Problems with memory and brain function, including cognitive decline, are common with aging. While many people experience at least some cognitive decline as they get older, it is not inevitable. Research has shown that by making positive lifestyle adjustments, such as remaining active and eating a healthful diet, people may be able to delay age-related cognitive decline.

Some studies have suggested that people who eat more fish are less likely to have dementia and stroke . Furthermore, fish is an excellent source of omega-3 fatty acids, which in some studies have been associated with reduced risks of Alzheimer’s disease .

A new study that will be published in the December 2005 issue of the Archives of Neurology found that older people who consumed more fish had significantly slower rates of cognitive decline over six years than did people who ate less fish.

About the Study

This study included 3,718 participants from the Chicago Health and Aging Project, which is an ongoing study of people ages 65 and older (62% black and 38% white) living in Chicago, Illinois.

When the study began and after three and six years, the participants took tests designed to measure their cognition. They also answered a food frequency questionnaire so the researchers could estimate the number of fish meals the participants consumed each week. A fish meal was defined as fish sticks, fish cakes, or a fish sandwich; fresh fish as a main dish; or shrimp, lobster, or crab.

The Findings

Overall, 21% of the participants ate two or more fish meals per week, 36% ate one per week, and 43% ate less than one per week.

The cognition tests showed that, on average, the participants experienced significant cognitive decline over time. But participants who consumed more fish experienced slower cognitive decline. Specifically, eating one fish meal per week was associated with a 10% reduction in cognitive decline, and eating two or more fish meals per week was associated with a 13% reduction in cognitive decline.

While the researchers controlled for a number of factors that may affect cognition, including daily activities, exercise levels, alcohol consumption, and medical history, it is possible that there is some other attribute in people who tend to eat fish that caused the reduced rate of cognitive decline.

How Does This Affect You?

These findings suggest that if you are 65 years old or older, consuming at least one fish meal per week may reduce your rate of cognitive decline by 10% or more. This study could not determine what it is about fish that slows the rate of cognitive decline. It may be that people who eat more fish consume less fat overall, and diets higher in fat have been linked to dementia. Or it may be that fish are abundant in omega-3 fatty acids, which have been associated with reduced rates of cognitive decline. Most likely, it is a combination of these and other factors.

It is becoming apparent that what we eat can have a significant impact on how our brain functions as we age. Another study in the October 2005 issue of the same journal found that people with higher waist-hip ratios (i.e., fat accumulated around their abdomen) experienced changes in their brain structure that have been associated with increased rates of cognitive decline and dementia.

So eating a healthful, well-balanced diet is important for many reasons, including reducing your risk of chronic diseases and obesity, and keeping your mind sharp as you age. Fish is a good source of protein and is low in saturated fat. The American Heart Association recommends incorporating fish into your diet at least twice per week.