Extra-Virgin Olive Oil Protects Against Alzheimer's Disease

A diet enriched with extra-virgin olive oil observed to reduce amyloid plaque and phosphorylated tau in mice.

The Mediterranean Diet has been praised by scientists as a way to improve overall health, while reducing the risk of heart disease and dementia-related conditions.

The authors of a new study published by the Annals of Clinical and Translational Neurology found that extra-virgin olive oil may be protective against cognitive decline.

In the study, the authors found that consumption of the oil protected memory and learning, while also reducing the formation of amyloid-beta plaques and neurofibrillary tangles, which are involved with Alzheimer’s disease.

The investigators also discovered why olive oil is protective against Alzheimer’s disease.

“We found that olive oil reduces brain inflammation but most importantly activates a process known as autophagy," said senior investigator Domenico Praticò, MD.

Autophagy occurs when cells break down and clean up intracellular debris and toxins, including amyloid plaques and tau tangles, according to the study.

"Brain cells from mice fed diets enriched with extra-virgin olive oil had higher levels of autophagy and reduced levels of amyloid plaques and phosphorylated tau," Dr Praticò said.

Phosphorylated tau is the cause of neurofibrillary tangles, which contribute to nerve cell dysfunction in the brain related to Alzheimer’s disease.

Previous studies suggest that the high prevalence of extra-virgin olive oil in the diets of individuals living in the Mediterranean is linked to health benefits of the 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," Dr Praticò said.

In the study, the authors explored the link between olive oil and Alzheimer’s disease in mice that were predisposed to develop memory impairment, amyloid plaques, and neurofibrillary tangles.

The mice either received a regular diet or one enriched with extra-virgin olive oil. The enriched diet group was introduced to olive oil prior to the age of 6 months, which is before the onset of symptoms of Alzheimer’s disease emerge, according to the study.

At 9 months and 12 months, the authors noted that the mice receiving the diet enriched with extra-virgin olive oil performed better on tests related to working memory, spatial memory, and learning, according to the study.

Brain tissue examination also revealed significant differences in the nerve cells of both groups of mice.

"One thing that stood out immediately was synaptic integrity," Dr Praticò said.

The authors discovered that the integrity of the synapses was protected among animals eating the extra-virgin olive oil diet. Additionally, the brain cells from this group were observed to have increased autophagy activation, which reduced the development of amyloid plaques and phosphorylated tau, according to the study.

"This is an exciting finding for us," Dr 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 of researchers plan to explore the effects of the extra-virgin olive oil in older mice who have already developed plaques and tangles, according to the study.

"Usually when a patient sees a doctor for suspected symptoms of dementia, the disease is already present," Dr Praticò said. "We want to know whether olive oil added at a later time point in the diet can stop or reverse the disease."