Alzheimer's: How Extra Virgin Olive Oil Prevents Brain Plaques and Preserves Memory

Report finds a third of dementia cases can be prevented by lifestyle factors. AFP/Getty Images

Extra virgin olive oil is the key ingredient of the Mediterranean diet that protects the brain from Alzheimer's disease and cognitive decline, scientists have discovered.

The health benefits of the Mediterranean diet—rich in plant-based foods, olive oil and fish—have long been known. It reduces the risk of heart disease and stroke, and leads to a lower risk of dementia.

A team of scientists from Temple University, Pennsylvania, has found what in the diet protects the brain from Alzheimer's—and how this key ingredient works to prevent cognitive decline and preserve memories.

Previous research had already linked extra virgin olive oil to many of the health benefits of the Mediterranean diet. "The thinking is that extra-virgin olive oil is better than fruits and vegetables alone, and as a monounsaturated vegetable fat, it is healthier than saturated animal fats," senior investigator Domenico Praticò said in a statement.

Published in the Annals of Clinical and Translational Neurology on Wednesday, researchers investigated the relationship of extra virgin olive oil and dementia using a mouse model. (The animals used develop key characteristics of Alzheimer's, including memory impairment and the build-up of amyloid-beta plaques in the brain.)

Animals were divided into two groups; one received a diet rich in extra virgin olive oil and the other did not. The olive oil was introduced at six months of age, before the mouse Alzheimer's had set in.

By nine and 12 months, the olive oil mice were performing far better on cognitive tests that evaluate memory and learning abilities. Later studies of their brain tissues showed stark differences between the two groups. The mice that had been fed olive oil had lower levels of amyloid plaques and there were big differences in nerve cell appearance and function.

The connections between the neurons—the synapses—were found to be better preserved in the olive oil group than the control, and there was also an increase in nerve cell autophagy activation. The activation of autophagy is the important discovery—since this is the process that helps clear debris and toxins, including amyloid plaques, from the brain.

At present, scientists believe the reduction in autophagy is involved at the onset of Alzheimer's—so finding a mechanism that prevents it could help develop therapies to treat or even reverse the disease.

"This is an exciting finding for us," Praticò said. "Thanks to the autophagy activation, memory and synaptic integrity were preserved, and the pathological effects in animals otherwise destined to develop Alzheimer's disease were significantly reduced. This is a very important discovery, since we suspect that a reduction in autophagy marks the beginning of Alzheimer's disease."

The team now plans to give 12-month-old Alzheimer's mice (which have already developed plaques) extra virgin olive oil to see if it can stop or reverse the disease. "Our studies provide mechanistic support to the positive cross-sectional and longitudinal data on this component of the Mediterranean diet, and most importantly the biological rationale to the novel hypothesis that extra virgin olive oil could be considered as a viable therapeutic opportunity for preventing or halting Alzheimer's disease," they conclude.