Eating at least one serving a week of fish could improve memory function, increase brain volume and stave off Alzheimer's, according to a new study recently presented at the annual meeting of the Radiological Society of North America, Health News reports. Note: that's baked or broiled fish, not Filet-O-Fish.

While previous research has suggested that eating fish may have brain-boosting effects, this study from the University of Pittsburgh Medical Center suggests that consuming fish can battle against the brain shrinkage and cognitive decline associated with Alzheimer's.

“We found higher levels of working memory in people who ate baked or broiled fish on a weekly basis, even when accounting for other factors, such as education, age, gender and physical activity,” lead study author Dr. Cyrus Raji said in a statement.

Researchers tracked 260 adults with normal cognitive function over a decade. Based on questionnaire data, 163 of the participants consumed fish on a weekly basis, with the majority eating fish one to four times per week. The study was the first to use MRI imaging to support its findings.

The brain volume and memory function of each study participant was measured via MRI at both the start and end of the analysis. The findings revealed that those subjects who ate more fish possessed better memory function and larger brain areas, including the posterior cingulated and the orbital frontal cortex, as well as the hippocampus, which is known to shrink in people diagnosed with Alzheimer's.

Raji said that in those with larger brain volume, “The risk for Alzheimer's and mild cognitive impairment went down by fivefold within five years following the brain scans we conducted.” He said that he was “amazed” that the benefit was seen among people who ate fish as little as one to four times a week. “We're talking about just a half serving a day, and that would be a very small lifestyle change that can affect disease risk a long time down the line.”

The results provide support for a study published in the Archives of Neurology last year that found that consumption of a Mediterranean-style diet high in fish, fruit and vegetables was associated with a 38% less likelihood of developing Alzheimer's disease over the following four-year period.

Because no health benefits were linked to consumption of fried fish in the current study, there could be more to the story, such as lifestyle factors or the type of fish consumed.

Experts speculate that omega-3 fatty acids found in fish oils may reduce inflammation of the brain and play a role in brain development and nerve-cell regeneration. Oily fish (such as salmon, herring, trout and sardines–varieties that are not commonly fried) have the highest content of essential omega-3 fatty acids.

Follow Samantha Bonar @samanthabonar.

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