Background and Objective:
The increasing number of people with Mild Cognitive Impairment (MCI) and dementia represents a relevant public health problem. For this reason, there is interest in the assessment of factors affecting disease risk, in order to implement effective prevention strategies and promote a healthy lifestyle. In particular, diet as a determinant of cognitive impairment and dementia represents an important field of research, and many studies focused on the effects of plant-based, vegetarian or vegan diets on cognitive functions and dementia risk. The aim of this systematic review is to assess whether a plant-based or a ‘strict’ vegetarian diet is protective or detrimental towards cognitive functions.

Methods:
The protocol of this systematic review and meta-analysis has been submitted to PROSPERO. The literature search has been conducted on 4 different databases: PubMed, Web of Science, Embase and Cochrane library. We used MeSH terms and keywords related to “plant-based diet”, “vegetarian diet”, “Mild Cognitive Impairment”, “dementia” and “memory impairment”. We found 2 additional articles through citation chasing techniques. We defined the following inclusion criteria according to the PICOS statement: adult population, adherence to plant-based, vegetarian or vegan diets, assessment of cognitive functions through dementia risk or cognitive decline at increasing adherence to different dietary patterns, and both observational studies (cohort, cross-sectional or case-control) and randomized clinical controlled trials. We will also perform a dose-response meta-analysis whenever possible.

Results:
In the preliminary literature search, we found a total of 1537 articles (including 2 studies added through citations), 255 of which were duplicates. After duplicate removal, the abstract and the full-text of 1282 articles were screened, leading to the exclusion of 1263 of them. Nineteen studies met our inclusion criteria and could be included in the systematic review.

Conclusions:
The study is currently ongoing and its results will be presented at the Congress.