Eating fish may keep the brain healthy and reduce the risk of Alzheimer's disease, a new study says. In the study, people who ate baked or broiled fish at least once a week had larger volumes of gray matter in areas of the brain known to be involved in memory and learning. Moreover, people with larger volumes in these areas reduced the risk of developing Alzheimer's disease five-fold over a five year period. People who ate fried fish, on the other hand, did not gain protection against Alzheimer's.
The findings suggest lifestyle choices can ward off Alzheimer's disease, said study researcher Dr. Cyrus Raji, of the University of Pittsburgh School of Medicine. While other research has linked fish consumption to a lower risk of Alzheimer's disease, the study is the first to examine the effect of eating fish on the actual structure of the brain, Raji said. The study was presented today (Nov. 30) at the Radiological Society of North America annual meeting in Chicago.
Gray matter boost
The study involved 260 people who answered questions about their weekly fish consumption, and then had their brains scanned using magnetic resonance imaging (MRI) 10 years later. People with greater volumes of gray matter in brain areas called the hippocampus, posterior cingulated and orbital frontal cortex were less likely than others to have Alzheimer's disease or a type of impaired thinking know as mild cognitive impairment. The link held even after the researchers took into account factors that could affect a person's risk for Alzheimer's, including participants' age, gender and physical activity. Gray matter is important for the brain's ability to function, and decreases in gray matter volume indicate the brain is shrinking, Raji said.
Good for the brain
Fish contains omega-3 fatty acids, which may benefit the brain and protect against Alzheimer's disease, Raji said. Omega-3s improve blood flow to the brain, which in turn delivers more oxygen and nutrients to brain cells. In addition, omega-3s reduce inflammation in the brain, and can protect against the buildup of the amyloid plaques thought to be the cause of Alzheimer's disease, Raji said.
It's possible lifestyle factors other than those accounted for in this study, including socio-economic factors, contributed to the lowered Alzheimer's disease risk seen among some people in the study, the researchers said. In a recent report, the National Institutes of Health reviewed data on risk factors for Alzheimer's disease, and concluded that the evidence available now is insufficient to say that any modifiable risk factor, such as diet, influences the development of Alzheimer's disease.