Case Report: Beneficial Effect of Quetiapine Monotherapy in Bipolar Depression with Comorbid Obsessive-Compulsive Disorder (OCD)

Bipolar disorder (BD) and obsessive-compulsive disorder (OCD) frequently co-occur, presenting complex clinical challenges that often compromise treatment outcomes. This case report highlights the beneficial effects of quetiapine monotherapy in a 30-year-old female patient diagnosed with bipolar depression and comorbid OCD. Traditional selective serotonin reuptake inhibitors (SSRIs), the first-line treatment for OCD, can induce manic episodes in bipolar patients, necessitating alternative approaches. Quetiapine, an atypical antipsychotic, was administered at an initial dose of 150 mg/day and titrated to 400 mg/day over a 4-week period, with continuous monitoring of depressive and obsessive-compulsive symptoms. Over the course of six weeks, the patient exhibited significant improvements in depressive symptoms, as measured by the Hamilton Depression Rating Scale (HAM-D), and in OCD symptoms, measured by the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The Clinical Global Impression-Severity (CGI-S) scale further reflected overall symptom alleviation. Statistical analysis using paired t-tests demonstrated significant reductions in HAM-D (p = 0.0263) and Y-BOCS (p = 0.0202) scores, indicating a robust therapeutic response. Visual representations of symptom progression, dose-response relationships, and CGI-S score reduction supported the findings. This case underscores the efficacy of quetiapine monotherapy in treating bipolar depression with comorbid OCD, offering a safer alternative to SSRIs by mitigating the risk of manic switches. The results highlight quetiapine’s potential as a frontline treatment for similar dual-diagnosis cases, warranting further investigation through larger longitudinal studies.