MONDAY, Oct. 10, 2005 (HealthDay News) -- Your mother probably told you that fish is brain food, and apparently she was right.
A new study finds that older people who eat fish regularly reduce their amount of cognitive decline.
Fish is a source of omega-3 fatty acids; these acids have been shown to be essential for neurocognitive development and normal brain functioning. In addition, eating fish has been associated with a lower risk of dementia and stroke.
Some recent studies have even found that one omega-3 fatty acid in particular, docosahexaenoic acid (DHA), is important for memory in older animals.
The latest report on the benefits of consuming fish appears in the Oct. 10 online issue of the Archives of Neurology.
"We found that people who ate fish one or more times a week had 13 percent slower decline in thinking ability over time," said study author Martha Clare Morris, an epidemiologist at Rush University Medical Center, in Chicago. "People who rarely eat fish have a somewhat faster decline in their thinking ability over time."
In its study, Morris's team collected data on 6,158 people aged 65 and older who lived in the south side of Chicago. All these people were part of the Chicago Health and Aging Project.
As part of the study, the participants filled out a questionnaire about what they ate. In addition, every three years during the six-year study, they had their cognitive ability tested.
The researchers found that the rate of decline among those who ate fish was reduced by 10 percent to 13 percent per year, compared with those who ate fish less than once a week. "The rate reduction is the equivalent of being three to four years younger in age," they wrote.
Morris believes that increased levels of DHA may be the reason why. In a previous study, Morris found that DHA reduced the risk of developing Alzheimer's disease. "DHA is very important for the communication between neurons, and the overall functioning of neurons," she explained.
"This early stage in the research shows that eating fish may help to slow one's decline in their thinking ability as they age," Morris said.
One expert doesn't think this study makes a conclusive case that DHA or any other omega-3 fatty acid is the reason that eating fish appears to slow a decline in thinking ability.
Previous studies have suggested increased fish intake is associated with reduced rates of cognitive decline or Alzheimer's disease, and have linked this apparent protection to increased omega-3 fatty acid intake, said Greg M. Cole, associate director of the Alzheimer's Disease Research Center at the UCLA David Geffen School of Medicine.
"This study from Morris looks at a large biracial population in Chicago and also finds reduced cognitive decline associated with increased fish intake, but doesn't find much evidence to relate this to greater omega-3 fatty acid intake," Cole noted.
"One problem is that the questionnaires on fish intake were not that highly correlated with actual blood levels of omega-3," Cole said. "These new results suggest the jury is still out on whether it is the oil in the fish, specifically the omega-3 fatty acids, that we should try to increase."
The University of California, San Francisco has more about aging and cognitive decline.