The Bipolar Diathesis in Patients with Treatment Resistant Depression

Woo, Young Sup; Chae, Jeong Ho; Seo, Ho Jun; Song, Hoo Rim; Jun, Tae Youn; Kim, Kwang Soo; Bahk, Won Myong

Abstract

OBJECTIVE
In this study, we determined the prevalence of bipolarity in patients with treatment resistant depression (TRD) by investigating demographic and clinical characteristics, diagnostic subtypes, and illness outcome. METHOD: A medical record review of patients admitted to a university hospital with the diagnosis of major depressive disorder (MDD) was conducted. DSM-IV diagnoses at index hospitalization and six months after discharge and detailed clinical information were obtained. We categorized subjects into a TRD group or a non-TRD group and re-evaluated the patients using the recently proposed criteria for bipolar spectrum disorder (BSD). Patients in the TRD group were compared with patients in the non-TRD group with regard to the prevalence rate of BSD at the index hospitalization and at the end of the follow up period.
RESULTS
There were 281 patients diagnosed as MDD. At discharge, the number of patients who fulfilled the criteria for BSD was higher (p<.001) in the TRD group (32/68, 47.1%) than in the non-TRD group (8/213, 3.8%). At the end of six-month follow-up period, the diagnoses of 38 patients changed ; 18 (26.5%) in the TRD group were subsequently classified as having bipolar disorder, and seven (3.3%) in the non-TRD group (p<0.001). There was no difference between these two groups in other clinical and demographic variables.
CONCLUSION
The findings suggest that a large number of patients with TRD have a bipolar diathesis.