Association of Daily Intellectual Activities With Lower Risk of Incident Dementia Among Older Chinese Adults.

Importance
Associations between late-life participation in intellectual activities and decreased odds of developing dementia have been reported. However, reverse causality and confounding effects due to other health behaviors or problems have not been adequately addressed.

Objective
To examine whether late-life participation in intellectual activities is associated with a lower risk of incident dementia years later, independent of other lifestyle and health-related factors.

Design, Setting, and Participants
A longitudinal observational study was conducted at all Elderly Health Centres of the Department of Health of the Government of Hong Kong among 15 582 community-living Chinese individuals age 65 years or older at baseline who were free of dementia, with baseline evaluations performed January 1 to June 30, 2005, and follow-up assessments performed from January 1, 2006, to December 31, 2012. Statistical analysis was performed from January 1, 2015, to December 31, 2016.

Main Outcomes and Measures
The main outcome was incident dementia as diagnosed by geriatric psychiatrists in accordance with the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, or a Clinical Dementia Rating of 1 to 3. At baseline and follow-up interviews, self-reported information on participation in intellectual activities within 1 month before assessment was collected. Examples of intellectual activities, which were described by a local validated classification system, were reading books, newspapers, or magazines; playing board games, Mahjong, or card games; and betting on horse racing. Other important variables including demographics (age, sex, and educational level), physical and psychiatric comorbidities (cardiovascular risks, depression, visual and hearing impairments, and poor mobility), and lifestyle factors (physical exercise, adequate fruit and vegetable intake, smoking, and recreational and social activities) were also assessed.

Results
Of the 15 582 individuals in the study, 9950 (63.9%) were women, and the median age at baseline was 74 years (interquartile range, 71-77 years). A total of 1349 individuals (8.7%) developed dementia during a median follow-up period of 5.0 years. Multivariable logistic regression analysis showed that the estimated odds ratio for incident dementia was 0.71 (95% CI, 0.60-0.84; P < .001) for those with intellectual activities at baseline, after excluding those who developed dementia within 3 years after baseline and adjusting for health behaviors, physical and psychiatric comorbidities, and sociodemographic factors.

Conclusions and Relevance
Active participation in intellectual activities, even in late life, might help delay or prevent dementia in older adults.