First controlled treatment trial of bipolar II hypomania with mixed symptoms: quetiapine versus placebo.

Objectives: To compare the efficacy and safety of adjunctive quetiapine (QTP) versus placebo (PBO) for patients with bipolar II disorder (BDII) currently experiencing mixed hypomanic symptoms in a 2-site, randomized, placebo-controlled, double-blind, 8-week investigation.

Methods: Participants included 55 adults (age 18-65 years) who met criteria for BDII on the Structured Clinical Interview for DSM-IV-TR (SCID). Entrance criteria included a stable medication regimen for ≥2 weeks and hypomania with mixed symptoms (>12 on the Young Mania Rating Scale [YMRS] and >15 on the Montgomery Asberg Depression Rating Scale [MADRS] at two consecutive visits 1-3 days apart). Participants were randomly assigned to receive adjunctive quetiapine (n=30) or placebo (n=25).

Results: Adjunctive quetiapine demonstrated significantly greater improvement than placebo in Clinical Global Impression for Bipolar Disorder Overall Severity scores (F(1)=10.12, p=.002) and MADRS scores (F(1)=6.93, p=.0138), but no significant differences were observed for YMRS scores (F(1)=3.68, p=.069). Side effects of quetiapine were consistent with those observed in previous clinical trials, with sedation/somnolence being the most common, occurring in 53.3% with QTP and 20.0% with PBO.

Conclusions: While QTP was significantly more effective than PBO for overall and depressive symptoms of BDII, there was no significant difference between groups in reducing symptoms of hypomania. Hypomania improved across both groups throughout the study.