Does Mercury in Fish Contribute to Dementia? Moderate seafood consumption has been correlated with lesser incidence of Alzheimer disease according to researchers.åÊ Seafood is a source of mercury, a neurotoxin that impairs neurocognitive development. Mercury toxicity is reduced by selenium, an essential nutrient present in seafood. Martha Clare Morris, Sc.D., of Rush University Medical Center, Chicago, and colleagues examined whether seafood consumption is correlated with increased brain mercury levels and also whether seafood consumption or brain mercury levels are correlated with Alzheimer’s. Seafood intake was first measured by a food frequency questionnaire at an average of 4.5 years before death. Among 544 participants, brain mercury levels were positively correlated with the number of seafood meals consumed per week and was significantly correlated with less Alzheimer disease pathology. Fish oil supplementation had no statistically significant correlation. Although seafood consumption was correlated with higher brain levels of mercury, the higher mercury levels were not significantly correlated with increased levels of brain disease. I think bottom line. Mercury alone is bad. Mercury in fish is not. Eat more fish!