People with higher levels of metals found in their blood and urine may be more likely to be diagnosed with — and die from — amyotrophic lateral sclerosis, or ALS, a University of Michigan-led study suggests.
Researchers have known that ALS, a rare but fatal neurodegenerative condition, is influenced by genetic and environmental factors, including exposure to pesticides and metals.
This latest study examined the levels of metals in the blood and urine of people with and without ALS, finding that exposure to individual and mixtures of metals is associated with a greater risk for ALS and shorter survival.
The results are published in the Journal of Neurology, Neurosurgery, and Psychiatry.
The team measured metal levels in plasma and urine samples from over 450 people with ALS and nearly 300 people without the condition.
They found that elevated levels of individual metals, including copper, selenium and zinc, significantly associated with higher ALS risk and earlier death.
They then used these results to create environmental ALS risk scores, similar to the polygenic risk scores previously developed at U-M. The environmental risk scores indicated that mixtures of metals in plasma and urine are linked to around a three-times greater risk for the disease.
In this study, the inclusion of an ALS polygenic risk score to assess a potential moderating effect of underlying genetic factors did not alter the association between metal exposure and disease risk or survival.
“While several studies suggest that environmental factors like metals interact with genetic variants to influence the onset, progression and severity of ALS, our study found that accounting for ALS polygenic risk scores did not influence the relationship between metal exposure and ALS,” said co-author Kelly Bakulski, Ph.D., associate professor of epidemiology at the University of Michigan School of Public Health.
Investigators also discovered that participants working in occupations with a higher likelihood of metal exposure had increased levels of metal mixtures in their blood and urine.
