Cognitive Function and Subjective Well-Being in Japanese Community-Dwelling Older Adults: A Cross-Sectional Study

Background: The relationship between mild cognitive impairment (MCI) and subjective well-being remains poorly understood. We examined associations between cognitive function and well-being domains in community-dwelling older Japanese adults with and without MCI. Subjects and Methods: A cross-sectional analysis of 710 community-dwelling Japanese adults aged 65–75 years was carried out. Well-being was measured using the Philadelphia Geriatric Center Morale Scale (PGCMS score ≥ 13 indicates high well-being), comprising agitation, attitude toward aging, and lonely dissatisfaction subscales. MCI was defined as a Montreal Cognitive Assessment (MoCA) score of 18–25. Multivariable logistic regression examined potential associations between socio-demographic and health factors. Results: Among the participants (mean age 70.0 ± 2.5 years, 49% women), 423 (59.6%) had MCI. The MCI status was not associated with overall well-being (OR 1.06, 95% CI: 0.72–1.57, p = 0.77). However, within the MCI group, each 1-point increase in the MoCA score was associated with lower agitation (OR 1.21, 95% CI: 1.04–1.41) but higher lonely dissatisfaction (OR 0.83, 95% CI: 0.70–0.98, p = 0.02). No associations were observed in the non-MCI group. Conclusions: Cognitive function shows domain-specific rather than global associations with well-being in individuals with MCI.