Social interaction and functional status among community-dwelling older adults in Japan: a longitudinal study during the coronavirus disease 2019 pandemic

Introduction Previous studies have shown that social relationships positively contribute to functional status. However, studies comparing the influence under changing social circumstances are still limited. Consequently, this study investigated how social interaction influenced long-term functional status among older Japanese adults before and during the COVID-19 pandemic. Methods A two-wave longitudinal cohort design was used to compare pre-pandemic (2017–2020) and post-pandemic (2020–2023) cohorts. Data were obtained from the Community Empowerment and Care study in T-Village, Aichi Prefecture, Japan. Social interaction was assessed using the Index of Social Interaction (ISI) and functional status was measured based on long-term care needs. Logistic regression analyzed predictors of functional health over 3 years, controlling for demographic and life-style covariates. Results Social interaction declined during the pandemic. Higher ISI scores, particularly for social curiosity and adaptability, predicted better functional outcomes in both cohorts. Interaction with non-family members and willingness to use new technology were strong protective factors. Discussion Promoting meaningful social engagement and behavioral adaptability may help preserve functional independence in aging populations, especially during periods of social disruption.