Personality Traits and Social Isolation in Older Adults.

Importance: Personality traits influence social behaviors and health outcomes, yet their role in shaping social isolation among older adults remains insufficiently understood. Social isolation is a modifiable risk factor associated with mortality, cognitive decline, and reduced quality of life; therefore, identifying factors associated with social isolation across the aging population is important. Objective: To examine the association between Big Five personality traits and both baseline social isolation and future risk of social isolation at 3-, 6-, and 9-year follow-up in a nationally representative cohort of older adults. Design, Setting, and Participants: Data for this cohort study were collected from the National Health and Aging Trends Study (NHATS), with personality traits assessed at baseline in NHATS rounds 3 (2013) and 4 (2014), with follow-up assessments of social isolation in 2014, 2017, and 2020. Participants included those who completed the Midlife Development Inventory (MIDI) and were not socially isolated at baseline. Data analysis was performed from 2011 to 2020. Exposure: Personality traits were defined using the Big Five framework, which measures conscientiousness, extraversion, neuroticism, openness, and agreeableness. These traits were assessed using 10 MIDI items. Main Outcomes and Measures: Logistic regression models estimated cross-sectional and longitudinal associations between personality traits and social isolation over a 3-, 6-, and 9-year follow-up, with sequential adjustment for demographic and health-related covariates. Social isolation was defined using a validated 4-item typology. Results: The baseline analytic sample included 2672 community-dwelling individuals (mean [SD] age, 71.1 [10.2] years; 1549 [58.0%] female). Among the 2102 participants who were not socially isolated at baseline (mean [SD] age, 72.9 [9.6] years; 1252 [59.6%] female), higher extraversion (odds ratio [OR], 0.82; 95% CI, 0.73-0.92) and higher agreeableness (OR, 0.70; 95% CI, 0.60-0.82) scores were associated with lower odds of social isolation, whereas conscientiousness was associated with greater isolation risk in fully adjusted models (OR, 1.07; 95% CI, 0.93-1.23). In longitudinal analyses, extraversion had a consistent association with lower odds of social isolation at 3 years (OR, 0.75; 95% CI, 0.63-0.89), independent of demographic and health factors. No personality trait was significantly associated with social isolation at 6 or 9 years after full adjustment, although neuroticism (OR, 1.21; 95% CI, 1.01-1.44) and conscientiousness (OR, 1.37; 95% CI, 1.13-1.67) showed short-term associations in unadjusted models. Conclusions and Relevance: This longitudinal study of community-dwelling older adults found that personality traits, particularly extraversion and agreeableness, were associated with social isolation among older adults, with extraversion emerging as a stronger factor associated with short-term isolation risk. These findings suggest the importance of incorporating personality into strategies aimed at identifying older adults at risk for social isolation and designing tailored interventions to strengthen social connectedness.