Head injury may increase the risk of ALS

Last Updated: 2007-10-08 14:00:23 -0400 (Reuters Health)

NEW YORK (Reuters Health) - A history of head injury is associated with an increased risk of developing amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, according to results of a study published in the American Journal of Epidemiology.

The results of observations and studies suggest that physical trauma may be associated with a higher risk of ALS, but the evidence is far from conclusive, explains Dr. Honglei Chen, of the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, and colleagues.

To investigate, the researchers studied 109 ALS patients, diagnosed between 1993 and 1996 at two major referral centers in New England and 255 people without ALS matched to the patients (controls). The participants were asked if they had ever been injured so severely that they had required medical attention, and if so, how many times and at what ages the injuries occurred.

Overall, 46.8 percent of cases and 45.1 percent of controls reported ever experiencing a severe physical injury that required medical attention. Only head injury was associated with an elevated risk - 40 percent -- of developing ALS., the researchers found.

Compared to subjects without head injury, those with repeated head injuries and those with head injuries within the last 10 years before diagnosis were both about three-times more likely to have ALS.

Subjects with repeated head injuries with the latest occurring in the last 10 years had an 11-fold higher risk of ALS than those without head injury. Patients with head injuries were diagnosis at an earlier age than those without previous head injuries (54.0 years versus 59.5 years, respectively).

Taken together, the results are "consistent with a recent observation of higher ALS risk among Italian soccer players, and may thus suggest that repeated head injury is a risk factor for ALS," Chen told Reuters Health.

"ALS is very rare and our results were based on a small number of cases," Dr. Chen pointed out. "It is therefore important to confirm this association with a large number of cases, hopefully in a prospective study."

SOURCE: American Journal Epidemiology, September 27, 2007.