Association between multimorbidity and the risk of dementia: A systematic review and meta-analysis.

BACKGROUND

Multimorbidity has become increasingly prevalent and poses challenges in managing cognitive function. This study aimed to (1) systematically review and perform a meta-analysis to understand the relationship between multimorbidity and the risk of dementia and (2) examine the impact of different multimorbidity patterns on this relationship.

METHOD

A systematic review was conducted using PubMed, Embase, PsychINFO, CINAHL, and Cochrane Central to gather studies published up to December 16, 2023. For the meta-analysis, studies with consistent study designs, multimorbidity definitions, and stages of dementia were included. Heterogeneity was assessed using the I statistic, and Egger's and Begg's tests were used to evaluate publication bias.

RESULTS

Of the 12,074 studies identified, 11 were deemed suitable for systematic review, and eight were included in the meta-analysis. Meta-analysis of the longitudinal studies revealed that baseline multimorbidity was significantly associated with an increased risk of dementia compared with individuals without multimorbidity (HR: 1.34, 95 % CI: 1.08-1.68). Meta-analysis of the cross-sectional studies indicated that multimorbidity was significantly associated with a higher risk of being in the prodromal stages of dementia than in individuals without multimorbidity (OR: 1.32, 95 % CI: 1.16-1.51). The risk of dementia varied according to diverse multimorbidity patterns, and the cardiovascular-metabolic condition-related patterns were the most common and associated with high dementia risk.

CONCLUSIONS

Our findings provide quantitative evidence of a significant association between multimorbidity and the risk of dementia. To develop effective dementia prevention strategies, an in-depth understanding of specific multimorbidity patterns is invaluable for managing cognitive function.