Punchdrunk

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease linked to repeated trauma to the head. The encephalopathy symptoms can include behavioral problems, mood problems, and problems with thinking. The disease often gets worse over time and can result in dementia. It is unclear if the risk of suicide is altered.

Most documented cases have occurred in athletes involved in striking-based combat sports, such as boxing, kickboxing, mixed martial arts, and Muay Thai—hence its original name ''dementia pugilistica'' (Latin for "fistfighter's dementia")—and contact sports such as American football, Australian rules football, professional wrestling, ice hockey, rugby, and association football (soccer), in semi-contact sports such as baseball and basketball, and military combat arms 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.

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, disorientation, dizziness, and headaches. Second-stage symptoms include memory loss, social instability, impulsive behavior, and poor judgment. Third and fourth stages include progressive dementia, movement disorders, hypomimia, speech impediments, sensory processing disorder, tremors, vertigo, deafness, depression and suicidality.

Additional symptoms include dysarthria, dysphagia, cognitive disorders such as amnesia, and ocular abnormalities, such as ptosis. The condition manifests as dementia, 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, 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 or paranoia.

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 such as boxing, American football, Australian rules football, wrestling, mixed martial arts, ice hockey, rugby, and association football. 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.

Pathology

The neuropathological appearance of CTE is distinguished from other tauopathies, 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 lateral ventricles and the third ventricle are often enlarged, with rare instances of dilation of the fourth ventricle. Other physical manifestations of CTE include anterior cavum septi pellucidi and posterior fenestrations, pallor of the substantia nigra and locus ceruleus, and atrophy of the olfactory bulbs, thalamus, mammillary bodies, brainstem and cerebellum. As CTE progresses, there may be marked atrophy of the hippocampus, entorhinal cortex, and amygdala.

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 neurons, scarring of brain tissue, collection of proteinaceous senile plaques, hydrocephalus, attenuation of the corpus callosum, diffuse axonal injury, 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' cytoskeletons, 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 biomarkers 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 axonal 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, MRI, and MRS imaging; however, more research needs to be done before any such techniques can be validated.

PET tracers that bind specifically to tau protein 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, progressive supranuclear palsy, corticobasal degeneration, familial frontotemporal dementia, and Creutzfeldt–Jakob disease. 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 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 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, CT scan, single-photon emission computed tomography, Diffusion MRI, and Positron emission tomography (PET). One specific use of imaging is the use of a PET scan is to evaluate for tau deposition, which has been conducted on retired NFL players.

Prevention

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. These contact-sports include American football, Australian rules football, ice hockey, Rugby football (Rugby union and Rugby league), boxing, kickboxing, mixed martial arts, association football, and wrestling. 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 players had various stages of CTE.

Other individuals diagnosed with CTE were those involved in military service, had a previous history of chronic seizures, 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, who was the chief medical examiner of Essex County in Newark, New Jersey

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