From the NYTimes,
Many studies have suggested that a diet rich in fish is good for the heart. Now there is new evidence that such a diet may ward off dementia as well. One of the largest efforts to document a connection — and the first such study undertaken in the developing world — has found that older adults in Asia and Latin America were less likely to develop dementia if they regularly consumed fish.
And the more fish they ate, the lower their risk, the report found. The findings appeared in the August issue of The American Journal of Clinical Nutrition.