Fish is a direct source of omega-3 fatty acids, which have been shown to be essential for neurocognitive development and normal brain functioning, according to background information in the article. Fish consumption has been associated with lower risk of dementia and stroke and recent studies have suggested that consumption of one omega-3 fatty acid in particular, docosahexaenoic acid (DHA), is important for memory performance in aged animals.
Martha Clare Morris, Sc.D., of Rush University Medical Center, Chicago, and colleagues analyzed six years of data from an ongoing study of Chicago residents, 65 years and older, first interviewed between 1993 and 1997 and every three years in two follow-up interviews. Interviews included four standardized cognitive tests and dietary questions on the frequency of consumption of 139 different foods, as well as questions of daily activities, exercise levels, alcohol consumption and medical history.
"Dietary intake of fish was inversely associated with cognitive decline over six years in this older, biracial community study," the researchers report. "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." The researchers examined whether overall dietary consumption patterns accounted for the association of cognitive decline and fish consumption, but the rate differences did not change after adjusting for consumption of fruit and vegetables.
"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."
"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."
(Arch Neurol. 2005; 62: 1-5. Available pre-embargo for the media at www.jamamedia.org)
Editor's Note: This study was supported by grants from the National Institutes of Health, Bethesda, Md.
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Archives of Neurology