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

Objectives This study examines 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 was 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 a 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.