Additional Information on New Study that Suggests a Potential Relationship Between Head Trauma and Motor Neuron Diseases

The study published in the Journal of Neuropathology and Experimental Neurology states that epidemiological evidence suggests that the incidence of an ALS-like motor neuron disease may be increased in association with repeated head injury.  Of 12 cases studied (athletes who had been exposed to head trauma and strenuous exercise), ten cases had widespread TAR DNA-binding protein (TDP-43), and three of the 10 athletes also developed “a progressive motor neuron disease” that mimics ALS also known as Lou Gehrig’s Disease.

Boston University researchers found these toxic proteins in the spinal cords of the three athletes.  These same proteins have been found in the brains of athletes with chronic traumatic encephalopathy (CTE), a disease linked to head injuries that causes cognitive decline, abnormal behavior and dementia.

Ann McKee, M.D., a neurology professor at Boston University who has studied CTE in athletes, noticed that an unusually high number of football players seemed to be affected by ALS, the disease which attacks nerve cells in the brain and spinal cord and destroys the ability to move and speak.

“These results are very exciting,” said ALS Association Chief Scientist Lucie Bruijn, Ph.D.  “However, because of the small number of cases involved in the study, conclusive results are highly speculative until additional studies are conducted.”

ALS is a complex disease, or syndrome, with multiple causes and can manifest itself in a variety of ways.  Head trauma is one of several environmental factors that have been suspected to influence the development of ALS; however, this has not been proven.

CTE is usually characterized by cognitive and behavioral symptoms after head injuries and can be observed, during an autopsy, in the brain.  However, ALS symptoms typically include muscle weakness and paralysis with abnormalities primarily seen in the spinal cord.

Of the three athletes involved in the study who developed ALS several years before death, two were professional football players and one was a boxer.  The report suggests that the play of contact sports, including boxing, football, and hockey, might be associated with a widespread TDP-43 proteinopathy that, in some individuals, is manifest as ALS.

However, the New York Times article published on August 17, 2010, suggested that New York Yankee legion Lou Gehrig may have had CTE rather than ALS.  Again, this is highly speculative even if Gehrig received head injuries during his career, particularly because Gehrig never displayed any the cognitive dysfunction associated with CTE.  In fact, it is important to note the study makes no mention of Lou Gehrig or baseball.

That said, people could wonder whether this study indicates that military veterans are not at greater risk of ALS.  “The study did not examine the connection between ALS and military service,” said ALS Association Vice President of Government Relations and Public Affairs Steve Gibson.  “Numerous studies, including those from Harvard University and ones funded by the Department of Defense, the Department of Veterans Affairs, and the National Institutes of Health, have found that veterans are approximately twice as likely to develop ALS as the general public.  The ALS Association paper, ALS in the Military, available on our website (www.alsa.org), has additional information on the studies.  The Institute of Medicine, also confirmed that the evidence supports a greater risk of ALS in military veterans.”

“It’s important to note that we do not know why ALS is occurring in greater rates among military veterans,” Gibson continued.  “Head trauma may be one factor, but there are many other possibilities including excessive physical activity and exposure to neurotoxins and other environmental hazards ranging from lead in munitions to jet fuel to chemical weapons.  Consequently, there is no reason to believe that veterans will not continue to receive service connected VA benefits.”

This new study unfortunately demonstrates what we already know about ALS.  That there is a lot we do not know.  That is why additional funding is needed for research, not only to answer questions related to this study, but also to find ways to better diagnose the disease and to find treatments.