Associations of meeting the physical activity guidelines with anxiety and depression

This dissertation investigated the association of meeting the World Health Organization (WHO) 2010 physical activity (PA) recommendations with depression, anxiety, and generalised anxiety disorder (GAD). Two meta-analyses of prospective cohort studies showed that engaging in physical activity is associated (OR, 95%CI) with 27%, 18%, 18%, and 27% lower odds of depression (0.73, 0.70-0.76), anxiety symptoms (0.82, 0.77- 0.87), any diagnosed anxiety disorder (0.82, 0.77-0.87), and diagnosed general anxiety disorder (0.73, 0.70-0.76), respectively. However, both reviews highlighted a dearth of evidence that examined (1) the association of meeting WHO recommendations with the onset of depression, anxiety, and GAD, and (2) whether stronger associations are observed with increased doses of physical activity. Two cross-sectional studies of 7,000- 10,000 adults from the Mitchelstown Cohort Study and The Irish Longitudinal Study on Ageing (TILDA) found that meeting WHO recommendations was significantly, inversely associated with anxiety (0.86, 0.76-0.98) and depression (0.56, 0.47-0.65). Stronger associations with increased physical activity dose were observed for depression symptoms but not anxiety. Three prospective cohort studies of approximately 3,000- 4,500 adults from TILDA found that meeting WHO recommendations was significantly associated with lower odds of GAD (0.43, 0.19-0.99), while non-significant associations were observed with depression (0.77, 0.58-1.04) and anxiety (0.94, 0.63-1.40). Increased physical activity dose was associated with lower odds of developing GAD, but no dose response was apparent for depression or anxiety. Overall, the findings of this dissertation support the benefits of meeting physical activity recommendations for depression, anxiety, and GAD.