Specific brain abnormalities linked to motor neuron disease in athletes with head trauma

Aug 18 2010

Professional athletes with repetitive head trauma—and possibly others with a history of head injuries many years previously—may be prone the development of a motor neuron disease similar to amyotrophic lateral sclerosis (ALS or "Lou Gehrig's disease"), reports a study in the September Journal of Neuropathology & Experimental Neurology, official journal of the American Association of Neuropathologists, Inc. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and busines.s intelligence for students, professionals, and institutions in ww, w, allied health, pharmacy and the pharmaceutical industry.

"This is the first pathological evidence that repetitive head trauma experienced in collision sports might be associated with the development of a motor neuron disease," according to the study by Dr. Ann C. McKee of Boston University School of Medicine and colleagues.

Specific Brain Abnormalities Linked to Motor Neuron Disease in Athletes with Head Trauma
The researchers used sophisticated neuropathology techniques to study specific proteins, called tau and TDP-43, in brains obtained at autopsy from twelve former athletes. Eleven of the athletes had been professional football players or boxers; one was a hockey player.

All of the athletes had a newly characterized disease called chronic traumatic encephalopathy (CTE), with dementia developing many years after a history of repeated concussions. Previous studies have linked CTE to the deposits of tau and TDP-43 in the brain, in the absence of abnormalities typically associated with Alzheimer's disease.

In addition to CTE, three of the athletes were affected by fatal motor neuron disease, with profound and progressive muscle weakness and deterioration for several years before death. Motor neuron diseases—the most familiar of which is ALS—are characterized by degeneration of the specialized nerve cells controlling muscle movement and organ function.

The brains from patients with CTE and motor neuron disease showed specific patterns of tau and TDP-43 deposits, distinct from those of sporadic ALS. In the cases of CTE and motor neuron disease, the abnormalities included deposits of tau and TDP-43 extending into the spinal cord.

Previous studies had suggested a possible link between repetitive head trauma and the development of motor neuron disease. The new findings help to explain the association of ALS with head injury—and may provide clues as to the cause of ALS.

Of course, most people who develop ALS are not pro athletes. "The study has broad implications, not only for understanding the potential risks to professional and non-professional athletes in many types of collision sports, but also for people who serve in military combat," comments Dr. Raymond A. Sobel, Editor-in-Chief of Journal of Neuropathology & Experimental Neurology. "Anyone who experiences repetitive, seemingly mild, head injury or concussion might be at risk for developing a brain disease later in life."

Critical research questions remain, according to Dr. McKee and colleagues. It's unknown exactly how brain injury leads to protein deposits, or whether head trauma produces these changes alone or in association with certain genetic factors. The fact that symptoms don't develop for many years after head trauma may provide an opportunity for some type of treatment to block or reduce the "neurodegenerative cascade" triggered by such injuries.

The results also highlight the need for further autopsy brain studies. "We do not understand important neurological diseases such as ALS, Alzheimer disease, and Parkinson disease and we cannot diagnose them accurately other than by examination at autopsy," Dr. Sobel adds. "We can only advance research in these diseases and develop effective treatments for them by learning from autopsy studies."

Source : American Association of Neuropathologists