THE BITTER SCIENCE: Head blows from boxing can cause dementia and Alzheimer's. Can the same chronic brain injury also lead to Parkinson's?

Neurology Now
March/April 2006
Volume 2(2)
p 24–25
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While one of the world's leading neurologists was evaluating test results to determine what was ailing Muhammad Ali, the man closest to the situation was formulating his own diagnosis.

“I've been in the boxing ring for 30 years, and I've taken a lot of punches,” Ali said then, “so there is a great possibility something could be wrong.”

Ali, 42 years old at the time in 1984 and three years into retirement from boxing, was experiencing tremors, slowness of movement, slurred speech and unexplained fatigue. Neurologist Stanley Fahn, M.D., examined him at Columbia-Presbyterian Medical Center and diagnosed parkinsonism, the umbrella term for movement disorders including Parkinson's disease. The public announcement unleashed a flurry of questions: Had boxing really done this to the most graceful heavyweight champion of all time?

More than two decades later, there's still no way to determine whether boxing caused his Parkinson's; Ali may have been fated to develop this disorder even if he had been a lawyer. What is unequivocally true, however, is that professional boxing often damages the brain. Brain damage is as much an occupational hazard for boxers as black lung is for coal miners.

The term “punch drunk” entered the medical lexicon in 1928 when pathologist Harrison Martland, M.D., first described this syndrome in the Journal of the American Medical Association. “For some time,” he wrote, “fans and promoters have recognized a peculiar condition occurring among prize fighters which, in ring parlance, they speak of as ‘punch drunk.’ Fighters in whom the early symptoms are well recognized are said by the fans to be ‘cuckoo,’ ‘goofy,’ ‘cutting paper dolls,’ or ‘slug nutty.’” He estimated that half of all veteran professional boxers had the condition.

The long list of boxers who have reportedly suffered brain damage includes some of history's legendary champions — from Joe Louis, who developed dementia symptoms, to Sugar Ray Robinson, who died with Alzheimer's disease.

Figure. The location of brain damage determines the type of symptoms: Alzheimer's derives from the temporal lobe, Parkinson's from the midbrain, and behavioral problems from the frontal lobe.

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Today experts use a variety of terms in lieu of punch-drunk syndrome: chronic traumatic brain injury, chronic traumatic encephalopathy, boxer's encephalopathy and dementia pugilistica, which was coined as a medical term to describe the most severe cases.

Dr. Martland realized 78 years ago that parkinsonism was another possible result. “In severe cases,” he wrote, “there may develop a peculiar tilting of the head, a marked dragging of one or both legs, a staggering, propulsive gait with the facial characteristics of the parkinsonian syndrome, or a backward swaying of the body, tremors, vertigo and deafness.”

As with “dementia pugilistica,” the medical literature now also describes “pugilistic parkinsonism.”

“There are not too many cases of pugilistic parkinsonism, but it is an official diagnosis,” says Dr. Fahn, director of the Center for Parkinson's Disease and Other Movement Disorders at Columbia University as well as past president of the American Academy of Neurology. “Very few cases have come to our attention, and not in any other high-profile boxers that I'm aware of.”

Indeed, most victims of chronic traumatic brain injury suffer what looks more like Alzheimer's disease than Parkinson's.

There even appears to be a genetic link between Alzheimer's and traumatic brain injury. One common gene variation known as ApoE4, a genetic risk factor for Alzheimer's, has been linked to an increase in the severity of brain damage experienced by boxers with more than 12 professional bouts.

Such research suggests that some individuals may be genetically predisposed to suffer neurological damage from boxing, says neurologist Barry Jordan, M.D., director of the brain injury program at Burke Rehabilitation Hospital in White Plains, N.Y.

Chronic traumatic brain injury, Dr. Jordan says, results in three types of neurological symptoms:

* Motor—In some boxers, slightly slurred speech is one of the earliest signs of brain damage. Other common impairments to the body's motor systems include a lack of coordination, slow movements, a weakened voice, rigidity, poor coordination, poor balance and tremors.

* Cognitive—In neurological tests, afflicted boxers often exhibit poor concentration, memory deficits and slowed mental speed. “As the disease process advances, the boxer may exhibit dementia exemplified by amnesia, profound attentional defects, prominent slowness of thought, and impaired judgment, reasoning, and planning,” Dr. Jordan has written.

Figure. Even the sweetest scientist, Sugar Ray Robinson, couldn't escape the ravages of Alzheimers.

Click here to enlarge

* Behavioral—Chronic brain damage can also affect behavior. Common signs include irritability, a lack of insight, paranoia and violent outbursts.

In a 1969 British study that found one in six retired professional boxers suffered serious brain damage, symptoms began to appear an average of 16 years after a fighter's career. Those who fought longer (beyond age 28) were at greater risk, as were those with a history of losing, especially by knockout.

It's not clear exactly how “subconcussive” blows — those that don't knock a fighter out — wreak their havoc, and especially how chronic damage continues to mount decades after a boxer leaves the ring.

Joseph Friedman, M.D., professor of clinical neurosciences at Brown Medical School in Providence, R.I., likens the brain to “a bowl of Jell-O contained in a rigid case.”

“When you get hit,” he says, “you get vibrations going through there. The vibrations bounce back, because of the skull. These displacements create ripples, basically, inside the brain.” These waves, in turn, are thought to tug and stretch nerve filaments and cells. “With each of these traumas, you are presumably disrupting the normal physiology of individual nerve cells,” Friedman says. “Some of them may not recover.”

Another possibility is that repeated blows to the head cause multiple tiny hemorrhages deep inside the brain, which are eventually replaced by lesions or scarring. A third theory holds that boxing substantially disrupts the chemistry of the brain, leading to an immune response that damages the central nervous system.

“The general thought is that some type of process is initiated during a boxing career that continues after a person stops boxing,” Dr. Jordan says. “Also, I suspect, the normal aging process is superimposed on the boxing — the loss of neurons due to aging.”

The location of the damage determines a person's symptoms. Substantial damage of the substantia nigra, a portion of the midbrain, causes Parkinson-like symptoms involving muscle control. More often, diffuse damage to the temporal lobe of the cerebrum leads to symptoms that resemble Alzheimer's. Damage to the frontal lobe would explain behavioral symptoms.

Boxing is unique among sports in that injuring an opponent is an explicit goal: damaging the brain, via knockout, is by definition the pinnacle of accomplishment. This central fact — and the brain damage to which it often leads — has prompted medical organizations around the world, including the American Academy of Neurology and the American Medical Association, to call for the abolition of boxing. In 1983, the editor of the Journal of the American Medical Association called the sport an “obscenity” that “should not be sanctioned by any civilized society.”

Others, like Dr. Jordan, take a more pragmatic view, seeking to make boxing less dangerous. As chief medical officer of the New York State Athletic Commission until 1995, Dr. Jordan helped enact the strictest professional boxing rules in the world — with fighters required to undergo MRI brain scans annually. The commission bans those who lose six consecutive fights, or three in a row by knockout or technical knockout in which the referee stops the bout, from boxing in New York.

But that doesn't address the core challenge. “The problem with chronic brain injury,” Dr. Jordan explains, “is that when boxers develop it, the horse is already out of the barn. If you could find preclinical markers [signs of injury before the onset of permanent symptoms], you could advise them to stop boxing.”

Until then, chronic brain damage will remain an occupational hazard for boxers — even the greatest of them.

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