Dementia pugilistica

Dementia pugilistica (DP) is a type of neurodegenerative disease or dementia, which may affect amateur or professional boxers as well as athletes in other sports who suffer concussions. It is also called chronic boxer’s encephalopathy, traumatic boxer’s encephalopathy, boxer's dementia, chronic traumatic brain injury associated with boxing (CTBI-B) and punch-drunk syndrome ('punchy'), and chronic traumatic encephalopathy (CTE). Symptoms and signs of DP develop progressively over a long latent period sometimes reaching decades, with the average time of onset being about 12–16 years after the start of a career in boxing. The condition is thought to affect around 15-20% of professional boxers.

The condition is caused by repeated concussive and sub-concussive blows (blows that are below the threshold of force necessary to cause concussion), or both. Because of the concern that boxing may cause DP, there is a movement among medical professionals to ban the sport. Medical professionals have called for such a ban since as early as the 1950s.

The word pugilistica comes from the Latin root pugil, for boxer.

Symptoms
The condition, which occurs in boxers who have suffered repeated blows to the head, manifests as dementia, or declining mental ability, problems with memory, and parkinsonism, or tremors and lack of coordination. It can also cause speech problems and an unsteady gait. Patients with DP may be prone to inappropriate or explosive behavior and may display pathological jealousy or paranoia. Individuals displaying these symptoms also can be characterized as "punchy", another term for a person suffering from DP.

The brains of DP patients atrophy and lose neurons, for example in the cerebellum. The corticospinal or pyramidal tract generally dysfunctions.

Sufferers may be treated with drugs used for Alzheimer's disease and Parkinsonism.

Mechanism
It is not well understood why this syndrome occurs. Loss of neurons, scarring of brain tissue, collection of proteinaceous, senile plaques, hydrocephalus, attenuation of corpus callosum, diffuse axonal injury, neurofibrillary tangles and damage to the cerebellum are implicated in the syndrome. The condition may be etiologically related to Alzheimer's disease. Neurofibrillary tangles have been found in the brains of dementia pugilistica patients, but not in the same distribution as is usually found in Alzheimer's sufferers. One group examined slices of brain from patients who had 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.

History
DP 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 in a Journal of the American Medical Association article, in which he noted the tremors, slowed movement, confusion, and speech problems typical of the condition. In 1973, a group led by J.A. Corsellis described the typical neuropathological findings of DP after post-mortem examinations of the brains of 15 former boxers.

Famous cases
Dementia pugilistica is relatively common among boxers who had long careers and received a great many blows to the head. It is perhaps under-reported because the symptoms often do not become overt until middle age or even later, and are often indistinguishable from Alzheimer's. On the other hand, dementia pugilistica has often been falsely reported. It has been rumored that Jack Dempsey suffered from it, when in fact he retained his mental vigor until his death at 87. Joe Louis developed signs of paranoid schizophrenia that have been attributed to cocaine abuse but may also have a genetic element (his father was institutionalised for mental illness). Other ex-boxers have been said to have had dementia pugilistica when in fact they suffer from nothing worse than a working-class accent and a gruff demeanor, e.g. Rocky Graziano, Tony Zale.

However, Jimmy Ellis, Floyd Patterson (who resigned from the New York State Athletic Commission because of his deteriorating memory), Bobby Chacon, Jerry Quarry, Mike Quarry, Wilfred Benitez, Emile Griffith, Willie Pep, Freddie Roach, Sugar Ray Robinson, Billy Conn, Joe Frazier, Fritzie Zivic, and Meldrick Taylor appear to have been genuinely affected by the disorder. In addition, Muhammad Ali's Parkinson's disease was said to be caused by his boxing career, but Ali's own physician Fredie Pacheco MD states in his book 'Fight Doctor' that Ali's condition is often misquoted and that Ali in fact has Parkinson's Syndrome. However, this sort of dementia is precisely diagnosed only in autopsy, and claims of retired athletes not having DP are rarely accompanied by autopsy results. On the other hand, diagnosis of Parkinson's disease on the basis of clinical observations is 75-80% accurate..

Notably, autopsies of eleven professional American football players by Dr. Ann McKee, of Boston University School of Medicine, found CTE in all cases. CTE has been diagnosed (also by the Boston University group ) in one amateur football player, University of Pennsylvania lineman Owen Thomas, following his suicide.

Professional wrestler Chris Benoit was discovered to have suffered from CTE following his 2007 murders and subsequent suicide, as was his former colleague, Andrew Martin, following his 2009 overdose death.

Several soccer players have also developed cases over long careers, apparently because of high speed soccer ball impacts to the head. This has prompted a small movement in the sport to promote head safety gear for soccer players, especially in children's leagues.