Unintentional overdose and suicide among substance users: a review of overlap and risk factors.

Substance use is a risk factor for suicide, suicide attempts, and fatal and non-fatal overdose, but to date, little has been done to integrate the research on suicidal behavior and overdose among substance users. This study reviews the literature on suicide and overdose among substance users with the goal of illuminating the similarities and differences between these two events. A structured review resulted in 15 articles (describing 14 unique studies) published between 1990 and 2010 that examined both overdose and suicide in samples of substance users. There is some evidence that substance users who attempt suicide are more likely to report an overdose and vice versa. This relationship may be partially explained by the fact that overdose is a common method of suicide. The results of the literature review also indicate that substance users with a history of both events may represent a group with particularly poor psychological and social functioning and severe drug-related problems. Further research is needed to understand the overlap of, and differences between, suicide and accidental overdose among individuals who misuse substances, particularly individuals who primarily use substances other than heroin. An improved understanding of the interrelationships between suicide and unintentional overdose among individuals who use alcohol or drugs is necessary to guide the development of effective prevention and intervention approaches. Published by Elsevier Ireland Ltd.