Supplementation and Mitigating Cognitive Decline in Older Adults With or Without Mild Cognitive Impairment or Dementia: A Systematic Review

Abstract

This systematic literature review aims to answer the question of how micronutrients might influence the development and progression of dementia. In the present work, we focused on an overview of an updated review of relevant literature published in the last two decades. This review aims to delineate the relationship between micronutrient supplementation and cognitive decline in older subjects. In carrying out this review, we followed PRISMA, and our literature search was performed on PubMed. This systematic review includes only primary studies that have investigated the efficacy of nutritional interventions for the prevention of dementia and improvement of cognitive function in subjects aged 65 years or older with normal cognition, mild cognitive impairment (MCI), or Alzheimer's disease (AD). A gross heterogeneity of studies forbids the possibility of a direct comparison of the results. A review of the inclusion criteria and restrictions has been conducted to check the validity and reliability of the results. In this review, thirty-three primary studies were included. Results have shown that supplementation with vitamin D, probiotics, and PUFAs would most likely reduce cognitive decline, dementia, or AD compared with vitamins A, B, C, and E, which were seen to be relatively ineffective. Of note, when considering vitamin B supplementation, positive effects were only observed in non-aspirin users having high ω-3 fatty acid (ω-3 FA) plasma levels. In some cases, however, there were genotypic differences in subjects in response to vitamin B supplementation.

Keywords: Alzheimer’s disease; PUFA; aging; cognitive decline; dementia; nutrition; probiotics; supplement; vitamins.

Figure 1

Eligibility criteria for the study of supplementation and mitigating cognitive decline in older adults with or without mild cognitive impairment or dementia: a systematic review. This graph is guided by the PRISMA 2020 flow diagram.

Figure 2

Summary of the major experimental confounders and recommendations.