Young adults with intellectual and developmental disabilities who participate in Special Olympics are less likely to be diagnosed with depression.

Purpose: People with intellectual and developmental disabilities (IDD) experience high rates of depression. Evidence indicates that physical activity, or participation in a sports club, in a supportive social environment has mental and physical health benefits. Adults with IDD, on average, engage in low levels of physical activity. The purpose of this study was to compare the rates of depression among young adult Special Olympics participants with IDD compared to non-participants with IDD.

Methods: This was a 20-year retrospective cohort study of young adults (19-29 years) with IDD in the province of Ontario, Canada that compared rates of depression among Special Olympics participants (n = 8710) to non-participants (n = 42,393) using administrative health databases housed at ICES (formerly the Institute for Clinical Evaluative Sciences). Using cox proportional hazard models, the crude hazard ratios were calculated for the association between each independent variable and the dependent variable.

Results: After controlling for other variables, the hazard rate for depression among Special Olympics participants compared to the hazard rate for depression among non-participants generated an adjusted hazard ratio of 0.51. Over the 20-year follow-up, the participants were 0.51 times as likely to develop depression as non-participants; this represents a 49% reduction in risk among Special Olympics participants. This result was statistically significant and represents a medium effect size.

Conclusion: Future research is needed on how much of this risk reduction is related to a physiological response to physical activity/exercise, and how much is related to the social connectedness of being part of a group participating in Special Olympics.