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Published on Leave a comment on Seafood, DHA Levels, and the Aging Brain

 Eating several servings of seafood (especially fish) weekly has beneficial health effects throughout life, and now research finds another benefit in older adults. Seafood contains both EPA and DHA, which are two types of omega-3 fatty acids. DHA or docosahexanoic acid has "neuroprotective qualities" and is found in both the gray and white matter of the brain. Higher DHA levels (measured in the blood) was associated with better memory, less brain atrophy (better brain volume), and fewer amyloid plaques (which are associated with Alzheimer's) in cognitively healthy older adults. From Medscape:

Higher Serum DHA Linked to Less Amyloid, Better Memory

New research supports neuroprotectant effects of docosahexaenoic acid (DHA) in the aging brain. In a small cross-sectional study of cognitively healthy older adults, higher serum DHA levels were associated with less cerebral amyloidosis, better memory scores, and less regional brain atrophy.

"The interesting finding was the association of low serum DHA levels with cerebral amyloidosis (amyloid plaques) in older adults without evidence of dementia," Hussein N. Yassine, MD, Department of Medicine, University of Southern California, Los Angeles, told Medscape Medical News. "This association was predominantly driven by persons at the lowest quartile of serum DHA levels who likely have limited intake of seafood." "This study adds to the existing evidence on the benefit of seafood consumption on [Alzheimer's disease] AD risk factors," Dr Yassine added.

The study was published online August 8 in JAMA Neurology. In a linked editorial, Joseph F. Quinn, MD, Department of Neurology, Oregon Health and Science University, Portland, notes that DHA is "the most abundant polyunsaturated fatty acid in the brain, playing an important structural role in synapses while also modulating a number of signaling pathways. "Brain DHA levels are also modulated by dietary intake, so it is plausible for dietary DHA to alter brain concentrations and affect downstream targets including brain pathology and function."

Dr Yassine and colleagues assessed serum DHA levels, measures of amyloid burden based on positron emission tomography with Pittsburgh compound B, brain volume, and neuropsychological test scores in 61 adults without dementia in the Aging Brain Study.

They found that serum DHA levels (percentage of total fatty acids) were 23% lower in those with cerebral amyloidosis relative to those without. Serum DHA levels were inversely correlated with brain amyloid load, independent of age, sex, years of education, and apolipoprotein E genotype. They also noted a positive correlation between serum DHA levels and brain volume in several subregions affected by AD, in particular the left subiculum and the left entorhinal volumes.

Clinically, there was a significant association between serum DHA levels and nonverbal memory. This association persisted after adjustment for age but not after adjustment for apolipoprotein E genotype. Serum DHA levels were not associated with measures of global cognition, executive function, or verbal memory scores.

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Another study providing evidence that the Mediterranean diet is good for the brain. In elderly dementia-free adults (mean age 80 years) - those that generally followed a Mediterranean diet (higher adherence) had a larger brain volume than those not following the Mediterranean diet, as well as more total gray and white matter volume.The difference between the groups is equal to about 5 years of aging.

Having "higher adherence to the Mediterranean diet" in the study meant higher consumption of healthy foods or lower consumption of unhealthy foods. The Mediterranean diet stresses a  high intake of vegetables, legumes, fruits, whole grains, fish, olive oil, and low intake of saturated fatty acids, dairy products, meat, and poultry; and mild to moderate amounts of alcohol. Specifically: Higher fish intake (at least 3 to 5 oz. weekly) and lower meat intake (no more than 3.5 oz. daily) correlated with greater total gray matter volume. Higher fish intake was also associated with "greater mean cortical thickness". From Medical Xpress:

Mediterranean diet may keep your mind healthier in old age

In news that sounds a bit like it came straight from a sci-fi thriller, researchers say that eating too much meat might shrink your brain. On the flip sid e, however, eating healthy foods from the so-called Mediterranean diet may help your brain stay in good shape as you get older, the new study suggests. The researchers said that people over 65 who ate more fish, vegetables, fruit, grains and olive oil had a larger brain volume than a similar group who didn't follow a Mediterranean diet.

"It was encouraging to see that the more you adhere to this Mediterranean diet, the more protection you get against brain atrophy [shrinkage]," said study author Yian Gu, an assistant professor of neuropsychology at Columbia University in New York City. .... But Gu noted that her study's observational findings cannot prove a definitive cause-and-effect relationship between diet and brain volume. The study was only designed to find an association.

Previous research has linked the Mediterranean diet to a lower risk of Alzheimer's disease, the study said. The diet stresses the consumption of vegetables, legumes (beans, peas and lentils), fruits, cereals, fish and monounsaturated fats such as olive oil, the study authors said. The eating plan also includes a low intake of meat, poultry, saturated fats and dairy products, as well as mild to moderate amounts of alcohol, according to the researchers.

For the study, Gu and her colleagues split 674 adults into two groups based on how closely their diets aligned with the Mediterranean diet. Their average age was 80 years. All participants underwent MRI scans of their brains to measure total brain volume and thickness. They also completed questionnaires about their food choices and eating patterns.

The researchers found that brain volumes of those who didn't follow a Mediterranean diet were smaller than those who did. The difference was minor in overall size—equated to about five years of aging, the study authors said. But, more specifically, the investigators found that eating more fish and less meat was associated with even less brain shrinkage. Using the study findings, Gu contended that eating at least 3 to 5 ounces of fish weekly, or no more than 3.5 ounces of meat each day, could protect the brain from shrinkage. She acknowledged that study participants may have inaccurately recalled their food consumption habits in the questionnaires used.