The Effect of Adherence to the Mediterranean Diet on Late-Life Cognitive Disorders: A Systematic Review

Objectives Although some results are conflicting, numerous investigations have demonstrated that the Mediterranean Diet (MedDiet) has positive effects on brain health. This review intends to provide an update on the scientific evidence regarding the effects of adherence to the MedDiet on late-life cognitive disorders. Design A systematic review was performed. The PubMed and Scopus databases were searched for longitudinal studies and randomized controlled trials (RCTs) published between the databases’ inceptions and May 4, 2020. PRISMA guidelines were followed; the quality of the studies was assessed using version 2 of the Cochrane risk-of-bias tool for the RCTs and the Newcastle-Ottawa Scale for the longitudinal studies. The results are reported descriptively. Settings and Participants Middle-aged and older adults. Measures The review's principal outcomes were cognitive decline, cognitive performance and function, Mild Cognitive Impairment (MCI), Alzheimer's disease (AD), and dementia. Results Forty-five of the 995 articles retrieved from the databases met our criteria. Seven were RCTs and 38 were longitudinal studies. Overall the studies showed that the MedDiet has some protective effects on cognitive decline. As far as cognition domains were concerned, the MedDiet was associated only with improved global cognition. The results were mixed for MCI and AD. There was no evidence that it has a beneficial effect on dementia. Conclusions and Implications The review's analysis confirmed that adherence to the MedDiet is associated with some improvement in cognitive health. The heterogeneity of the scoring systems assessing adherence to the MedDiet and of the modalities evaluating the cognitive outcomes has played no small role in the differences emerging in the results and has hindered efforts to interpret them. Although other interventional studies are warranted to confirm the efficacy of the MedDiet in preventing cognitive disorders, the results show that it can be considered part of a multifactorial approach to improve late-life cognitive function.