Marijuana impacts mood in bipolar disorder: a pilot study.

Patients with bipolar disorder (BP) often report subjective mood improvements after smoking marijuana (MJ); however, empirical studies supporting this claim have not been conducted. We conducted this study to determine if marijuana has an impact on mood in bipolar patients who smoke marijuana (MJBP), hypothesizing MJBP participants would experience improved mood after smoking MJ. All participants completed electronic mood ratings three times daily and recorded episodes of MJ use using Palm Pilot devices in their own environments in order to examine the impact of MJ use on mood in MJ-smoking bipolar patients (n = 12) and pure MJ smokers (MJ; n = 20). Difference scores were calculated between pre and post-MJ scales. Patients with BP (n = 11) who did not smoke MJ were also included as a comparison group. Significant mood improvement was observed in the MJBP group on a range of clinical scales after smoking MJ, while the MJ group reported a slight worsening of symptoms. Notably, total mood disturbance, a composite of the Profile of Mood States, was significantly reduced in the MJBP group, but increased in the MJ group after smoking. Further, while the MJBP group reported generally worse mood ratings than the BP group prior to smoking MJ, they demonstrated improvement on several scales post-MJ use as compared to BP participants. These data provide empirical support for anecdotal reports that MJ acts to alleviate mood-related symptoms in at least a subset of bipolar patients and underscore the importance of examining MJ use in this population.