December 10, 2007

ALS More Common in People With Head Injuries

Having multiple head injuries severe enough to require medical attention appears to be a risk factor for development of amyotrophic lateral sclerosis (ALS), according to a recently released study by the National Institute of Environmental Health Sciences (NIEHS) of the National Institutes of Health (NIH).

The study supports previous observations from other studies, including one that found an elevated incidence of ALS in Italian soccer players.

NIEHS scientist Honglei Chen and colleagues, who published their findings Oct. 1 in the American Journal of Epidemiology, compared 109 people with ALS in the New England area with 255 people without ALS, matching the study participants with respect to age, gender and region of New England.

After controlling for these and other factors, those who had sustained more than one severe head injury, with the last one occurring within the previous 10 years, developed ALS 11 times more often than those who had never sustained a severe head injury. The authors, however, interpreted their results cautiously, since the analyses were based on small numbers. 

People who had sustained just one head injury developed ALS at about the same rate as those who had never had a head injury.

Injuries to other parts of the body were not correlated with the development of ALS.

The investigators say they don’t know how head injury might be a risk factor for ALS, but that there are several possibilities. They say inflammation of the injured area, disruption of the normal barrier between the circulatory system and the brain (the blood-brain barrier), and damage to the energy-producing centers inside cells (known as the mitochondria) should all be considered.

They say studies with larger numbers should be undertaken, and that investigators should collect more detailed information about each episode of head injury.