…according to an article at the Journal of the American Medical Association. The study involved Chicago-area residents who had provided information about their eating habits. After death, their brains were biopsied, looking for typical pathological findings of Alzheimers Disease.
Participants who ate seafood at least once a week had fewer Alzheimers lesions in their brains, but only if they were carriers of a particular gene the predisposes to Alzheimers. The gene is called apolipoprotein E or APOE ε4.
You’ve heard that seafood may be contaminated with mercury, right? The seafood eaters in this study indeed had higher brain levels of mercury, but it didn’t cause any visible brain damage.
The Mediterranean diet, relatively rich in seafood, has long been linked to a lower risk of dementia.
A weakness of the study is that the researchers didn’t report results of clinical testing for dementia in these participants before they died. You can have microscopic evidence of Alzheimers disease on a biopsy, yet no clinical diagnosis of dementia.