Eating baked or broiled
fish once a week is good for the brain, regardless of how much omega-3 fatty
acid it contains, according to researchers at the University of Pittsburgh
School of Medicine. The findings, published online recently in the American
Journal of Preventive Medicine, add to growing evidence that lifestyle
factors contribute to brain health later in life.
Scientists estimate that
more than 80 million people will have dementia by 2040, which could become a
substantial burden to families and drive up health care costs, noted senior
investigator James T. Becker, Ph.D., professor of psychiatry, Pitt School of
Medicine. Some studies have predicted that lifestyle changes such as a
reduction in rates of physical inactivity, smoking and obesity could lead to
fewer cases of Alzheimer's disease and other conditions of cognitive impairment
in the elderly. The anti-oxidant effect of omega-3 fatty acids, which are found
in high amounts in fish, seeds and nuts, and certain oils, also have been
associated with improved health, particularly brain health.
"Our study shows
that people who ate a diet that included baked or broiled, but not fried, fish
have larger brain volumes in regions associated with memory and
cognition," Dr. Becker said. "We did not find a relationship between
omega-3 levels and these brain changes, which surprised us a little. It led us
to conclude that we were tapping into a more general set of lifestyle factors
that were affecting brain health of which diet is just one part."
Lead investigator Cyrus
Raji, M.D., Ph.D., who now is in radiology residency training at UCLA, and the
research team analyzed data from 260 people who provided information on their
dietary intake, had high-resolution brain MRI scans, and were cognitively
normal at two time points during their participation in the Cardiovascular
Health Study (CHS), a 10-year multicenter effort that began in 1989 to identify
risk factors for heart disease in people over 65.
"The subset of CHS
participants answered questionnaires about their eating habits, such as how
much fish did they eat and how was it prepared," Dr. Raji said.
"Baked or broiled fish contains higher levels of omega-3s than fried fish
because the fatty acids are destroyed in the high heat of frying, so we took
that into consideration when we examined their brain scans."
People who ate baked or
broiled fish at least once a week had greater grey matter brain volumes in
areas of the brain responsible for memory (4.3 percent) and cognition (14
percent) and were more likely to have a college education than those who didn't
eat fish regularly, the researchers found. But no association was found between
the brain differences and blood levels of omega-3s.
"This suggests that
lifestyle factors, in this case eating fish, rather than biological factors
contribute to structural changes in the brain," Dr. Becker noted. "A
confluence of lifestyle factors likely are responsible for better brain health,
and this reserve might prevent or delay cognitive problems that can develop
later in life."
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