New Study to Probe Role of Environmental Factors in ALS

SAN FRANCISCO, Nov. 20, 2001 — Lorene Nelson, an epidemiologist in the Department of Health Research at Stanford University in Stanford, Calif., along with collaborators from the University of Washington in Seattle, is studying people with amyotrophic lateral sclerosis (ALS) in order to examine environmental and lifestyle factors related to the disease.

The participants in her study are people with ALS enrolled in the Kaiser Permanente Medical Care Program of Northern California.

The epidemiological study will include a review of medical records, a personal interview, bone lead measurements and blood sample collection for genetic analysis, Nelson said Sunday at the 12th International Symposium on ALS/MND in San Francisco. The symposium is sponsored by Great Britain’s Motor Neurone Disease Association, with support from MDA.

Nelson’s new study is a larger follow-up to a case-controlled study conducted from 1990 to 1994 of some 161 people with ALS. The so-called Washington State Study found that cigarette smoking and dietary fat intake were possible contributors to a person’s overall tendency to develop ALS.

According to the earlier study, current smokers are 3.5 times more likely to have ALS than nonsmokers, and the strength of the association with ALS is directly related to the amount smoked and the number of years spent smoking. Nelson found that the likelihood of having ALS decreases with time since the last cigarette smoked, implying that quitting smoking could reduce the risk of ALS.

High dietary fat intake in the five years before diagnosis showed an even higher correlation with ALS, with a 3.8-fold increase in a person’s chance of having ALS.

"This amount is in the range of what you see for colon cancer," Nelson pointed out. A similar association between dietary fat intake and Parkinson’s disease has also been established, she said.

Other factors that might contribute in a lesser degree to the development of ALS include insecticide exposure and dietary glutamate intake, according to the first study, which was published in the American Journal of Epidemiology in January 2000. Factors found to have no positive or negative effects include heavy metals and solvents, alcohol consumption, and intake of vitamins A and C.

Most epidemiologists agree that the causes of the sporadic (nongenetic) form of ALS are likely to be multifactorial — that is, some combination of things that could include environmental exposures, lifestyle issues and genetics.