Social Activities and Risk of Dementia in Community-Dwelling Older People: Gender-Specific Findings From a Prospective Cohort Study

OBJECTIVES: This study examines the gender-specific associations between a wide range of social activities and dementia risk. METHODS: A prospective cohort study was conducted involving community-dwelling older Australians (≥70 years) without significant cognitive impairment at enrolment. During the first year of enrolment, we assessed 25 self-reported social activities covering various aspects, including support from relatives and friends, community participation, social interactions with surroundings, and loneliness. Dementia diagnosis followed DSM-IV criteria, adjudicated by an international expert panel. To estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations between social activities and dementia, we performed Cox proportional hazards models, adjusting for age, educational attainment, baseline global cognition, and depressive symptoms. RESULTS: Among 9,936 participants who completed all social activity questionnaires (median [IQR] age: 73.4 [71.6-77.1] years; 47.4% men), dementia was diagnosed in 3.8% of men (n = 181/4,705) and 2.6% of women (n = 138/5,231) over a median 6.4 years (IQR: 5.3-7.6, range: 0.2-10.1) follow-up. Gender-specific relationships emerged: caregiving for a person with illness/disability in women (HR: 0.65, 95% CI: 0.42-0.99), and having ≥9 relatives feeling close to call for help in men (HR: 0.56, 95% CI: 0.33-0.96; reference <9 relatives) were associated with reduced dementia risk. Unexpectedly, in women, having ≥5 friends with whom they felt comfortable discussing private matters were associated with a greater dementia risk (HR: 1.69, 95% CI: 1.10-2.59; reference ≤2 friends). Imputed models further identified that babysitting/childminding was associated with lower dementia risk in men (HR: 0.75, 95% CI: 0.56-0.99). No other social activities showed significant associations with dementia. DISCUSSION: This study provides evidence of social activities influencing dementia risk. Further investigations are required to uncover the mechanisms driving these observed relationships.