Background: This study tested the hypothesis that the amount of psychoactive substance consumed (frequency and/or quantity), life problems resulting from this use, and a DSM-IV diagnosis of substance abuse/dependence are independent risk factors associated with increased suicidal ideation in a population of psychiatric inpatients with major depressive disorder.

Method: 891 hospitalized patients with a primary diagnosis of nonpsychotic major depressive disorder (MDD) received a standardized, psychiatrist-administered assessment battery. To examine the relationship between admission suicidality and demographic, psychiatric history, and admission variables, chi-square analyses were used for categorical data and one-way ANOVAs were used for continuous indices. Stepwise hierarchical multiple regression analyses were performed to determine the set of variables that was independently related to admission suicidality level.

Results: There was general agreement between our findings and previous literature in regard to the association between severity of Axis I diagnosis, depressed mood, hopelessness, male gender, unemployment, involuntary treatment, and alcohol/drug problems and higher suicidal ideation. In our sample of hospitalized patients with unipolar major depressive disorder, higher current drug and/or alcohol dependency and high current use of alcohol or other substances of abuse were independently associated with higher levels of suicidal ideation.

Conclusion: This association with higher suicidal ideation lends support to the importance of treating patients for both alcohol/drug problems and depression in an effort to decrease their risk for future suicide. We hope that our findings will improve the care that patients with dual diagnoses receive.