[Types and number of hobbies and incidence of dementia among older adults: A six-year longitudinal study from the Japan Gerontological Evaluation Study (JAGES)].

Objectives　Dementia prevention is an important issue in the current super-aging society. Previous studies have shown a low risk of dementia in older adults who have hobbies, especially gardening, tourism, and those that are sports-based. However, it is unclear whether the effect of dementia prevention differs according to the specific type and number of hobbies. This study aims to clarify the relationship of dementia onset with the type and number of hobbies practiced by a person.Methods　This prospective cohort study conducted between 2010 and 2016 by the Japan Gerontological Evaluation Study surveyed 56,624 functionally independent individuals aged 65 years and over who had non-missing information on age and gender. A total of 49,705 participants who provided valid answers to the question regarding hobbies, and were followed for 365 days or more, were analyzed. The primary outcome of this study was dementia, which was assessed by the nationally standardized dementia scale proposed by the Ministry of Health, Labour, and Welfare of Japan. Explanatory variables were specific types of hobbies practiced by 5% or more of older adults (males: 14 types and females: 11 types) and the number of hobbies an individual engaged in (0~5 types or more). The covariates were basic characteristics, diseases, health behavior, social support, psychology/cognition, and instrumental activities of daily living. Hazard ratios (HRs) were calculated using the Cox proportional hazards model adjusted for a total of 22 variables.Results　In total, 4,758 patients (9.6%) developed dementia during the follow-up period. The following hobbies were related to a lower risk of developing incident dementia: a) both in males and females, ground golf (HR: males, 0.80; females, 0.80) and travel (males, 0.80; females, 0.76); b) only in males, golf (0.61), use of a personal computer (0.65), fishing (0.81), and photo shooting (0.83); and c) only in females, handicrafts (0.73), and gardening (0.85). A significant trend was observed indicating that the risk of dementia was lower as the number of hobbies increased for both males and females (males, 0.84; females, 0.78).Conclusion　The results of this study suggest that both male and female older adults who engaged in ground golf and travel as a hobby had a lower risk of developing dementia, and the risk decreased as the number of hobbies increased. Providing an environment in which older adults can engage in various hobbies that are associated with less risk of developing dementia, may be an effective measure for preventing dementia.