Public libraries and functional disability: A cohort study of Japanese older adults.

This study examined the association between the presence of public libraries and functional disability risk among community-dwelling older adults. We studied 73,138 participants aged 65 years or older in 19 Japanese municipalities using data from the Japan Gerontological Evaluation Study. They were physically and cognitively independent at baseline and followed up between 2013 and 2021 (mean follow-up: 7.3 years). The onset of functional disability was ascertained by linking participants to the public registries of long-term care insurance. The exposures were the number of library books and that of libraries per population in each municipality. During the study period, we observed 16,336 cases (22.3%) of functional disability onset. Our Cox proportional hazards model revealed that the number of library books (hazard ratio [HR] = 0.96, 95% confidence interval [CI]: 0.95-0.97) and that of libraries (HR = 0.52, 95% CI: 0.28-1.00) were associated with the onset of functional disability. The association was consistent even after adjusting for individuals' reading habits and other potential confounders, which suggested the contextual effect of public libraries on older adults' functional ability. Additionally, the magnitude of association was larger for the younger, women, and people with reading habits than their counterparts. Building new libraries and increasing the number of library books in a community may contribute to lowering the functional disability risk among older adults.