Combined effects of social isolation and loneliness on disability incidence in older adults.

Objectives: Relationships among social isolation, loneliness, and disability onset remain unclear. We investigated the distinct patterns of disability development among Japanese older adults who experience social isolation and loneliness.

Design: This study applied a prospective observational approach.

Participants: Data from 4,716 community-dwelling independent older adults were analyzed.

Measurements: The Japanese version of the University of California, Los Angeles Loneliness Scale Version 3 and the Social Isolation Scale were used to measure loneliness and social isolation, respectively. The long-term care insurer conducted monthly follow-ups with participants over two years to determine their care needs. Disability onset was defined as the point at which participants were certified by a care manager as requiring long-term care.

Results: During the follow-up period, 265 participants (5.6 %) required long-term care insurance certification due to disability onset. The incidence of disability in the lonely and not lonely groups was 8.0 % and 4.5 %, respectively. In the socially isolated and not socially isolated groups, it was 7.1 % and 4.4 %, respectively. The Cox proportional hazards regression model revealed a significantly higher risk of disability incidence in the lonely and socially isolated groups. The high-risk group experiencing both loneliness and social isolation exhibited significantly higher hazard ratios than the low-risk group without these symptoms.

Conclusions: The results indicated that older adults experiencing both social isolation and loneliness were at high-risk for future disability incidence. This finding provides insight into the complex interplay between social factors and disability, which can contribute to the development of effective interventions to promote healthy aging and prevent disability.