Beneficial Effects of Olive Oil and the Mediterranean Diet on Alzheimer's Disease and Vascular Dementia: A Review.

Background and Objectives: During the past 25 years, a significant body of research has been conducted reporting on the salutary effects of the Mediterranean diet and extra-virgin olive oil, one of its main components. The initial studies were epidemiological observations on populations with very low mortality rates due to significant reductions in myocardial infarction fatalities. Population-based studies demonstrated that the Mediterranean diet with olive oil consumption is associated with a lower prevalence of cardiovascular and cerebrovascular disease, obesity, arthritis, and cancer. Materials and Methods: In this narrative review, we present recent studies on the effects of extra-virgin olive oil and the Mediterranean diet-compared with various other diets-on several vascular risk factors, including hypertension, hyperlipidemia, type 2 diabetes mellitus, and obesity, as well as their impact on cognitive decline and dementia. Results: This diet has been shown to improve cognitive function in patients with mild cognitive impairment, Alzheimer's disease, vascular cognitive impairment, and vascular dementia. The main mechanisms responsible for cognitive improvement include control of arterial hypertension by reducing systolic and diastolic blood pressure, lowering triglycerides and low-density lipoprotein cholesterol and increasing high-density lipoprotein cholesterol, along with improvement in fasting glucose, insulin levels, and hemoglobin A1c in subjects with type 2 diabetes mellitus, as well as lowering body mass index and obesity. Conclusions: The Mediterranean diet and olive oil induce-along with prevention of cardiovascular disease and stroke-a significant improvement of vascular risk factors, slowing the progression of both vascular dementia and Alzheimer's disease. There is a need for additional placebo-controlled clinical trials to confirm the supportive nutritional role of extra-virgin olive oil in age-associated cognitive decline in the elderly.