Sitting, screen time and suicide: the relationship between sedentary activity and suicide ideation in Canadian adolescents and young adults.

Introduction: Suicide is the second leading cause of death among 15- to 24-year-olds in Canada. At 21.4%, suicide rates among adolescents have remained constant despite declining rates in other developed countries. More than 50% of adolescents who commit suicide have a major depressive disorder. Objective: To investigate whether a link exists between sedentary activity and suicide ideation in Canadians aged 15 to 24 years. Methods: Using an initial sample of 8356 from the Canadian Community Health Survey (CCHS), Cycle 4 (2007/2008), 7914 adolescents and young adults aged 15 to 24 years were included in the analysis. We conducted Breslow-Day tests for effect modification to determine the need for stratification and multivariate logistic regression analysis to assess the relationship between sedentary activity and lifetime suicide ideation. Sedentary activity was classified into three categories: 0 to 15, 15 to 34 and 35 plus hours per week. Results: Those who were sedentary 15 to 34 h/wk had odds ratio (OR) of lifetime suicidal ideation 1.18 times higher (95% confidence interval [CI]: 0.99-1.41) than those who were sedentary 0 to 15 h/wk, while those who were sedentary 35+ h/wk had OR 1.41 times higher (95% CI: 1.15-1.74) than those in the least sedentary group. When controlling for sex, age, self-perceived health, self-perceived mental health and body mass index (BMI), as well as modelling an interaction between sex and self-perceived health and between sex and BMI, the relationship between suicide ideation and sedentary activity for youth and young adults in the 35+ h/wk exposure category remained significant with an adjusted OR of 1.33 (95% CI: 1.06-1.68), whereas that for those in the 15 to 34 h/wk exposure category was non-significant at 1.11 (95% CI: 0.92-1.35). To interpret the interaction terms, we explored sex-stratified models. For males reporting poor/fair self-perceived health, OR of lifetime suicidal ideation was 1.26 (95% CI: 0.82-1.26) whereas for females OR was 2.33 (95% CI: 1.68-3.23) compared with the reference (good/very good/excellent self-perceived health). A 10-unit increase in BMI decreased odds of lifetime suicide ideation for males by 0.97 (95% CI: 0.73-1.28), whereas it increased odds of lifetime suicide ideation by 1.58 times (95% CI: 1.29-1.92) for females. Conclusion: A relationship exists between sedentary activity levels and lifetime suicide ideation among youth and young adults with 35 or more hours of sedentary activity per week. This is of concern as a greater proportion of adolescents and young adults spends more time being sedentary. However, the cross-sectional nature of the CCHS does not permit us to comment on the direction of this relationship. Further research using longitudinal data is recommended. [ABSTRACT FROM AUTHOR]