Bidirectional association between mental health and physical activity in older adults: Whitehall II prospective cohort study

OBJECTIVE: To investigate longitudinal and bidirectional associations between mental health and physical activity from midlife into old age. METHODS: Analysis was based on data from 6909 participants (aged 45 to 69 in 1997/99) from the Whitehall II cohort in the UK. Latent growth curve analysis examined possible bidirectional associations between the SF-36 Mental Component Summary and weekly physical activity measured at three time-points over ten years. RESULTS: Mental health and physical activity were associated at baseline (β=0.17, 95% CI 0.13, 0.21) and associations persisted into old age. In the latent growth curve model, both mental health and physical activity increased and their rates of change 'moved together' over time (β=0.24, 95% CI 0.11, 0.37). Relatively high baseline levels of either variable were associated with slightly slower increases in the other outcome (β=-0.02, 95% CI -0.03, -0.01; β=-0.07, 95% CI -0.11, -0.13), which are thought to reflect regression to the mean. However, those who started high on either variable remained the most advantaged at end of follow-up. CONCLUSIONS: From midlife to old age, greater physical activity is associated with better mental health and vice versa. These findings suggest persistent longitudinal and bidirectional associations between physical activity and mental health.