December 21, 2015

High-Fat Diet Seen Lowering Brain Function

BrainPhoto_475x300Here is something to digest along with your Thanksgiving leftovers: A high-fat diet takes a toll on the brain as well as the waistline.

New research suggests a diet high in saturated fats leads to fewer synapses — the connections the facilitate communication among brain cells — and this could harm the ability to learn and remember. More hopefully, the study says the process can be reversed with a healthier diet.

A team from the Medical College of Georgia at Georgia Regents University fed two groups of mice identical diets, except for the amount of saturated fat they contained. The test animals on the high-fat diet, in which 60 percent of the calories came from fat, showed a reduction in synapses not seen in the mice fed the low-fat diet, which derived 10 percent of its calories from saturated fat.

After 12 weeks, the mice on the high-fat diet had become obese and started to show lower levels of synaptic markers, indicating that synapses were being destroyed, according to the study released for peer review in August and awaiting formal publication in the journal Brain, Behavior and Immunity.

Researchers speculated that the destruction of the synapses came from a misfiring autoimmune response triggered by the chronic inflammation caused when there is too much fat in the body.

The inflammation, long known as a consequence of a fat-laden diet, appears to affect the microglia, which account for about 15 percent of all brain cells and are the primary active immune defense in the central nervous system. The microglia cells typically work to inhibit plaque and infectious agents, but that process went haywire for the mice in the research.

“Normally in the brain, microglia are constantly moving around. They are always moving around their little fingers and processes. What happens in obesity is they stop moving,” said Dr. Alexis M. Stranahan, a Medical College of Georgia neuroscientist who led the study. “They draw in all their processes; they basically just sit there and start eating synapses. When microglia start eating synapses, the mice don’t learn as effectively.”

Mice that remained on the high-fat diet continued to get chubbier and their brains got weaker. The study did, however, offer some positive news: Mice that went from a high-fat to a low-fat diet returned to normal brain functions, even if they didn’t lose all the weight they gained.

Dr. Kate Zhong, Senior Director of Clinical Research and Development for the Cleveland Clinic Lou Ruvo Center for Brain Health, said the findings were exciting but cautioned that since the study was on mice, not humans, more research is needed.

“The results are indicative of the benefits of a low-fat diet, something we have stressed for years as a way to promote brain health and overall good health.”


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