April 6, 2016
Here’s another reminder to eat more fish. Research shows that regularly eating seafood was linked to a lower risk of brain changes typical of Alzheimer’s, especially in those at higher risk of the disease, according to a new report. And even though swordfish and other types of fish may be high in mercury, a metal that can accumulate in the brain and possibly damage nerves, eating fish containing higher levels of mercury did not appear to cause dementia-related brain abnormalities in older adults.
“Patients and their families may be hopeful that interventions such as seafood consumption may help reduce clinical manifestations of Alzheimer disease or dementia,” wrote scientists from Universite Laval in Quebec, Canada, in an editorial accompanying the study. “The report provides reassurance that seafood contamination with mercury is not related to increased brain pathology.”
Earlier studies have found that eating fish and other types of seafood at least once a week is linked to a lower risk of developing Alzheimer’s disease. This study found that seafood consumption may be especially beneficial for people who carry the E4 version of the APOE gene, which is associated with an increased risk of developing Alzheimer’s in old age. Up to 15 percent of the population carries APOE-E4, though not everyone who carries the gene variant will get Alzheimer’s.
For the study, researchers at Rush University in Chicago studied 544 men and women who were part of the Rush Memory and Aging Project, an ongoing study of elderly people in Chicago. They analyzed the brains of 286 who had died, at an average age of 90.
The researchers found that compared to people who ate little seafood, the brains of people who ate seafood at least once a week and who carried the APOE-E4 gene had lower amounts of the beta-amyloid plaques and tau tangles that are hallmarks of Alzheimer’s disease. Eating seafood did not significantly protect the brains of people who carried other forms of the APOE gene. The findings were published in JAMA, from the American Medical Association.
Though eating fish regularly was linked to higher levels of mercury in the brain, high mercury levels were not tied to dementia-related brain changes. Taking fish oil supplements were likewise not linked to brain abnormalities, the researchers found.
“Eating fatty fish may continue to be considered potentially beneficial against cognitive decline in at least a proportion of older adults, a strategy that now generally should not be affected by concerns about mercury contamination in fish,” wrote the authors of the editorial. “Such a simple strategy is encouraging in the light of the lack of evidence on protection against many neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease, another cause of dementia.”
With the numbers of Alzheimer’s cases continuing to rise with the aging population and treatments limited, there is an urgent need to pinpoint effect strategies for preventing the disease. Diet may be one way to help curb its progression.
This study provides further evidence that fish may be good for the brain. Eating fish and fish oils has been associated with slowing declines in thinking and memory skills with age and a lower risk of Alzheimer’s and other forms of dementia. A Mediterranean-style diet — rich in fish, fruit, vegetables, whole grains and heart-healthy fats like olive oil — has likewise been linked to a lower Alzheimer’s risk.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Martha Clare Morris, ScD; John Brockman, PhD; Julie A. Schneider, MD, MPH; et al: “Association of Seafood Consumption, Brain Mercury Level, and APOE ε4 Status With Brain Neuropathology in Older Adults.” JAMA Vol 315, No. 5, pages 489-497, Feb. 2, 2016
Edeltraut Kröger, PhD; Robert Laforce Jr, MD, PhD: “Fish Consumption, Brain Mercury, and Neuropathology in Patients With Alzheimer Disease and Dementi” (editorial). JAMA Vol. 315, No. 5, pages 465-466, Feb. 2, 2016