Abstract
BACKGROUND: The association between hobby engagement and risk of dementia reported from a short-term follow-up study for individuals aged ≥65 years may be susceptible to reverse causation. We examined the association between hobby engagement in age of 40-69 years and risk of dementia in a long-term follow-up study among Japanese, including individuals in mid-life, when the majority of individuals have normal cognitive function. METHODS: A total of 22,377 individuals aged 40-69 years completed a self-administered questionnaire in 1993-1994. The participants answered whether they had hobbies according to the three following responses: having no hobbies, having a hobby, and having many hobbies. Follow-up for incident disabling dementia was conducted with long-term care insurance data from 2006 to 2016. RESULTS: During a median of 11.0 years of follow-up, 3,095 participants developed disabling dementia. Adjusting for the demographic, behavioral, and psychosocial factors, the multivariable hazard ratios of incident disabling dementia compared with "having no hobbies" were 0.82 (95% confidence interval [CI], 0.75-0.89) for "having a hobby" and 0.78 (95% CI, 0.67-0.91) for "having many hobbies". The inverse association was similarly observed in both middle (40-64 years) and older ages (65-69 years). For disabling dementia subtypes, hobby engagement was inversely associated with the risk of dementia without a history of stroke (probably non-vascular type dementia), but not with that of post-stroke dementia (probably vascular type dementia). CONCLUSION: Hobby engagement in both mid-life and late life was associated with a lower risk of disabling dementia without a history of stroke.