Bi-directional associations between healthy lifestyles and mood disorders in young adults: The Childhood Determinants of Adult Health Study.

BACKGROUND Healthy lifestyles prevent cardiovascular disease and are increasingly recognized in relation to mental health but longitudinal studies are limited. We examined bi-directional associations between mood disorders and healthy lifestyles in a cohort followed for 5 years. METHOD Participants were aged 26-36 years at baseline (2004-2006) and 31-41 years at follow-up (2009-2011). At follow-up, lifetime mood disorders (depression or dysthymia) were retrospectively diagnosed with the Composite International Diagnostic Interview. A five-item lifestyle score (comprising body mass index, non-smoking, alcohol consumption, leisure time physical activity and healthy diet) was measured at both time points. Linear and log multinomial regression determined if mood disorder before baseline predicted changes in lifestyle (n = 1041). Log binomial regression estimated whether lifestyle at baseline predicted new episodes of mood disorder (n = 1233). Covariates included age, sex, socio-economic position, parental and marital status, social support, major life events, cardiovascular disease history, and self-rated physical and mental health. RESULTS A history of mood disorder before baseline predicted unfavourable trajectories of lifestyle over follow-up, including somewhat lower risk of improvement [relative risk (RR) 0.76, 95% confidence interval (CI) 0.56-1.03] and greater risk of worsening (RR 1.46, 95% CI 0.99-2.15) of lifestyle independent of confounding factors. Higher lifestyle scores at baseline were associated with a 22% (RR 0.76, 95% CI 0.61-0.95) reduced risk of first episodes of mood disorder, independent of confounding factors. CONCLUSIONS Healthy lifestyles and mood disorders are closely related. Our results suggest that healthy lifestyles may not only reduce cardiovascular disease but also promote mental health.