More fish, less Alzheimer disease

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Scientists at the Lipid Metabolism Laboratory at Tufts generally focus on heart disease. But they are poised to publish findings in the very near future that suggest the same two fish meals a week that the American Heart Association recommends for staving off cardiovascular ills might also help protect against dementia, Alzheimer disease included. The researchers, led by lab chief Ernst Schaefer, MD, made their discovery while going over data from the Framingham Dementia Study, which grew out of the now famous Framingham Heart Study.

The Framingham Heart Study began in 1950 with some 3,000 people. In the mid 1980s, when there were roughly 1,200 of the original subjects still alive with an average age of about 75, Dr. Schaefer and his team began looking at a type of fish-derived fatty acid in their blood plasma known as DHA. They then followed those subjects for almost a decade, seeing who ended up with Alzheimer disease and other age-related types of dementia and comparing the concentration of DHA in their blood to the DHA in the blood of people who did not develop dementia.

It turns out that those with the highest DHA levels were only about half as likely to develop dementia by the time they were in their 80s as those with the lowest levels. Translating those high levels to eating patterns, Dr. Schaefer suggests eating three servings of fish a week. One and a half to two weekly fish servings was also associated with a reduced risk for dementia in later years, Dr. Schaefer reports. "The results were just not as dramatic for those amounts."

This is not the first time eating more fish has been linked with a reduced chance of developing age-related dementia (about two thirds of which tends to be Alzheimer disease). Last year, for instance, investigators in Chicago found that older people at particularly high risk for dementia who ate fish at least once a week reduced their chances of falling victim to Alzheimer disease and similar conditions by 60 percent.

Exactly how the oils, or fats, in fish might protect from dementia isn't known with certainty yet. But it is known that while only 3 to 4 percent of fatty acids in the blood plasma are DHA, the proportion is closer to 40 percent in the brain. Those fatty acids are present in cell membranes, which surround each brain cell. When they contain DHA, it makes the membranes more fluid than they would be with other fatty acids, which might make it easier for messages to get from one brain cell to another, improving memory and cognition.

Mechanisms remain to be worked out, Dr. Schaefer says, and "our observations need to be confirmed by trials in which we give some people fish or fish oil and others a placebo and see what happens down the line." But in the meantime, he says, "we're supposed to be eating more fish than Americans generally do, anyway, so it certainly can't hurt the brain and may only help to have fish for lunch or dinner two to three times a week."

"It can't hurt the brain and may only help to have fish for lunch or dinner to two to three times a week."

PHOTO (BLACK & WHITE): Ernst Schaefer, MD, Chief, Lipid Metabolism, Laboratory

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