Background: The treatment of bipolar disorder is often complicated by the presence of a co-occuring anxiety disorder. Although second generation antipsychotics are being used with increasing frequency in bipolar patients, their anxiolytic effects have not been well studied in this population.
Methods: The anxiolytic effect of risperidone 0.5-4 mg/day was tested in an 8-week, double-blind, placebo-controlled, randomized clinical trial in 111 patients with bipolar disorder and a co-occuring panic disorder or generalized anxiety disorder (GAD). The primary outcome measure was the Clinician Global Improvement-21 Anxiety scale (CGI-21 Anxiety). Secondary measures included the Hamilton Anxiety Scale (HAM-A) and the Sheehan Panic Disorder Scale.
Results: On the last-observation-carried forward analysis of repeated measures analysis of variance (ANOVA), risperidone was not more effective than placebo for the CGI-21 Anxiety score or the other anxiety outcome measures. Risperidone was well tolerated, with only two patients withdrawing because of adverse events.
Limitations: The risperidone treated group had more patients with mixed states and lifetime panic disorder at randomization than the placebo group. The study was limited to 8 weeks and to individuals with bipolar and comorbid panic disorder or GAD. The results may not be applicable to risperidone as an add-on treatment to mood stabilizers, or to bipolar disorder comorbid with anxiety disorders other than panic disorder or GAD.
Conclusions: Risperidone monotherapy was not an effective anxiolytic for bipolar patients with comorbid panic disorder or GAD in doses of 0.5-4 mg/day over 8 weeks of treatment. The efficacy of other second generation antipsychotics and mood stabilizers on anxiety in patients with bipolar disorder and a co-occuring anxiety disorder should be investigated in double-blind, placebo-controlled studies.