Eating fish weekly may slow memory loss, study shows


CHICAGO -- Eating fish once a week slows the memory loss associated with aging by 10 percent a year, according to a Rush University Medical Center study of 6,158 elderly Chicago residents.

For people who eat more than one fish meal a week, the slowdown in memory loss amounted to 13 percent a year, Rush epidemiologist Martha Clare Morris reported yesterday in the online version of the medical journal Archives of Neurology.

Analyses of diet, lifestyle and cognitive function found that after six years, those who consumed fish weekly were three to four years younger mentally than those who seldom ate fish, she said.

Biologically, the findings make sense because fish contain omega-3 fatty acid, an important component of brain cell membranes, said Alice Lichtenstein, director of the cardiovascular nutrition laboratory at the U.S. Department of Agriculture's Human Nutrition Research Center on Aging at Tufts University.

Lichtenstein, who was not involved in the Rush study, said the findings are consistent with other studies finding that eating fish or taking fish oil supplements lowers the risk of heart attack, stroke and Alzheimer's disease.

"Basically, we found that eating fish at least once a week appears to have a small but significant delay in the decline of one's thinking ability with age," Morris said. There were too few people taking fish oil supplements to measure their effect on memory.

Morris said the study was not designed to look at possible effects of mercury contamination of fish, which has been linked to cognitive impairment. But it is probably a good idea to be aware of reports on which fish might contain the highest mercury levels, she said. Fish that tend to have higher mercury content include swordfish and tuna.

The study group was made up of 62 percent blacks and 38 percent whites, and the lowered risk of memory loss was observed in both races, Morris said.

"We know that as we grow older, the neurons lose omega-3 fatty acid," Morris said. "By eating fish or other sources of omega-3 fatty acid, you can replace that which is lost in the neuron membranes. That's very important for neuron functioning and how they communicate among themselves."

Ronald Kotulak writes for the Chicago Tribune.

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