Researchers at the University of Louisiana, Monroe, found that oleocanthal, a component of olive oil, can protect nerve cells from the kind of damage that occurs in the neurodegenerative disease.
Alzheimer's disease (AD) affects about 30 million people worldwide, but the prevalence is lower in Mediterranean countries.
Scientists once attributed it to the high concentration of healthful monounsaturated fats in olive oil - consumed in large amounts in the Mediterranean diet.
Amal Kaddoumi and colleagues tracked the effects of oleocanthal in the brains and cultured brain cells of laboratory mice.
In both instances, oleocanthal showed a consistent pattern in which it boosted production of two proteins and key enzymes believed to be critical in removing beta-amyloid from the brain.
"Extra-virgin olive oil-derived oleocanthal associated with the consumption of Mediterranean diet has the potential to reduce the risk of AD or related neurodegenerative dementias," authors concluded.