Mental and substance use disorders are often associated with an elevated risk for suicidal behaviors. The role of the co-occurrence of multiple disorders in this association is still unclear.

The Nigerian Survey of Mental Health and Wellbeing is a community survey of mental and substance use disorders as well as of suicidal outcomes. Face-to-face assessment was conducted using the World Health Organization’s Composite International Diagnostic Interview, version 3. A total of 6,752 adults, aged 18 years and over, were interviewed.

Persons with lifetime suicide attempt were more likely than those without attempt to have experienced lifetime DSM-IV disorders. Lifetime attempters were also more likely to have comorbid conditions. Compared with only 0.4% of persons with no history of lifetime attempts, over 11% of persons with lifetime attempt had three or more co-occurring disorders. Multivariate analysis controlling for the effects of comorbid conditions suggests that while mood disorder is independently associated with suicidal outcomes, comorbidity partly explains the association of anxiety disorders and almost fully accounts for the association of substance use disorders with suicidal outcomes.

Comorbidity is an important factor in the association of mental and substance use disorders with suicidal behavior.