Seafood May Help Those At Risk of Alzheimer's
Study also finds mercury in fish isn't linked to dementia symptoms
By Karen Pallarito
TUESDAY, Feb. 2, 2016 (HealthDay News) -- Seafood lovers, a new study delivers good news on two fronts: Mercury found in fish doesn't lead to mental decline, and for certain people, a diet rich in fish might stave off Alzheimer's disease.
Researchers who examined human brains confirmed that people who eat more seafood have more mercury in their brains. But, they found no link between higher brain levels of that neurotoxin and the kind of brain damage that is typical of Alzheimer's disease and dementia.
"Everybody's saying seafood has so many health benefits, but everybody's afraid of the mercury," said lead study author Martha Clare Morris, professor of nutritional epidemiology at Rush University in Chicago.
"We saw absolutely no evidence that higher levels of mercury in the brain were associated with any of the neuropathologies associated with dementia," she said.
The researchers also found that eating moderate amounts of seafood may have a protective effect for people with a specific genetic risk for Alzheimer's disease.
The study is published in the Feb. 2 issue of the Journal of the American Medical Association.
In an editorial in the same issue, Edeltraut Kroger and Dr. Robert Laforce of Laval University in Quebec, Canada, said the finding suggests "that seafood can be consumed without substantial concern of mercury contamination diminishing its possible cognitive [mental] benefit in older adults."
But why? Is there something about the so-called long-chain "n-3" fatty acids in fish that protects the brain?
Fish intake, particularly as part of a healthy diet, such as the Mediterranean diet, has been linked with decreased Alzheimer's disease or slower disease progression, Kroger said.
"It is to this day not quite clear whether the reason for the benefit of fish is to be found in its n-3 unsaturated fatty acid content, or whether the benefit from fish-containing diets is more complicated to understand," she added.
The data come from participants in Rush's Memory and Aging Project who died between 2004 and 2013. The average age at death was almost 90, and 67 percent were women. All were free of dementia at enrollment and agreed to undergo annual neurologic evaluations and brain autopsies at death.