Eating fish at least once a week is good for the brain, slowing age-related mental decline by the equivalent of three to four years, a study suggests.
The research adds to the growing evidence that a fish-rich diet helps keep the mind sharp. Previous studies found that people who ate fish lowered their risk of Alzheimer's disease and stroke. Fish such as salmon and tuna that are rich in omega-3 fatty acids also have been shown to prevent heart disease.
For the new study, researchers measured how well 3,718 people did on simple tests, such as recalling details of a story. The participants, all Chicago residents 65 and older, took the tests three times over six years. They also filled out a questionnaire about what they ate that included 139 foods.
The study was posted Monday on the Web site of the Archives of Neurology and will appear in the journal's December issue. It was published early online because of its general interest.
The researchers looked for, but failed to find, a link between omega-3 fatty acids and protection from brain decline. Previous studies found such a link.
Morris said it is possible that something else about eating fish worked to keep people's minds sharp. Or the food questionnaire might have been too broad to allow researchers to estimate omega-3 intakes accurately, said Dr. Pascale Barberger-Gateau, who does similar research at the University of Bordeaux in France but was not involved in the current study. A.M.