neurodegenerative disease
A neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic ...
linked to repeated trauma to the head. The
encephalopathy
Encephalopathy (; from grc, ἐνκέφαλος "brain" + πάθος "suffering") means any disorder or disease of the brain, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but r ...
symptoms can include behavioral problems, mood problems, and problems with thinking. The disease often gets worse over time and can result in
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 ...
. It is unclear if the risk of suicide is altered.
Most documented cases have occurred in athletes involved in striking-based
combat sports
A combat sport, or fighting sport, is a competitive contact sport that usually involves one-on-one combat. In many combat sports, a contestant wins by scoring more points than the opponent, submitting the opponent with a hold, disabling the opp ...
, such as
boxing
Boxing (also known as "Western boxing" or "pugilism") is a combat sport in which two people, usually wearing protective gloves and other protective equipment such as hand wraps and mouthguards, throw punches at each other for a predetermine ...
mixed martial arts
Mixed martial arts (MMA), sometimes referred to as cage fighting, no holds barred (NHB), and ultimate fighting, and originally referred to as Vale Tudo is a full-contact combat sport based on striking, grappling and ground fighting, inc ...
, and Muay Thai—hence its original name ''dementia pugilistica'' (
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
for "fistfighter's
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 ...
")—and
contact sports
Contact sports are sports that emphasize or require physical contact between players. Some sports, such as mixed martial arts, are scored on impacting an opponent, while others, including rugby football, gridiron football and Australian rules foot ...
such as
American football
American football (referred to simply as football in the United States and Canada), also known as gridiron, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team wi ...
professional wrestling
Professional wrestling is a form of theater that revolves around staged wrestling matches. The mock combat is performed in a ring similar to the kind used in boxing, and the dramatic aspects of pro wrestling may be performed both in the ring or ...
,
ice hockey
Ice hockey (or simply hockey) is a team sport played on ice skates, usually on an ice skating rink with lines and markings specific to the sport. It belongs to a family of sports called hockey. In ice hockey, two opposing teams use ice h ...
association football
Association football, more commonly known as football or soccer, is a team sport played between two teams of 11 players who primarily use their feet to propel the ball around a rectangular field called a pitch. The objective of the game is ...
baseball
Baseball is a bat-and-ball sport played between two teams of nine players each, taking turns batting and fielding. The game occurs over the course of several plays, with each play generally beginning when a player on the fielding t ...
and
basketball
Basketball is a team sport in which two teams, most commonly of five players each, opposing one another on a rectangular court, compete with the primary objective of shooting a basketball (approximately in diameter) through the defender's h ...
, and military
combat arms
Combat arms (or fighting arms in non-American parlance) are troops within national armed forces who participate in direct tactical ground combat. In general, they are units that carry or employ weapons, such as infantry, cavalry, and artillery ...
occupations. Other risk factors include being in the military, prior domestic violence, and repeated banging of the head. The exact amount of trauma required for the condition to occur is unknown, and as of 2022 definitive diagnosis can only occur at autopsy. The disease is classified as a
tauopathy
Tauopathy belongs to a class of neurodegenerative diseases involving the aggregation of tau protein into neurofibrillary or gliofibrillary tangles in the human brain. Tangles are formed by hyperphosphorylation of the microtubule protein known ...
.
There is no specific treatment for the disease. Rates of CTE have been found to be about 30% among those with a history of multiple head injuries; however, population rates are unclear. Research in brain damage as a result of repeated head injuries began in the 1920s, at which time the condition was known as ''dementia pugilistica'' or "fistfighter's dementia", "boxer's madness", or "punch drunk syndrome". It has been proposed that the rules of some sports be changed as a means of prevention.
Signs and symptoms
Symptoms of CTE, which occur in four stages, generally appear eight to ten years after an individual experiences repetitive mild traumatic brain injuries.
First-stage symptoms are
confusion
In medicine, confusion is the quality or state of being bewildered or unclear. The term "acute mental confusion"
dizziness
Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness.
Dizziness is a common medical c ...
, and headaches. Second-stage symptoms include
memory loss
Amnesia is a deficit in memory caused by brain damage or disease,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be caused temporarily by the use o ...
, social instability, impulsive behavior, and poor judgment. Third and fourth stages include progressive
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 ...
,
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 ...
speech impediments
Speech disorders or speech impairments are a type of communication disorder in which normal speech is disrupted. This can mean stuttering, lisps, etc. Someone who is unable to speak due to a speech disorder is considered mute. Speech skills are ...
,
sensory processing disorder
Sensory processing disorder (SPD, formerly known as sensory integration dysfunction) is a condition in which multisensory input is not adequately processed in order to provide appropriate responses to the demands of the environment. Sensory proces ...
vertigo
Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...
,
deafness
Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. In this context it is written ...
suicidality
Suicide is the act of intentionally causing one's own death. Mental disorders (including depression, bipolar disorder, schizophrenia, personality disorders, anxiety disorders), physical disorders (such as chronic fatigue syndrome), and subs ...
.
Additional symptoms include
dysarthria
Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectively ...
,
dysphagia
Dysphagia is difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right.
It may be a sensation that suggests difficulty in the passage of solids or liq ...
,
cognitive disorder
Cognitive disorders (CDs), also known as neurocognitive disorders (NCDs), are a category of mental health disorders that primarily affect cognitive abilities including learning, memory, perception, and problem solving. Neurocognitive disorders i ...
s such as amnesia, and ocular abnormalities, such as ptosis. The condition manifests as
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 ...
, or declining mental ability, problems with memory, dizzy spells or lack of balance to the point of not being able to walk under one's own power for a short time and/or
Parkinsonism
Parkinsonism is a clinical syndrome characterized by tremor, bradykinesia (slowed movements), rigidity, and postural instability. These are the four motor symptoms found in Parkinson's disease (PD), after which it is named, dementia with Lewy b ...
, or tremors and lack of coordination. It can also cause speech problems and an unsteady gait. Patients with CTE may be prone to inappropriate or explosive behavior and may display
pathological jealousy
Pathological jealousy, also known as morbid jealousy, Othello syndrome or delusional jealousy, is a psychological disorder in which a person is preoccupied with the thought that their spouse or sexual partner is being unfaithful without having a ...
or
paranoia
Paranoia is an instinct or thought process that is believed to be heavily influenced by anxiety or fear, often to the point of delusion and irrationality. Paranoid thinking typically includes persecutory beliefs, or beliefs of conspiracy co ...
.
Cause
Most documented cases have occurred in athletes with mild repetitive head impacts (RHI) over an extended period of time. Evidence indicates that repetitive concussive and subconcussive blows to the head cause CTE. Specifically
contact sports
Contact sports are sports that emphasize or require physical contact between players. Some sports, such as mixed martial arts, are scored on impacting an opponent, while others, including rugby football, gridiron football and Australian rules foot ...
such as
boxing
Boxing (also known as "Western boxing" or "pugilism") is a combat sport in which two people, usually wearing protective gloves and other protective equipment such as hand wraps and mouthguards, throw punches at each other for a predetermine ...
,
American football
American football (referred to simply as football in the United States and Canada), also known as gridiron, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team wi ...
wrestling
Wrestling is a series of combat sports involving grappling-type techniques such as clinch fighting, throws and takedowns, joint locks, pins and other grappling holds. Wrestling techniques have been incorporated into martial arts, combat ...
,
mixed martial arts
Mixed martial arts (MMA), sometimes referred to as cage fighting, no holds barred (NHB), and ultimate fighting, and originally referred to as Vale Tudo is a full-contact combat sport based on striking, grappling and ground fighting, inc ...
,
ice hockey
Ice hockey (or simply hockey) is a team sport played on ice skates, usually on an ice skating rink with lines and markings specific to the sport. It belongs to a family of sports called hockey. In ice hockey, two opposing teams use ice h ...
association football
Association football, more commonly known as football or soccer, is a team sport played between two teams of 11 players who primarily use their feet to propel the ball around a rectangular field called a pitch. The objective of the game is ...
. In association football (soccer), whether this is just associated with prolific headers or other injuries is unclear as of 2017. Other potential risk factors include military personnel (repeated exposure to explosive charges or large caliber ordnance), domestic violence, and repeated impact to the head. The exact amount of trauma required for the condition to occur is unknown although it is believed that it may take years to develop.
tauopathies
Tauopathy belongs to a class of neurodegenerative diseases involving the aggregation of tau protein into neurofibrillary or gliofibrillary tangles in the human brain. Tangles are formed by hyperphosphorylation of the microtubule protein known ...
, such as Alzheimer's disease. The four clinical stages of observable CTE disability have been correlated with tau pathology in brain tissue, ranging in severity from focal perivascular epicenters of neurofibrillary tangles in the frontal neocortex to severe tauopathy affecting widespread brain regions.
The primary physical manifestations of CTE include a reduction in brain weight, associated with atrophy of the frontal and temporal cortices and
medial temporal lobe
The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.
The temporal lobe is involved in pro ...
third ventricle
The third ventricle is one of the four connected ventricles of the ventricular system within the mammalian brain. It is a slit-like cavity formed in the diencephalon between the two thalami, in the midline between the right and left lateral ...
are often enlarged, with rare instances of dilation of the
fourth ventricle
The fourth ventricle is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the ventricular system, consist of the left and right lateral ventricles, the third ventricle, and the fourth ve ...
. Other physical manifestations of CTE include anterior cavum septi pellucidi and posterior
fenestra
A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical st ...
olfactory bulbs
The olfactory bulb (Latin: ''bulbus olfactorius'') is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex (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, ...
,
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 ...
, brainstem and cerebellum. As CTE progresses, there may be marked atrophy of the
hippocampus
The hippocampus (via Latin from Greek , ' seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, ...
,
entorhinal cortex
The entorhinal cortex (EC) is an area of the brain's allocortex, located in the medial temporal lobe, whose functions include being a widespread network hub for memory, navigation, and the perception of time.Integrating time from experience in the ...
, and
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 ...
.
On a microscopic scale, a pathognomonic CTE lesion involves p-tau aggregates in neurons, with or without thorn-shaped astrocytes, at the depths of the cortical sulcus around a small blood vessel, deep in the parenchyma, and not restricted to the subpial and superficial region of the sulcus; the pathognomonic lesion must include p-tau in neurons to distinguish CTE from ARTAG ( Aging-related tau astrogliopathy.) Supporting features of CTE are: superficial neurofibrillary tangles (NFTs); p–tau in CA2 and CA4 hippocampus; p-tau in: mammillary bodies, hypothalamic nuclei, amygdala, nucleus accumbens, thalamus, midbrain tegmentum, nucleus basalis of Meynert, raphe nuclei, substantia nigra and locus coeruleus; p-tau thorn-shaped astrocytes (TSA) in the subpial region; p-tau dot-like neurites. Purely astrocytic perivascular p-tau pathology represents ARTAG and does not meet the criteria for CTE.
A small group of individuals with CTE have chronic traumatic encephalomyopathy (CTEM), which is characterized by symptoms of motor-neuron disease and which mimics amyotrophic lateral sclerosis (ALS). Progressive muscle weakness and balance and gait problems (problems with walking) seem to be early signs of CTEM.Exosome vesicles created by the brain are potential biomarkers of TBI, including CTE.
Loss of
neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. ...
s, scarring of brain tissue, collection of
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 ...
aceous senile plaques,
hydrocephalus
Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary inc ...
, attenuation of the
corpus callosum
The corpus callosum (Latin for "tough body"), also callosal commissure, is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers, beneath the cerebral cortex in the brain. The corpus callosum is only found in placental m ...
,
diffuse axonal injury
Diffuse axonal injury (DAI) is a brain injury in which scattered lesions occur over a widespread area in white matter tracts as well as grey matter. DAI is one of the most common and devastating types of traumatic brain injury and is a major cause ...
, neurofibrillary tangles, and damage to the cerebellum are implicated in the syndrome. Neurofibrillary tangles have been found in the brains of dementia pugilistica patients, but not in the same distribution as is usually found in people with Alzheimer's. One group examined slices of brain from patients having had multiple mild traumatic brain injuries and found changes in the cells'
cytoskeleton
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is com ...
s, which they suggested might be due to damage to cerebral blood vessels.
Increased exposure to concussions and subconcussive blows is regarded as the most important risk factor. This exposure can depend on the total number of fights, number of knockout losses, the duration of career, fight frequency, age of retirement, and boxing style.
Diagnosis
Diagnosis of CTE cannot be made in living individuals; a clear diagnosis is only possible during an autopsy. Though there are signs and symptoms some researchers associate with CTE, there is no definitive test to prove the existence in a living person. Signs are also very similar to that of other neurological conditions such as Alzheimer's.
The lack of distinct
biomarker
In biomedical contexts, a biomarker, or biological marker, is a measurable indicator of some biological state or condition. Biomarkers are often measured and evaluated using blood, urine, or soft tissues to examine normal biological processes, p ...
s is the reason CTE cannot typically be diagnosed while a person is alive. Concussions are non-structural injuries and do not result in brain bleeding, which is why most concussions cannot be seen on routine neuroimaging tests such as CT or MRI. Acute concussion symptoms (those that occur shortly after an injury) should not be confused with CTE. Differentiating between prolonged post-concussion syndrome (PCS, where symptoms begin shortly after a concussion and last for weeks, months, and sometimes even years) and CTE symptoms can be difficult. Research studies are examining whether neuroimaging can detect subtle changes in
axon
An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action p ...
al integrity and structural lesions that can occur in CTE. By the early 2010s, more progress in in-vivo diagnostic techniques for CTE had been made, using DTI,
fMRI
Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area ...
,
MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
, and
MRS
Mrs. (American English) or Mrs (British English; standard English pronunciation: ) is a commonly used English honorific for women, usually for those who are married and who do not instead use another title (or rank), such as ''Doctor'', ''Prof ...
imaging; however, more research needs to be done before any such techniques can be validated.
PET
A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive appearances, intelligence ...
tracers that bind specifically to
tau protein
The tau proteins (abbreviated from tubulin associated unit) are a group of six highly soluble protein isoforms produced by alternative splicing from the gene ''MAPT'' (microtubule-associated protein tau). They have roles primarily in maintaining ...
are desired to aid diagnosis of CTE in living individuals. One candidate is the tracer , which is retained in the brain in individuals with a number of dementing disorders such as Alzheimer's disease,
Down syndrome
Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...
,
progressive supranuclear palsy
Progressive supranuclear palsy (PSP) is a late-onset degenerative disease involving the gradual deterioration and death of specific volumes of the brain. The condition leads to symptoms including loss of balance, slowing of movement, difficulty ...
,
corticobasal degeneration
Corticobasal degeneration (CBD) is a rare neurodegenerative disease involving the cerebral cortex and the basal ganglia. CBD symptoms typically begin in people from 50 to 70 years of age, and the average disease duration is six years. It is chara ...
Creutzfeldt–Jakob disease
Creutzfeldt–Jakob disease (CJD), also known as subacute spongiform encephalopathy or neurocognitive disorder due to prion disease, is an invariably fatal degenerative brain disorder. Early symptoms include memory problems, behavioral changes ...
. In a small study of 5 retired NFL players with cognitive and mood symptoms, the PET scans revealed accumulation of the tracer in their brains. However, binds to beta-amyloid and other proteins as well. Moreover, the sites in the brain where the tracer was retained were not consistent with the known neuropathology of CTE. A more promising candidate is the tracer 18F">sup>18FT807, which binds only to tau. It is being tested in several clinical trials.
A putative biomarker for CTE is the presence in serum of autoantibodies against the brain. The autoantibodies were detected in football players who experienced a large number of head hits but no concussions, suggesting that even sub-concussive episodes may be damaging to the brain. The autoantibodies may enter the brain by means of a disrupted blood-brain barrier, and attack neuronal cells which are normally protected from an immune onslaught. Given the large numbers of neurons present in the brain (86 billion), and considering the poor penetration of antibodies across a normal blood-brain barrier, there is an extended period of time between the initial events (head hits) and the development of any signs or symptoms. Nevertheless, autoimmune changes in blood of players may constitute the earliest measurable event predicting CTE.
According to 2017 study on brains of deceased gridiron football players, 99% of tested brains of NFL players, 88% of CFL players, 64% of semi-professional players, 91% of college football players, and 21% of
high school football
High school football (french: football au lycée) is gridiron football played by high school teams in the United States and Canada. It ranks among the most popular interscholastic sports in both countries, but its popularity is declining, part ...
players had various stages of CTE. Players still alive are not able to be tested.
In order to help those suffering with possible CTE, the Patrick Risha CTE Awareness Foundation created this form to help patients identify symptoms and alert doctors for impactful care.
Imaging
Although the diagnosis of CTE cannot be determined by imaging, the effects of head trauma may be seen with the use of structural imaging. Imaging techniques include the use of magnetic resonance imaging,
nuclear magnetic resonance spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a spectroscopic technique to observe local magnetic fields around atomic nuclei. The sample is placed in a magnetic fie ...
Diffusion MRI
Diffusion-weighted magnetic resonance imaging (DWI or DW-MRI) is the use of specific MRI sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in MR images. It ...
The use of helmets and mouth-guards has been put forward as a possible preventative measure; though neither has significant research to support its use, both have been shown to reduce direct head trauma. Although there is no significant research to support the use of helmets to reduce the risk of concussions, there is evidence to support that helmet use reduces impact forces. Mouth guards have been shown to decrease dental injuries, but again have not shown significant evidence to reduce concussions. Because repeated impacts are thought to increase the likelihood of CTE development, a growing area of practice is improved recognition and treatment for concussions and other head trauma; removal from sport participation during recovery from these traumatic injuries is essential. Proper return-to-play protocol after possible brain injuries is also important in decreasing the significance of future impacts.
Efforts are being made to change the rules of contact sports to reduce the frequency and severity of blows to the head. Examples of these rule changes are the evolution of tackling technique rules in American football, such as the banning of helmet-first tackles, and the addition of rules to protect defenseless players. Likewise, another growing area of debate is better implementation of rules already in place to protect athletes.
Because of the concern that boxing may cause CTE, there is a movement among medical professionals to ban the sport. Medical professionals have called for such a ban as early as the 1950s.
Management
No cure exists for CTE, and because it cannot be tested for until an autopsy is performed, people cannot know if they have it. Treatment is supportive as with other forms of dementia. Those with CTE-related symptoms may receive medication and non-medication related treatments.
Epidemiology
Rates of disease have been found to be about 30% among those with a history of multiple head injuries. Population rates, however, are unclear.
Professional level athletes are the largest group with CTE, due to frequent concussions and sub-concussive impacts from play in
contact sport
Contact sports are sports that emphasize or require physical contact between players. Some sports, such as mixed martial arts, are scored on impacting an opponent, while others, including rugby football, gridiron football and Australian rules fo ...
. These contact-sports include
American football
American football (referred to simply as football in the United States and Canada), also known as gridiron, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team wi ...
ice hockey
Ice hockey (or simply hockey) is a team sport played on ice skates, usually on an ice skating rink with lines and markings specific to the sport. It belongs to a family of sports called hockey. In ice hockey, two opposing teams use ice h ...
,
Rugby football
Rugby football is the collective name for the team sports of rugby union and rugby league.
Canadian football and, to a lesser extent, American football were once considered forms of rugby football, but are seldom now referred to as such. The ...
(
Rugby union
Rugby union, commonly known simply as rugby, is a close-contact team sport that originated at Rugby School in the first half of the 19th century. One of the two codes of rugby football, it is based on running with the ball in hand. In it ...
and
Rugby league
Rugby league football, commonly known as just rugby league and sometimes football, footy, rugby or league, is a full-contact sport played by two teams of thirteen players on a rectangular field measuring 68 metres (75 yards) wide and 11 ...
),
boxing
Boxing (also known as "Western boxing" or "pugilism") is a combat sport in which two people, usually wearing protective gloves and other protective equipment such as hand wraps and mouthguards, throw punches at each other for a predetermine ...
mixed martial arts
Mixed martial arts (MMA), sometimes referred to as cage fighting, no holds barred (NHB), and ultimate fighting, and originally referred to as Vale Tudo is a full-contact combat sport based on striking, grappling and ground fighting, inc ...
,
association football
Association football, more commonly known as football or soccer, is a team sport played between two teams of 11 players who primarily use their feet to propel the ball around a rectangular field called a pitch. The objective of the game is ...
, and
wrestling
Wrestling is a series of combat sports involving grappling-type techniques such as clinch fighting, throws and takedowns, joint locks, pins and other grappling holds. Wrestling techniques have been incorporated into martial arts, combat ...
. In association football, only prolific headers are known to have developed CTE.
Cases of CTE were also recorded in baseball.
According to a 2017 study on brains of deceased gridiron football players, 99% of tested brains of NFL players, 88% of CFL players, 64% of semi-professional players, 91% of college football players, and 21% of
high school football
High school football (french: football au lycée) is gridiron football played by high school teams in the United States and Canada. It ranks among the most popular interscholastic sports in both countries, but its popularity is declining, part ...
players had various stages of CTE.
Other individuals diagnosed with CTE were those involved in military service, had a previous history of chronic
seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
s, were domestically abused, or were involved in activities resulting in repetitive head collisions.
History
CTE was originally studied in boxers in the 1920s as "punch-drunk syndrome." Punch-drunk syndrome was first described in 1928 by a forensic pathologist, Dr.
Harrison Stanford Martland
Harrison Stanford Martland (September 10, 1883 – May 1, 1954) was an American pathologist who identified radium as the cause of cancer and death among watch dial painters, and also coined the term '' punch drunk'' to describe chronic head injurie ...
, who was the chief medical examiner of Essex County in
Newark, New Jersey
Newark ( , ) is the most populous city in the U.S. state of New Jersey and the seat of Essex County and the second largest city within the New York metropolitan area.Journal of the American Medical Association'' article, in which he noted the tremors, slowed movement, confusion and speech problems typical of the condition. The term "punch-drunk" was replaced with "dementia pugilistica" in 1937 by J.A. Millsbaugh, as he felt the term was condescending to former boxers. The initial diagnosis of ''dementia pugilistica'' was derived from the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
word for boxer ''pugil'' (akin to ''pugnus'' 'fist', ''pugnāre'' 'to fight').
Other terms for the condition have included chronic boxer's encephalopathy, traumatic boxer's encephalopathy, boxer's dementia, pugilistic dementia, chronic traumatic brain injury associated with boxing (CTBI-B), and punch-drunk syndrome.
The seminal work on the disease came from British neurologist Macdonald Critchley, who in 1949 wrote a paper titled "Punch-drunk syndromes: the chronic traumatic encephalopathy of boxers". CTE was first recognized as affecting individuals who took considerable blows to the head, but was believed to be confined to boxers and not other athletes. As evidence pertaining to the clinical and neuropathological consequences of repeated mild head trauma grew, it became clear that this pattern of neurodegeneration was not restricted to boxers, and the term chronic traumatic encephalopathy became most widely used.
In 2002,
American football
American football (referred to simply as football in the United States and Canada), also known as gridiron, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team wi ...
player
Mike Webster
Michael Lewis Webster (March 18, 1952September 24, 2002) was an American professional football player who was a center in the National Football League (NFL) from 1974 to 1990 with the Pittsburgh Steelers and Kansas City Chiefs. He is a membe ...
died following unusual and unexplained behavior. In 2005 Nigerian-American neuropathologist Bennet Omalu, along with colleagues in the Department of Pathology at the
University of Pittsburgh
The University of Pittsburgh (Pitt) is a public state-related research university in Pittsburgh, Pennsylvania. The university is composed of 17 undergraduate and graduate schools and colleges at its urban Pittsburgh campus, home to the univers ...
, published their findings in a paper titled "Chronic Traumatic Encephalopathy in a National Football League Player", followed by a paper on a second case in 2006 describing similar pathology.
In June 2007 professional wrestler
Chris Benoit
Christopher Michael Benoit (; May 21, 1967 – June 24, 2007) was a Canadian professional wrestler. He worked for various pro-wrestling promotions during his 22-year career including most notably the World Wrestling Federation/World Wrestlin ...
murdered his wife and son before committing suicide days after appearing on television. His autopsy revealed he was in very advanced stages of CTE with his brain being said to resemble that of an 87-year-old with advanced Alzheimer's.
In 2008, the Sports Legacy Institute joined with the Boston University School of Medicine (BUSM) to form the Center for the Study of Traumatic Encephalopathy (now the BU CTE Center)."New pathology findings show significant brain degeneration in professional athletes with history of repetitive concussions" Center for the Study of Traumatic Encephalopathy, 25 September 2008.Brain Injury Research Institute (BIRI) also studies the impact of concussions.
In 2014, Patrick Grange of Albuquerque was the first US soccer player with CTE at autopsy. He was well known for his heading and had died in 2012.
In 2014, Patrick Risha was the first Dartmouth graduate diagnosed with CTE. His family started the website StopCTE.org and they spread awareness in his honor on CTE Awareness Day ever January 30
On April 7, 2021, former
National Football League
The National Football League (NFL) is a professional American football league that consists of 32 teams, divided equally between the American Football Conference (AFC) and the National Football Conference (NFC). The NFL is one of the ...
player
Phillip Adams
Phillip Adams, Philip Adams, or Phil Adams may refer to:
Sports
* Phillip Adams (American football) (1988–2021), American football cornerback
* Phillip Adams (sport shooter) (born 1945), Australian pistol shooter
* Phil Adams (cricketer) (born 1 ...
was found to have shot and killed six people, before killing himself a day later. A subsequent autopsy revealed at that the time of the shooting, Adams had an "unusually severe" case of chronic traumatic encephalopathy.
In October 2022. the United States
National Institutes of Health
The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...
formally acknowledged there was a causal link between repeated blows to the head and CTE.
Research
In 2005, forensic pathologist Bennet Omalu, along with colleagues in the Department of Pathology at the University of Pittsburgh, published a paper, "Chronic Traumatic Encephalopathy in a National Football League Player", in the journal ''Neurosurgery'', based on analysis of the brain of deceased former NFL center
Mike Webster
Michael Lewis Webster (March 18, 1952September 24, 2002) was an American professional football player who was a center in the National Football League (NFL) from 1974 to 1990 with the Pittsburgh Steelers and Kansas City Chiefs. He is a membe ...
. This was then followed by a paper on a second case in 2006 describing similar pathology, based on findings in the brain of former NFL player Terry Long.
In 2008, the Center for the Study of Traumatic Encephalopathy at the BU School of Medicine (now the BU CTE Center) started the VA-BU-CLF Brain Bank at the Bedford Veterans Administration Hospital to analyze the effects of CTE and other neurodegenerative diseases on the brain and spinal cord of athletes, military veterans, and civilians. To date, the VA-BU-CLF Brain Bank is the largest CTE tissue repository in the world, with over 1000 brain donors.
On 21 December 2009, the
National Football League Players Association
The National Football League Players Association, or NFLPA, is a labor union representing National Football League (NFL) players. The NFLPA, which has headquarters in Washington, D.C., is led by president J. C. Tretter and executive director DeM ...
announced that it would collaborate with the BU CTE Center to support the center's study of repetitive brain trauma in athletes. Additionally, in 2010 the
National Football League
The National Football League (NFL) is a professional American football league that consists of 32 teams, divided equally between the American Football Conference (AFC) and the National Football Conference (NFC). The NFL is one of the ...
gave the BU CTE Center a $1 million gift with no strings attached. In 2008, twelve living athletes (active and retired), including hockey players
Pat LaFontaine
Patrick Michael LaFontaine (born February 22, 1965) is an American former ice hockey center who played in the National Hockey League (NHL) and spent his entire playing career with the league's New York State-based teams.
LaFontaine played for th ...
Ted Johnson
Ted Curtis Johnson (born December 4, 1972) is a former American football player in the National Football League (NFL). He grew up in Carlsbad, California where he graduated from Carlsbad High School in 1991. From there he attended the Universi ...
, committed to donate their brains to VA-BU-CLF Brain Bank after their deaths. In 2009, NFL Pro Bowlers
Matt Birk
Matthew Robert Birk (born July 23, 1976) is a former American football center who played in the National Football League (NFL) for 14 seasons. He spent most of his professional career playing for the Minnesota Vikings. He was the Republican nom ...
, Lofa Tatupu, and Sean Morey pledged to donate their brains to the VA-BU-CLF Brain Bank.
In 2010, 20 more NFL players and former players pledged to join the VA-BU-CLF Brain Donation Registry, including Chicago Bears linebacker Hunter Hillenmeyer, Hall of Famer Mike Haynes, Pro Bowlers
Zach Thomas
Zachary Michael Thomas (born September 1, 1973) is an American former professional football player who was a middle linebacker in the National Football League (NFL) for 13 seasons. He played college football for Texas Tech University, and was ...
,
Kyle Turley
Kyle John Turley (born September 24, 1975) is a former American football offensive tackle who played nine seasons in the National Football League (NFL). Selected 7th overall in the 1998 NFL draft, Turley played five seasons for the New Orleans ...
, and
Conrad Dobler
Conrad Francis Dobler (born October 1, 1950) is a former American football guard who played in the National Football League (NFL) for 10 seasons, primarily with the St. Louis Cardinals. He was selected in the fifth round of the 1972 NFL Draft by ...
, Super Bowl Champion
Don Hasselbeck
Donald William Hasselbeck (born April 1, 1955) is a former professional football player, a tight end in the National Football League (NFL) for the New England Patriots, Los Angeles Raiders, Minnesota Vikings, and the New York Giants.
Early life ...
and former pro players
Lew Carpenter
Lewis Glen Carpenter (January 12, 1932 – November 14, 2010) was an American football player and coach. He played college football for the University of Arkansas and professionally for ten seasons in the National Football League (NFL) as a ...
Mick Foley
Michael Francis Foley (born June 7, 1965) is an American actor, author, retired professional wrestler, and color commentator. He is currently signed to WWE under the company's Legends program, acting as a company ambassador.
Foley worked for m ...
Matt Morgan
Matthew Thomas Morgan (born September 10, 1976) is an American politician, actor and retired Professional wrestling, professional wrestler. He is a current City Commissioner in Longwood, Florida. He is known for his time in Total Nonstop Actio ...
also agreed to donate their brains upon their deaths. Also in 2010, MLS player
Taylor Twellman
Taylor Timothy Twellman (born February 29, 1980) is an American former soccer player who played professionally from 1999 to 2010. He now works in the media as a soccer television commentator.
Twellman is best known for his play with the New Eng ...
, who had to retire from the New England Revolution because of post-concussion symptoms, agreed to donate his brain upon his death. As of 2010, the VA-BU-CLF Brain Donation Registry consists of over 250 current and former athletes.
In 2011, former
North Queensland Cowboys
The North Queensland Cowboys is an Australian professional rugby league football club based in Townsville, the largest town in North Queensland. They compete in Australia's premier rugby league competition, the National Rugby League (NRL).
Sinc ...
National Rugby League
The National Rugby League (NRL) is an Australasian rugby league club competition which contains clubs from New South Wales, Queensland, Victoria, the Australian Capital Territory and New Zealand. The NRL formed in 1998 as a joint partnership ...
player to agree to donate his brain upon his death, in response to recent concerns about the effects of concussions on Rugby League players, who do not use helmets. Also in 2011, boxer
Micky Ward
George Michael Ward Jr. (born October 4, 1965), often known by his nickname, "Irish" Micky Ward, is an American former professional boxer who competed from 1985 to 2003. He challenged once for the IBF light welterweight title in 1997, and held ...
, whose career inspired the film ''
The Fighter
''The Fighter'' is a 2010 American biographical sports drama film directed by David O. Russell, and stars Mark Wahlberg (who also produced), Christian Bale, Amy Adams, and Melissa Leo. The film centers on the lives of professional boxer Mi ...
'', agreed to donate his brain upon his death. In 2018, NASCAR driver
Dale Earnhardt Jr.
Ralph Dale Earnhardt Jr. (born October 10, 1974) is an American semi-retired professional stock car racing driver, team owner, author, and an analyst for '' NASCAR on NBC''. He currently competes part-time in the NASCAR Xfinity Series, driving ...
, who retired in 2017 citing multiple concussions, became the first auto racing competitor agreeing to donate his brain upon his death.
In related research, the Center for the Study of Retired Athletes, which is part of the Department of Exercise and Sport Science at the
University of North Carolina at Chapel Hill
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States ...
, is conducting research funded by National Football League Charities to "study former football players, a population with a high prevalence of exposure to prior Mild Traumatic Brain Injury (MTBI) and sub-concussive impacts, in order to investigate the association between increased football exposure and recurrent MTBI and neurodegenerative disorders such as cognitive impairment and Alzheimer's disease (AD)".
In February 2011, former NFL player Dave Duerson committed suicide via a gunshot to his chest, thus leaving his brain intact.Smith, Michael David "Boston researchers request Junior Seau's brain"
NBC
The National Broadcasting Company (NBC) is an American English-language commercial broadcast television and radio network. The flagship property of the NBC Entertainment division of NBCUniversal, a division of Comcast, its headquarters are l ...
Sports Pro Football Talk, 3 May 2012. Retrieved 3 May 2012. Duerson left text messages to loved ones asking that his brain be donated to research for CTE. The family got in touch with representatives of the
Boston University
Boston University (BU) is a Private university, private research university in Boston, Massachusetts. The university is nonsectarian, but has a historical affiliation with the United Methodist Church. It was founded in 1839 by Methodists with ...
center studying the condition, said Robert Stern, the co-director of the research group. Stern said Duerson's gift was the first time of which he was aware that such a request had been made by someone who had committed suicide that was potentially linked to CTE. Stern and his colleagues found high levels of the protein tau in Duerson's brain. These elevated levels, which were abnormally clumped and pooled along the brain sulci, are indicative of CTE.
In July 2010, NHL enforcer
Bob Probert
Robert Alan Probert (June 5, 1965 – July 5, 2010) was a Canadian professional ice hockey forward. Probert played for the National Hockey League's Detroit Red Wings and Chicago Blackhawks. While a successful player by some measures, including be ...
died of heart failure. Before his death, he asked his wife to donate his brain to CTE research because it was noticed that Probert experienced a mental decline in his 40s. In March 2011, researchers at Boston University concluded that Probert had CTE upon analysis of the brain tissue he donated. He was the second NHL player from the program at the BU CTE Center to be diagnosed with CTE postmortem.
The BU CTE Center has also found indications of links between amyotrophic lateral sclerosis (ALS) and CTE in athletes who have participated in contact sports. Tissue for the study was donated by twelve athletes and their families to the VA-BU-CLF Brain Bank at the Bedford, Massachusetts VA Medical Center.
In 2013,
President Barack Obama
Barack Hussein Obama II ( ; born August 4, 1961) is an American politician who served as the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, Obama was the first African-American president of the ...
announced the creation of the Chronic Effects of Neurotrauma Consortium or CENC, a federally funded research project devised to address the long-term effects of mild
traumatic brain injury
A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic br ...
veterans
A veteran () is a person who has significant experience (and is usually adept and esteemed) and expertise in a particular occupation or field. A military veteran is a person who is no longer serving in a military.
A military veteran that h ...
. The CENC is a multi-center collaboration linking premiere basic science, translational, and clinical neuroscience researchers from the DoD, VA, academic universities, and private research institutes to effectively address the scientific, diagnostic, and therapeutic ramifications of mild TBI and its long-term effects.
Nearly 20% of the more than 2.5 million U.S. service members (SMs) deployed since 2003 to Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) have sustained at least one
traumatic brain injury
A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic br ...
(TBI), predominantly mild TBI (mTBI), and almost 8% of all OEF/OIF Veterans demonstrate persistent post-TBI symptoms more than six months post-injury. Unlike those head injuries incurred in most sporting events, recent military head injuries are most often the result of blast wave exposure. After a competitive application process, a consortium led by
Virginia Commonwealth University
Virginia Commonwealth University (VCU) is a public research university in Richmond, Virginia. VCU was founded in 1838 as the medical department of Hampden–Sydney College, becoming the Medical College of Virginia in 1854. In 1968, the Virginia ...
was awarded funding.
The project principal investigator for the CENC is David Cifu, chairman and Herman J. Flax professor of the Department of
Physical Medicine and Rehabilitation
Physical medicine and rehabilitation, also known as physiatry, is a branch of medicine that aims to enhance and restore functional ability and quality of life to people with physical impairments or disabilities. This can include conditions su ...
(PM&R) at
Virginia Commonwealth University
Virginia Commonwealth University (VCU) is a public research university in Richmond, Virginia. VCU was founded in 1838 as the medical department of Hampden–Sydney College, becoming the Medical College of Virginia in 1854. In 1968, the Virginia ...
(VCU) in Richmond, Virginia, with co-principal investigators Ramon Diaz-Arrastia, Professor of Neurology,
Uniformed Services University of the Health Sciences
Uniformed Services University of the Health Sciences (USU) is a health science university of the U.S. federal government. The primary mission of the school is to prepare graduates for service to the U.S. at home and abroad in the medical corps as ...
, and Rick L. Williams, statistician at
RTI International
Research Triangle Institute, trading as RTI International, is a nonprofit organization headquartered in the Research Triangle Park in North Carolina. RTI provides research and technical services. It was founded in 1958 with $500,000 in funding fr ...
.
In 2017,
Aaron Hernandez
Aaron Josef Hernandez (November 6, 1989 April 19, 2017) was an American football tight end. He played in the National Football League (NFL) for three seasons with the New England Patriots until his career came to an abrupt end after his arrest ...
, a former professional football player and convicted murderer, committed suicide at the age of 27 while in prison. His family donated his brain to the BU CTE Center. Ann McKee, the head of Center, concluded that "Hernandez had Stage 3 CTE, which researchers had never seen in a brain younger than 46 years old."
Research into the genetic component of CTE is evolving, and well summarized in a recent review. Interestingly, the minor allele of
TMEM106B Transmembrane protein 106B is a protein that is encoded by the ''TMEM106B'' gene. It is found primarily within neurons and oligodendrocytes in the central nervous system with its subcellular location being in lysosomal membranes. TMEM106B helps fa ...
has been found to be associated with a protective phenotype.
See also
*
Acquired brain injury
Acquired brain injury (ABI) is brain damage caused by events after birth, rather than as part of a genetic or congenital disorder such as fetal alcohol syndrome, perinatal illness or perinatal hypoxia. ABI can result in cognitive, physical, e ...
Concussions in American football
Concussions and play-related head blows in American football have been shown to be the cause of chronic traumatic encephalopathy (CTE), which has led to player deaths and other debilitating symptoms after retirement, including memory loss, depress ...
Brendan Schaub
Brendan Peter Schaub (born March 18, 1983) is an American podcast host, former professional mixed martial artist, and stand-up comedian. He is the host of ''The Fighter and the Kid'' podcast, the ''Below the Belt with Brendan Schaub'' podcast, ...
List of NFL players with chronic traumatic encephalopathy
A large number of former National Football League (NFL) players have been diagnosed with or have had chronic traumatic encephalopathy, or CTE. A definitive diagnosis so far can be made only post-mortem. However, an increasing number of former playe ...
Traumatic brain injury
A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic br ...