Cognitive leisure and dementia risk: evidence beyond reverse causation

BACKGROUND: Engagement in cognitive leisure activities (CLA) may reduce the risk of dementia, but findings are often challenged by reverse causation and unmeasured cognitive reserve. OBJECTIVE: To examine the association between CLA and incident dementia whilst accounting for reverse causation and lifelong cognitive enrichment. DESIGN: Prospective cohort study with a 12-year follow-up, including a 7-year exposure-outcome time lag. SETTING: Community-dwelling older adults from the three-city study conducted in France. SUBJECTS: A total of 3326 participants aged 65 and older, free of dementia at baseline and during the time-lag period. METHODS: At baseline, participants reported frequency of engagement in five cognitively stimulating activities. A global CLA score was calculated and categorised into low, moderate, and high engagement. Incident dementia and Alzheimer's disease (AD) were ascertained during the 5-year follow-up. Delayed-entry Cox models with age as the time scale were used, adjusting for socio-demographic, health-related, and genetic factors including APOE ε4 and past occupational grade. RESULTS: Compared to low CLA engagement, moderate and high engagement were associated with lower risk of dementia (hazard ratios [HR] = 0.50 [95% CI: 0.33-0.76] and 0.53 [0.35-0.80]) and AD (HR = 0.35 [0.20-0.59] and 0.45 [0.28-0.73]). Frequent engagement in crosswords and artistic activities showed the strongest independent associations with reduced dementia risk. CONCLUSIONS: CLA in late life is associated with lower dementia risk, beyond the influence of cognitive reserve and reverse causation. Promoting such activities may be a valuable component of dementia prevention strategies in older adults.