The Association between Social Engagement, Loneliness, and Risk of Dementia: A Systematic Review and Meta-Analysis

It has been reported that social engagement may be associated with dementia risk. We searched PubMed, EMBASE, PsycINFO, CINAHL, LILACS, Biomed Central, Scopus, and Web of Science from January 2012 - May 2017, supplemented by extraction from previous reviews. We included cohort and case-control studies examining the association between social engagement or loneliness and dementia risk, pooling data using a random-effects model. Registered: PROSPERO (CRD42017067074). We included 31 cohort and 2 case-control studies comprising 2,370,452 participants. Poor social engagement indices were associated with increased dementia risk, including having a poor social network (RR = 1.59, 95% CI 1.31-1.96; I-2 = 0.00%) and poor social support (RR = 1.28, 95% CI 1.01-1.62; I-2 = 55.51%). In long-term studies (>= 10 years), good social engagement was modestly protective (RR = 0.88, 95% CI 0.80-0.96; I-2 = 0.00%). Loneliness was non-significantly associated with increased risk (RR = 1.38, 95% CI 0.98-1.94; I-2 = 45.32). Our findings encourage interventions targeting social isolation and disengagement for dementia prevention.