We investigated the association between social frailty and Alzheimer's disease (AD) incidence among community-dwelling older adults in Japan. A 53-month follow-up cohort study was conducted in Obu City, Japan. Participants comprised 3,720 community-dwelling older adults (mean age, 71.7 years; 48.4% men). The operational definition of social frailty comprised five items: going out infrequently, rarely visiting friends, feeling unhelpful to friends or family, living alone, and not always talking with someone each day. During follow-up, the cumulative AD incidence risk between socially robust, pre-frail, and frail groups was 4.1%, 5.5%, and 10.7%, respectively. In both crude (HR 2.72, 95% CI 1.90-3.89, p < 0.001) and adjusted Cox proportional hazards models (HR 1.53, 95% CI 1.03-2.28, p = 0.035), social frailty was associated with a significantly higher AD incidence risk. The present study revealed that social frailty is strongly associated with AD incidence among Japanese older adults. Further research should elucidate whether social frailty prevention is effective for decreasing AD risk.
Keywords: Alzheimer’s disease; older adults; social frailty.