Significant relationship between lifetime alcohol use disorders and suicide attempts in an Australian schizophrenia sample

Objective: Suicide and attempted suicide are common in individuals with schizophrenia, and evidence exists for a link between substance use disorders and suicidality in this disorder. However, alcohol has not been consistently implicated. We examined the relationship between substance use disorders and suicide attempts in schizophrenia. Methods: We recruited a schizophrenia sample in Australia (n = 821) for genetic analyses. We analysed demographic and clinical variables, including substance use disorders, and their relationship to suicide attempts using generalised equation modelling. Results: A significant association was identified between lifetime alcohol abuse/dependence and suicide attempts (OR = 1.66; 95% CI, 1.23 to 2.24; p= 0.001) after adjustment for potential confounders, but not between cannabis abuse/dependence and suicide attempts, nor between other illicit drug abuse/dependence and suicide attempts. Polysubstance abuse/dependence was also not implicated. Conclusions: These results suggest that the presence of alcohol abuse/dependence may be a risk factor for suicide attempts in individuals with schizophrenia, independent of comorbid substance abuse/dependence.