Mediterranean diet and Alzheimer’s disease

Abstract

Alzheimer’s disease (AD), the most common form of dementia, is a progressive neurodegenerative disease with no effective cure. Lifestyle factors, including nutrition and diet, are attracting increasing attention in AD research. It has been suggested that the Mediterranean diet (MeDi) may protect against cognitive decline and dementia. People adhering to a MeDi showed a decrease in the risk of cognitive disorders in several epidemiological studies. While higher adherence to a MeDi was related to a reduced risk of incident cognitive impairment, lower adherence was associated with an increase in the incidence of AD and mild cognitive impairment. However, the majority of published studies on MeDi and AD are observational and cannot answer the question whether the association is causal. Cohort studies with long follow-up periods and large samples suggest an association between adherence to MeDi and a decrease in the risk of cognitive decline and AD. Lower MeDi adherence has been shown to be associated with progressive AD biomarker abnormalities in middle-aged adults. The lower risk of AD associated with the MeDi could be mediated through reduced vascular risk factors and beneficial effects on glucose and lipid metabolism. Certain components of the MeDi, such as its high fruit and vegetable content, relatively low level of carbohydrates and its use of extra-virgin olive oil as the main source of fat, could provide protective effects against cognitive decline, including AD. These findings call for further investigations of the potential of dietary interventions to protect against brain aging and AD. However, other factors of the Mediterranean lifestyle, such as regular physical exercise and strong social networks, may also contribute to the reduced risk of the disease. Long-term randomized controlled trials are needed to establish a causal relationship between MeDi and the prevention or improvement of cognitive decline in AD. At present, it is not possible to prescribe the MeDi as a preventive measure in AD, since knowledge of the type and quantity of individual food components and bioactives required for effective neuroprotection is lacking.