Age of onset of substance use in patients with dual diagnosis and its association with clinical characteristics, risk behaviors, course, and outcome: A retrospective study.

Research Question: Do patients with dual diagnosis (DD) with an early initiation of substance use and subsequent early onset substance use disorder (EOS) differ from those with late onset substance use disorder (LOS) regarding characteristics, sex-related risk behaviors, course, and outcome?

Objectives: The aim is to study EOS and LOS groups of patients with DD attending a treatment center with regard to clinical characteristics, type of psychiatric disorders, risk behaviors, and short-term outcome.

Materials And Methods: Retrospective chart review of patients diagnosed with DD ( = 307) with regard to the above variables. Diagnoses of both substance use disorders (SUDs) and psychiatric disorders were made by qualified psychiatrists as per the International Classification of Diseases, 10 revision.

Results: Among 307 participants with DD, 100 were in EOS group (onset of SUD before 18 years of age as assessed clinically) and 207 in LOS group. Cannabis as the primary substance was more prevalent in the EOS (30%) than that of the LOS group (12%). Psychotic disorders were more prevalent in the EOS group (41%) followed by mood disorders (30%), while the reverse was true in the LOS group (27.5% and 56.5%, respectively). When compared to the LOS group, the EOS group had higher number of psychiatric admissions, reported higher prevalence of risky sexual behaviors (unprotected sexual intercourse, multiple sexual partners, and history of sexual intercourse with commercial sex workers), showed poorer treatment adherence, and worse outcome regarding both psychiatric disorder and SUD (all differences significant at < 0.05).

Conclusions: DD patients differ significantly based on the age of onset of substance use. These may have therapeutic and management implications.