Extra-virgin olive oil, a major component of the Mediterranean diet, is rich in cell-protecting antioxidants and known for its multiple health benefits. Previous studies in mice showed that extra-virgin olive oil preserves memory and protects the brain against Alzheimer’s disease. In the new animal study, a team of researchers from Temple University and the Sapienza University of Rome shows that a family of related neurodegenerative diseases called tauopathies — which are characterized by the gradual buildup of an abnormal form of a protein called tau in the brain — can be added to the list. The study is the first to suggest that extra-virgin olive oil can defend against a specific type of mental decline linked to tauopathy known as frontotemporal dementia.

“Extra-virgin olive oil has been a part of the human diet for a very long time and has many benefits for health, for reasons that we do not yet fully understand,” said Professor Domenico Praticò, director of the Alzheimer’s Center at the Lewis Katz School of Medicine at Temple University.

“The realization that extra-virgin olive oil can protect the brain against different forms of dementia gives us an opportunity to learn more about the mechanisms through which it acts to support brain health.”

In a previous work using a mouse model in which animals were destined to develop Alzheimer’s disease, Professor Praticò and colleagues showed that extra-virgin olive oil supplied in the diet protected young mice from memory and learning impairment as they aged.

Most notably, when the researchers looked at brain tissue from mice fed extra-virgin olive oil, they did not see features typical of cognitive decline, particularly amyloid plaques — sticky proteins that gum up communication pathways between neurons in the brain. Rather, the animals’ brains looked normal.

The new study shows that the same is true in the case of mice engineered to develop tauopathy.

In these mice, normal tau protein turns defective and accumulates in the brain, forming harmful tau deposits, also called tangles. Tau deposits, similar to amyloid plaques in Alzheimer’s disease, block neuron communication and thereby impair thinking and memory, resulting in frontotemporal dementia.

Tau mice were put on a diet supplemented with extra-virgin olive oil at a young age, comparable to about age 30 or 40 in humans.

Six months later, when mice were the equivalent of age 60 in humans, tauopathy-prone animals experienced a 60% reduction in damaging tau deposits, compared to littermates that were not fed extra-virgin olive oil.

Animals on extra-virgin olive oil-rich diet also performed better on memory and learning tests than animals deprived of the olive oil.

When the scientists examined brain tissue from extra-virgin olive oil-fed mice, they found that improved brain function was likely facilitated by healthier synapse function, which in turn was associated with greater-than-normal levels of a protein known as complexin-1. Complexin-1 is known to play a critical role in maintaining healthy synapses.

The team now plans to explore what happens when extra-virgin olive oil is fed to older animals that have begun to develop tau deposits and signs of cognitive decline, which more closely reflects the clinical scenario in humans.

“We are particularly interested in knowing whether extra-virgin olive oil can reverse tau damage and ultimately treat tauopathy in older mice,” Professor Praticò said.

The findings were published in the journal Aging Cell.

_____

Elisabetta Lauretti et al. Extra virgin olive oil improves synaptic activity, short‐term plasticity, memory, and neuropathology in a tauopathy model. Aging Cell, published online November 24, 2019; doi: 10.1111/acel.13076