Association between trajectories of life-course group sports participation and dementia: A 3-year longitudinal study

The evidence for a causal effect of physical activity (PA) on dementia risk remains inconclusive. Group sports participation may impact dementia risk differently compared to PA. This study aimed to examine the association between long-term group sports participation trajectories across the life course and dementia onset among older Japanese adults.

Cohort study.

This cohort study included 8277 adults aged ≥65 years from the Japan Gerontological Evaluation Study. Life-course group sports participation was assessed through self-reported questionnaires, and Group-Based Trajectory Modelling (GBTM) was used to identify participation trajectories. Dementia onset was determined using public long-term care insurance-system registries, and Cox proportional hazards models were employed to assess associations between trajectory groups and dementia onset.

GBTM identified four trajectories: persistently low (n = 5164, 62.4 %), dropout after high school (n = 2150, 26.0 %), dropout after young adulthood (n = 446, 5.4 %), and increase in midlife (n = 517, 6.2 %). During a mean follow-up of 3.2 years, 311 participants developed dementia. After adjusting for confounders, the dropout after young adulthood group had a significantly higher dementia risk than did the persistently low group (hazard ratio, 95 % confidence interval, 1.85, 1.09-3.16). No significant differences were observed between the dropout after high school (1.13, 0.84-1.52) and the increase in midlife (1.36, 0.78-2.39) groups compared to the persistently low group.

The risk of dementia may vary depending on life-course group sports participation patterns. Further studies are needed to establish these findings, including examining specific types of sports and individual PA levels.