To examine the continuity of substance use disorder (SUD) in adolescent women during the transition to adulthood and to assess psychosocial functioning associated with SUD. Furthermore, to examine concurrent and longitudinal relationships between major depressive disorder (MDD) and SUD during this developmental transition.

One hundred fifty-five women, aged 17 to 19 years, were recruited from 3 high schools and were followed annually for 5 years. Comprehensive diagnostic and psychosocial assessments were performed with standardized instruments. The primary outcome measures included MDD and SUD during follow-up in those with and without a prior history of MDD or SUD, and psychosocial functioning associated with SUD.

The 5-year incidence of SUD was 9.6% and, by the end of follow-up, 18.7% had a lifetime episode. Prior SUD significantly increased the risk for SUD diagnosis during the study. Co-occurrence of MDD and SUD was high during adolescent and early adult years, with episodes of both disorders occurring in close temporal proximity. SUD also predicted MDD over time, but the reverse was not true. After controlling for the effects of MDD on social adjustment, SUD was associated with significant impairment in school functioning.

These results suggest that the risk for new onset and recurrence of SUD is high during the developmental transition to adulthood. SUD during this developmental period is associated with significant school-related problems. The findings also suggest that SUD and MDD frequently co-occur during the post-high school transition in women. Given the significant psychosocial dysfunction associated with these illnesses, early detection of these problems and effective intervention are crucial.