Objective: To determine whether the presence of comorbid depression influences response to psychological treatment for methamphetamine use.
Design: Randomised controlled clinical trial.
Setting and participants: Our study was conducted between 2001 and 2005 at two sites in Australia: the Hunter Region of New South Wales and the city of Brisbane, Queensland. The 214 participants, who were all using methamphetamine at least once a week in the month prior to the study, were self-referred or referred from health services or drug and alcohol clinical services. Participants were divided into two groups based on whether or not they had depressive symptoms at baseline.
Interventions: The control group received only a self-help booklet; the two treatment groups received either two or four counselling sessions involving cognitive behaviour therapy and motivational interviewing techniques to manage methamphetamine use.
Main outcome measures: Changes in methamphetamine use and depression at 5 weeks and 6 months after baseline.
Results: Over 70% of participants met criteria for depression at baseline, and depression was associated with significantly greater severity of methamphetamine use and related issues. Benzodiazepine use was significantly higher among depressed than non-depressed participants. Reductions in methamphetamine use between baseline and 5 weeks were independently predicted by comorbid depression, in favour of increased change among those with baseline depression. Depressed participants who received three or four counselling sessions showed a significant reduction in depression at 5 weeks. However, reductions in methamphetamine use and depression compared with baseline were no longer evident at 6 months.
Conclusions: Over the short term, comorbid depression did not negatively affect response to treatment, with some evidence of a dose-response treatment effect for reduction in depression. This was not maintained at 6 months, indicating that methamphetamine-focused treatment may not enable people with comorbid depression to make sustained improvement at the level of their counterparts without depression.
Trial registration number: ACTRN12611000355976.