Repeated Boxing Head Injuries Cause Brain Shrinkage

The pursuit of glory in the boxing ring comes with long-term consequences like chronic traumatic encephalopathy (CTE), which one new study shows can shrink fighters’ brains.

The research adds to the large and growing body of evidence showing how dangerous combat and contact sports can be for brain health, linking shrinking brain regions to Parkinson’s disease, other neurological disorders, psychiatric disturbances, and even early death.

Researchers for the study, published in Neurology, pulled 204 active and retired boxers from the Professional Fighters Brain Health Study, a long-term observational study of professional fighters and controls who are not involved in combat sports.

The study demonstrates that three different brain regions shrink in active boxers compared with controls. The degree of shrinkage and the different regions that shrank suggest that several disease processes related to repetitive head injury may be attacking the gray matter together, the study states.

Furthermore, shrinkage was more pronounced among retired fighters, suggesting the more trauma fighters sustain, equals more long-term consequences for brain health.

The study also measured blood levels of two proteins that indicate brain injury or neurological malfunction. Both were elevated in boxers compared with controls.

“The correlation between boxing and CTE should be expected because the goal of the sport is to inflict a concussion upon the opponent, but what about soccer players or non-athletes who are unlucky enough to sustain repeated concussions?” asks MedicineNet author Benjamin Wedro, MD, FACEP, FAAEM. “The specter of long-term disability overshadows the pursuit of athletic glory, especially when the symptoms may be delayed by decades.”

What Is Chronic Traumatic Encephalopathy?

Chronic traumatic encephalopathy describes a gradual degeneration in brain function due to repeated head injuries that causes both concussions with symptoms and concussions that do not cause symptoms, Dr. Wedro said.

Once the initial symptoms of concussion have faded, months and years later, new symptoms occur. CTE symptoms start slowly and creep up on the patient. Initially, there may be concentration and memory problems with episodes of disorientation and confusion, dizziness, and headache. It is as if the concussion symptoms were starting to return even without a new head injury, Dr. Wedro said.

The patient can become aggressive and psychotic. As CTE progresses, behavior becomes even more erratic, with aggression and symptoms similar to those of Parkinson’s disease. Finally, thought processes decrease even further, leading to a dementia with more Parkinson’s symptoms including speech and walking abnormalities. The symptoms are progressive and cannot be stopped, Dr. Wedro said.

Victims of CTE seem to be more prone to death because of alcohol or drug overdose and suicide. Over the past decade, the suicide deaths of NFL football players Junior Seau, Ray Easterling, and Dave Duerson and NHL hockey players Derek Boogaard, Wade Belak, and Rick Rypien brought the specter of CTE and chronic head injury to the front page, Dr. Wedro said.

The diagnosis of CTE is tough to make clinically. No bleeding or other major abnormalities are visible on CT scan and CTE appears to act like other diseases that attack brain function. It can be confirmed by autopsy and dissection of the brain but that doesn’t particularly help the patient. An abnormal protein called tau builds up in the brain and causes abnormal nerve fibers and cell tangles. These abnormalities look different than those in an Alzheimer’s brain in which loss of brain tissue is routinely seen, Dr. Wedro said.

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