Does occasional cannabis use impact anxiety and depression treatment outcomes?: Results from a randomized effectiveness trial.

This study investigated the extent to which occasional cannabis use moderated anxiety and depression outcomes in the Collaborative Care for Anxiety and Panic (CCAP) study, a combined cognitive-behavioral therapy (CBT) and pharmacotherapy randomized effectiveness trial. Participants were 232 adults from six university-based primary care outpatient clinics in three West Coast cities randomized to receive either the CCAP intervention or the usual care condition. Results showed significant (P<.01) evidence of an interaction between treatment group (CCAP vs. usual care) and cannabis use status (monthly vs. less than monthly) for depressive symptoms, but not for panic disorder or social phobia symptoms (all P>.05). Monthly cannabis users' depressive symptoms improved in the CCAP intervention just as much as those who used cannabis less than monthly, whereas monthly users receiving usual care had significantly more depressive symptoms than those using less than monthly. A combined CBT and medication treatment intervention may be a promising approach for the treatment of depression among occasional cannabis users.