PNR&D study links agricultural chemicals to ALS

A study by University of Michigan researchers has shown a link between agricultural chemicals and amyotrophic lateral sclerosis, a finding that has attracted the federal Centers for Disease Control to fund the study’s expansion.

The association of pesticides and fertilizer exposure to ALS, or Lou Gehrig’s disease, was found in the first 66 ALS patients in the interim analysis of a larger study that will ultimately pair more than 400 ALS patients with an equal number of unafflicted, age-matched participants. The study, which relies on numerous tissue samples from participants, is being conducted by the University of Michigan’s Program for Neurology Research & Discovery, headed by neurologist Eva L. Feldman, M.D., Ph.D.

The results of the first cohort were reported in the paper titled “Environmental Risk Factors and Amyotrophic Lateral Sclerosis (ALS): A Case-control Study of ALS in Michigan.” It was published June 30 in PLOS ONE, a peer-reviewed open-access scientific journal. The interim analysis was based on 66 pairs of age-matched ALS patients and unafflicted controls, and for the first time showed a link between agricultural chemicals and ALS, also known as Lou Gehrig’s disease.

“It is far too early to draw conclusions, but the fact that we’ve made this correlation between common agricultural chemicals and ALS for the first time ever is extremely promising,” said Eva Feldman, M.D., Ph.D., the study’s corresponding author. “We need to gather more data, and if these findings hold up we may find a path toward better understanding this mysterious and incurable disease.”

Michigan is known to have “clusters” where the prevalence of ALS is higher than is typically found elsewhere, and researchers are trying to understand why certain people contract ALS while others don’t. The study was designed to compare exposure to a number of chemicals over various time frames between ALS patients and controls. Subjects supplied urine samples so researchers could get a snapshot of chemical exposures in the immediate time frame, and blood samples to determine exposures over 10- and 30-year periods. The study was novel in its use of different exposure periods.

Smoking, occupational exposures to industrial metals, dust and gas, radiation and physical activity were not associated with ALS in the interim analysis. The study is expected to continue into 2015. To participate in the study, contact study coordinator Blake Swihart, at (734) 763-8284 or blakeswi@med.umich.edu.

Amyotrophic lateral sclerosis is characterized by the progressive deterioration of large motor neurons that control muscle function. Patients first develop limb weakness, followed by difficulty speaking and swallowing. As the disease progresses, it retards the patient’s ability to breathe. ALS patients typically die within three years of diagnosis. At any given time, about 50,000 people are afflicted with ALS worldwide. Its causes are unknown and there is no cure.

Funding support for the ALS study was provided by the Agency for Toxic Substances and Disease Registry, the National Institutes of Health, the University of Michigan MCubed funding program, and the A. Alfred Taubman Medical Research Institute.