Risk of suicide ideation in comorbid substance use disorder and major depression

BACKGROUND: Suicidal behaviour is commonly associated with major depression (MD) and substance use disorders (SUDs). However, there is a paucity of research on risk for suicide ideation among individuals with comorbid SUDs and MD in the general population. OBJECTIVES: This study investigated the associated risk of suicide ideation in comorbid SUDs—cannabis use disorder (CUD), alcohol use disorder (AUD), drug use disorder (DUD) with major depressive episode (MDE) in a nationally representative sample. METHODS: Multilevel logistic regression models were used to analyze the 2012 Canadian Community Health Survey- Mental Health (CCHS-MH) data. This is a cross-sectional survey of nationally representative samples of Canadians (n = 25,113) aged 15 years and older residing in the ten Canadian provinces between January and December 2012. Diagnoses of MDE, AUD, DUD, and CUD were based on a modified WHO-CIDI, derived from DSM-IV diagnostic criteria. RESULTS: Comorbidity was found to be the strongest predictor of suicide ideation. Compared to those with no diagnosis of either a SUD or MDE, individuals with a comorbid diagnosis of AUD with MDE, CUD with MDE, or DUD with MDE were 9, 11 and 16 times more likely to have 12-month suicide ideation respectively. A diagnosis of MDE was a significant predictor of 12-month suicide ideation with about a 7-fold increased risk compared with individuals not diagnosed with either MDE or a SUD. CONCLUSION: Suicide is a preventable public health issue. Our study found a significantly increased risk of suicide ideation among persons who have comorbid SUD with MD. Effective integration of mental health and addictions services could mitigate the risk of suicide and contribute to better outcomes.