Differences in Clinical Manifestations between Bipolar I and Bipolar II Disorders in Korean Population

Baek, Ji Hyun; Park, Dong Yeon; Park, Hae Jung; Choi, Jung Mi; Choi, Ji Sun; Noh, Ji Hye; Lee, Dongsoo; Hong, Kyung Sue

Abstract

OBJECTIVES
: Whether bipolar II disorder (BP-II) is simply a milder form of bipolar I disorder (BP-I) or a valid diagnostic category that could be separated from BP-I, is an issue still under consideration. Investigations exploring differential clinical and biological features of the two conditions are needed to resolve the controversies. This study aimed to obtain a comprehensive view of differences in clinical course and symptoms characteristics between BP-I and BP-II.
METHODS
: 44 BP-I and 26 BP-II patients were assessed using the Diagnostic Interview for Genetic Studies (DIGS), Korean version. Demographic data, age at onset, number of (hypo) manic/ depressive episodes, the duration of illness, polarity at onset, seasonality, rapid cycling, atypical depression and symptom profiles of each episode were evaluated.
RESULTS
: BP-II patients experienced depressive episodes more frequently than BP-I patients after illness onset (U=240.5, p=0.008). More BP-II patients showed seasonality (34.9% vs. 61.5%) and a rapid cycling course (4.5% vs. 18.2%). When comparing symptom profiles of manic/hypomanic episodes, irritable mood, decreased sleep need, inattention, reckless behavior, arrogant/provocative attitude and frequent outbursts of anger were less encountered in BP-II patients. In depressive episodes, leaden paralysis and psychomotor agitation were more frequently observed in BP-II patients. There was no significant difference between the two groups in psychotic symptoms of depressive episode.
CONCLUSION
: BP-I and BP-II disorders showed differences in clinical courses and symptom profiles. BP-II disorder seems to be less severe than BP-I disorder with regard to the intensity of manic symptoms, but more severe with respect to frequencies of depressive episodes. These results provide additional evidence supporting the distinction of BP-I and BP-II as separate diagnos-tic categories that might have different genetic profiles and/or biological mechanisms.