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A study just released by the U.S. Geological Society is casting doubt on the idea that toxins released by cyanobacteria blooms cause or contribute to neurological disorders such as ALS, or Lou Gehrig’s Disease – an idea that has been put forward in recent years by researchers at Dartmouth’s Geisel School of Medicine, among others.  My column next week will discuss this further.

From the USGS release about the study:

This hypothesis first emerged due to associations between dietary exposures to BMAA  (an amino acid released by cyanobacteria) and high incidence of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) in Guam. The production of BMAA in common freshwater- and ocean-dwelling cyanobacteria has led to the formation of similar hypotheses associating consumption of contaminated seafood and exposure to water during cyanobacterial blooms with globally occurring incidences of ALS, Parkinsonism, and dementia. In this study, scientists went beyond existing compilations and summaries of previous scientific literature and critically evaluated these hypotheses and associated studies. Based on this rigorous evaluation, they concluded that a causal link between these diseases and exposure to BMAA is not supported by existing data.

If true, this will be a relief to people who live near lakes and ponds that are seeing more algae blooms as the weather warms, but it would also throw a wrench into studies about a cluster of ALS cases around Lake Mascoma near Hanover. That cluster kicked off Dartmouth’s interest in the possible link between toxins and the disease in our region, as ALS doctor and researcher Elijah Stommel told the Monitor in April 2016:

“We determined there might be about a 40-fold increase in ALS incidents in that area,” Stommel said. He started wondering if there was something in the lake that was linked to the high number of cases.

“We’re finding a clustering of ALS around lakes that have cyanobacterial blooms in the summertime,” Stommel said.

The largest cluster so far documented is around Mascoma Lake, but scientists have recorded smaller clusters in northern Vermont around Lake Champlain as well as one in the Bangor, Maine, area.

The school could not be reached for comment on the USGS study Friday, a federal holiday. But I’m sure this issue will be much discussed in weeks to come.

Here’s a January 2016 story from Dartmouth about Sommel’s work.



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