Income inequality and comorbid overweight/obesity and depression among a large sample of Canadian secondary school students: The mediator effect of social cohesion

Background

Comorbid overweight/obesity (OWO) and depression is emerging as a public health problem among adolescents. Income inequality is a structural determinant of health that independently increases the risk for both OWO and depression among youth. However, no study has examined the association between income inequality and comorbid OWO and depression or tested potential mechanisms involved. We aimed to identify the association between income inequality and comorbid OWO and depression and to test whether social cohesion mediates this relationship.

Methods

We used data from the 2018–2019 Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking and Sedentary behavior (COMPASS) project. Our sample was composed of 46,171 adolescents from 136 schools distributed in 43 census divisions in 4 provinces in Canada (Ontario, Alberta, British Columbia, and Quebec). Gender-stratified multilevel path analyses models were used to examine whether income inequality (Gini coefficient) was associated with comorbid OWO and depression and whether the association was mediated by school connectedness, a proxy measure for social cohesion.

Results

The direct effect between income inequality and OWO-depression comorbidity was not significant. However, income inequality was significantly associated with increased risk of comorbidity via social cohesion. One standard deviation increase in the Gini coefficient was associated with a 9% and 8% increase in the odds of comorbidity in females (OR=1.09; 95% CI=1.03, 1.16) and males (OR=1.08; 95% CI=1.03, 1.13).

Conclusion

Policies aimed at reducing income inequality, and interventions to improve social cohesion, may contribute to reducing the risk of OWO-depression comorbidity among adolescents.