Title: The effects of Mediterranean Diet on cognitive function and dementia: Systematic review of the evidence
Abstract: Introduction: There is a growing body of evidence suggesting that adherence to the Mediterranean Diet (MD) may protect against cognitive decline and dementia although the evidence is still inconsistent. Aim: The aim of this systematic review is to update the current knowledge on the effects of MD on cognitive function and/or cognitive impairment (CI) and/or Alzheimer’s disease (AD) and/or all-type dementia. Materials and methods: Five databases were searched: PubMed, CINAHL, CENTRAL and PsychINFO (date 1806 to 25th May, 2015), using pre-specified criteria. Human studies, published in English, without any restriction in study type, population assessed, intervention period, follow-up time, or publication date, examining the association between adherence to the MD and cognitive function or dementia symptoms (as measured by cognitive function tests) were included. Only primary publication types were included. Results: 32 studies, including 5 Randomized Controlled Trials (RCTs) and 27 observational studies, met the inclusion criteria. The majority of studies showed that MD improved cognitive function and/or decreased risk of CI and/or decreased risk of dementia/AD. Three studies found no correlation between MD and AD, 3 found no association between MD and CI and 5 found no association between MD and cognitive function. There was large heterogeneity and studies differed with regards to quality. Conclusion: Overall, the existing evidence, stemming mostly from epidemiological studies, suggests that MD improves cognitive function and delays the onset of dementia. However, more RCTs are required to establish a causational relationship.