ...
concentration may have led to this result. Dr. Stephen Bailey posits that the central nervous system can sense the influx of carbohydrates and reduces the perceived effort of the exercise, allowing for greater endurance capacity.
Branched-chain amino acids
Several studies have attempted to decrease the synthesis of serotonin by administering
branched-chain amino acid
A branched-chain amino acid (BCAA) is an amino acid having an aliphatic side-chain with a branch (a central carbon atom bound to three or more carbon atoms). Among the proteinogenic amino acids, there are three BCAAs: leucine, isoleucine, and ...
s and inhibiting the transport of tryptophan across the blood brain barrier. The studies performed resulted in little or no change in performance between increased BCAA intake and placebo groups. One study in particular administered a carbohydrate solution and a carbohydrate + BCAA solution. Both of the groups were able to run for longer before fatigue compared to the water placebo group. However, both the carbohydrate and the carbohydrate + BCAA groups had no differences in their performance. Branch-chained amino acid supplementation has proven to have little to no effect on performance. There has been little success utilizing neurotransmitter precursors to control central nervous system fatigue.
One review hypothesized that the inconsistency with BCAA administration was the result of ammonia accumulation as a result of increased BCAA oxidation.
Role
Central nervous system fatigue is a key component in preventing peripheral muscle injury. The brain has numerous receptors, such as
osmoreceptors
An osmoreceptor is a sensory receptor primarily found in the hypothalamus of most homeothermic organisms that detects changes in osmotic pressure. Osmoreceptors can be found in several structures, including two of the circumventricular organs – t ...
, to track
dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
,
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 n ...
, and
body temperature
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
. With that information as well as peripheral muscle fatigue information, the brain can reduce the quantity of motor commands sent from the central nervous system. This is crucial in order to protect the
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 ...
of the body and to keep it in a proper physiological state capable of full recovery. The reduction of motor commands sent from the brain increases the amount of perceived effort an individual experiences. By forcing the body through a higher perceived intensity, the individual becomes more likely to cease exercise by means of exhaustion. Perceived effort is greatly influenced by the intensity of corollary discharge from the
motor cortex
The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements.
The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately a ...
that affects the
primary somatosensory cortex
In neuroanatomy, the primary somatosensory cortex is located in the postcentral gyrus of the brain's parietal lobe, and is part of the somatosensory system. It was initially defined from surface stimulation studies of Wilder Penfield, and paralle ...
. Endurance athletes learn to listen to their body. Protecting organs from potentially dangerous core temperatures and nutritional lows is an important brain function. Central nervous system fatigue alerts the athlete when physiological conditions are not optimal so either rest or refueling can occur. It is important to avoid
hyperthermia
Hyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme ...
and
dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
, as they are detrimental to athletic performance and can be fatal.
Possible connection with Chronic fatigue syndrome
Chronic fatigue syndrome
Chronic fatigue syndrome (CFS), also called myalgic encephalomyelitis (ME) or ME/CFS, is a complex, debilitating, long-term medical condition. The causes and mechanisms of the disease are not fully understood. Distinguishing core symptoms are ...
is a name for a group of diseases that are dominated by persistent fatigue. The fatigue is not due to exercise and is not relieved by rest.
Through numerous studies, it has been shown that people with chronic fatigue syndrome have an integral central fatigue component.
In one study, the subjects' skeletal muscles were checked to ensure they had no defects that prevented their total use. It was found that the muscles functioned normally on a local level, but they failed to function to their full extent as a whole. The subjects were unable to consistently activate their muscles during sustained use, despite having normal muscle tissue. In another study, the subjects experienced higher perceived effort in relation to heart rate as compared to the control during a graded exercise test. The chronic fatigue subjects would stop before any sort of limit on the body was reached. Both studies proved that peripheral muscle fatigue was not causing the subjects with chronic fatigue syndrome to cease exercising. It is possible that the higher perception of effort required to use the muscles results in great difficulty in accomplishing consistent exercise.
The main cause of fatigue in chronic fatigue syndrome most likely lies in the central nervous system. A defect in one of its components could cause a greater requirement of input to result in sustained force. It has been shown that with very high motivation, subjects with chronic fatigue can exert force effectively. Further investigation into central nervous system fatigue may result in medical applications.
Loud Noise Exposure Damage
Exposure to
loud noise is a major environmental threat to public
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 ...
. Loud noise exposure, apart from affecting the
inner ear
The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...
, is deleterious for
cardiovascular
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
,
endocrine and
nervous systems
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 th ...
and it is associated with
neuropsychiatric disorders
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 ...
. A study indicates that loud noise exposure represents a detrimental stimulus for specific brain areas. This consists mostly on decreased
catecholamine
A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine.
Catechol can be either a free molecule or a subst ...
innervation which involves multiple brain regions. These data lend substance to clinical findings showing impaired memory, mood alterations and other behavioral alterations induced by prolonged noise exposure. The occurrence of
nigrostriatal dopamine innervation further strengthens this association. Similarly, in
Parkinson’s disease
Parkinson's disease (PD), or simply Parkinson's, is a chronic condition, long-term neurodegeneration, degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disea ...
a loss of auditory function occurs, which is compatible with the loss of cochlear
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 ...
innervation, which in turn protects from the effects of loud noise. Thus, a vicious circle may occur, where the
excitotoxic
In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate re ...
effects of loud noise may destroy dopamine nerve endings producing a loss of dopamine in their terminal fields, including the efferent synapses with cochlear hair cells, where dopamine exerts a gating control. In this way, the transmission of loud noise would no longer be hampered despite a loss in the detection of pure tones. Altogether the findings provide a bridge between environmental exposure to loud noise and the onset of neuropsychiatric alterations such as:
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 ...
,
depressive symptoms
Depression is a mental state of low Mood (psychology), 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 disorder, mental and Abnor ...
,
behavioral abnormalities,
movement disorders
Movement disorder refers to any clinical syndrome with either an excess of movement or a paucity of voluntary and involuntary movements, unrelated to weakness or spasticity. Movement disorders are synonymous with basal ganglia or extrapyramidal d ...
, as recently documented in general populations. Since environmental noise exposure represents an increasing worldwide polluting agent, loud noise exposure deserve particular attention in the light of their potential impact on public health.
References
{{Reflist
Central nervous system disorders
Exercise physiology