Adherence to a Mediterranean-style diet can slow the rate of cognitive decline and decrease the risk of dementia: a systematic review

AimThe aim of the present study was to explore the association between a Mediterranean-style diet and cognitive performance, dementia, Alzheimer's disease and associated mortality in ageing populations. MethodsA systematic search of Ovid Medline, Embase and Cinahl plus databases for papers published from September 1970. ResultsTen prospective cohort studies and one cross-sectional study were included in this review. Higher adherence to a Mediterranean-style diet was associated with significantly decreased risks for all-cause dementia, Alzheimer's disease, Alzheimer's disease mortality and infarcts detected by magnetic resonance imaging. Adherence to a Mediterranean-style diet was not, however, consistently associated with tests of cognitive performance and was not associated with the presence of white matter hyper-intensities in the brain. In four of six studies, subjects in the highest tertile for Mediterranean diet adherence had a 28-48% lower risk for development of dementia or Alzheimer's disease than subjects in the lowest tertile. For subjects with Alzheimer's disease, those in the highest tertile of adherence to a Mediterranean-style diet had a 73% lower mortality risk than those in the lowest tertile (fully adjusted hazard ratio 0.27, 95% CIs: 0.10-0.69, P for trend = 0.003). ConclusionsThere is strong evidence for the protective role of a Mediterranean-style diet against cognitive decline and development of Alzheimer's disease. Strategies should now be sought to promote this eating pattern in older Australians. Support for dietitians in implementing this change has potential to reduce the high health-care costs associated with cognitive decline on ageing.