Eating fish tied to dramatic drop in Alzheimer's risk

(CBS) Maybe mom was right about fish being brain food. New research shows that people who eat fish regularly are three to five times less likely to develop Alzheimer's disease or a related condition known as mild cognitive impairment (MCI).

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"This is the first study to establish a direct relationship between fish consumption, brain structure and Alzheimer's risk," study author Dr. Cyrus Raji of the University of Pittsburgh Medical Center said in a written statement.

Dr. Raji and his colleagues scanned the brains of 260 healthy adults, including 163 who said they consumed fish at least once a week. After controlling for age, gender, race, physical activity, and other factors, the researchers found that the fish eaters were less likely to have shrinkage of their gray matter. That's a component of the brain involved in memory, emotions, and other high-level functions.

Decreases in the amount of gray matter indicate that individual brain cells (neurons) are shrinking - and Dr. Raji said regular fish consumption makes neurons in gray matter "larger and healther." But he stressed that he was talking only about baked and broiled fish. Eating fried fish was not shown to boost brain volume or protect against cognitive decline.

Why would eating fish protect the brain? Dr. Raji said it's likely because fish contains high levels of omega-3 fatty acids, which are known to reduce inflammation and have other physiological benefits. But he pointed out that fish also contains high levels of selenium, another substance known to have benefits for the brain.

The study was scheduled to be presented in Chicago on Wednesday at the annual meeting of the Radiological Society of North America.

The Alzheimer's Association estimates that 5.4 million people have Alzheimer's disease. That's roughly one in eight Americans age 65 or older.

The association has more on Alzheimer's disease.