'The rate of [cognitive] decline was reduced by 10 percent to 13 percent per year among persons who consumed one or more fish meals per week....equivalent of being three to four years younger in age.'

Fish are rich in omega-3 fatty acids, which are essential for neurocognitive development and normal brain functioning, the article notes. Eating fish has been linked to lower risk of dementia and stroke in previous research. Also, one omega-3 fatty acid in particular -- docosahexaenoic acid (DHA) -- has been found to be important for memory performance in aged animals in recent studies.

Like Being a Few Years Younger

Martha Clare Morris, ScD, of Rush University Medical Center, Chicago, and colleagues analyzed six years of data from an ongoing study of Chicago residents aged 65 years and older. They initially were interviewed between 1993 and 1997, and two follow-up interviews were conducted at three-year intervals.

The participants completed four standardized cognitive tests and supplied information on how often they ate 139 different foods. They also answered questions regarding their daily activities, exercise levels, alcohol consumption and medical histories.

"Dietary intake of fish was inversely associated with cognitive decline over six years in this older, biracial community study," report the researchers.

"The rate of decline was reduced by 10 percent to 13 percent per year among persons who consumed one or more fish meals per week compared with those with less than weekly consumption. The rate reduction is the equivalent of being three to four years younger in age," they note.

Pathological or Normal Aging?

The rate differences in cognitive decline were not associated with overall dietary patterns. Even after adjusting for the amount of fruit and vegetables consumed, the link to fish consumption remained the same.

"Cognitive decline is common among older people and is very much associated with advancing age," the authors write.

"Our data offer no insight as to whether this cognitive decline is pathological or the result of a normal aging process. Nonetheless, data from the United States and other countries indicate that it is a widespread and increasing public health problem," they point out.

"This study suggests that eating one or more fish meals per week may protect against cognitive decline associated with older age," the authors conclude. "More precise studies of the different dietary constituents of fish should help to understand the nature of the association."