Eating fish at least once a week can reduce the risk of Alzheimer's disease, according to a new study conducted at Rush University Medical Center in Chicago, Illinois. Seafood is promoted for its many health benefits even though its contamination by mercury, a known neurotoxin, is a growing concern, the study's authors said."Our hypothesis was that seafood consumption would be associated with less neuropathology, but if there were higher levels of mercury in the brain, that would work against that. But we didn't find that at all," said lead author Martha Clare Morris, a professor of epidemiology at Rush University Medical Center. The study examined the associations of dementia neuropathologies with dietary n-3 fatty acids and mercury levels in the brain.Researchers analyzed 286 autopsied brains of 544 participants and found that brain mercury levels were positively correlated with the number of seafood meals consumed per week. Higher concentrations of mercury in the brain were not significantly correlated with increased levels of brain neuropathology, however. The study further demonstrated that moderate seafood consumption was correlated with lower levels of Alzheimer's disease neuropathology. "Although seafood consumption was also correlated with higher brain levels of mercury, these levels were not correlated with brain neuropathology," the study revealed. The study was published in the Journal of American Medical Association (JAMA).