확률적 보상과제를 이용한 기분안정기 양극성 장애 환자의 보상학습 특성

Reward Learning in Euthymic Patients with Bipolar Disorder Using a Probabilistic Reward Task

본 연구는 확률적 보상과제를 이용하여 양극성 장애 안정기에 있는 환자에서 보상학습특성을 살펴보았다. 그 결과 양극성 장애 환자는 안정기 상태에서 정상인에 비해 반응편향의 감소가 관찰되었다. 그 외 두 군 간에 변별력, 정답률 및 반응시간에는 차이가 없어 과제 수행능력에는 차이가 없는 것으로 나타났다. 본 결과는 양극성 장애 기분안정기 환자들의 보상학습에 문제가 있음을 시사하는 것으로 보인다.

Objective Bipolar disorder patients often show excessive goal-directed and pleasure-seeking behavior during manic episodes and reduced hedonic capacity during depressive episodes, indicating that bipolar disorder might involve altered reward processing. As such, bipolar disorder subjects have been reported to show impaired reward learning in situations requiring integration of reinforcements over time. In this study, we examined characteristics of reward learning in euthymic patients with bipolar disorder using a probabilistic reward task. Methods We recruited 23 euthymic patients with bipolar disorder and 47 healthy subjects for the probabilistic reward task. This task is a reward-based paradigm to produce a response bias, in which correct identifications of two ambiguous stimuli are differently rewarded. The other dependent measures were the discriminability, hit rate and reaction time. Results Relative to comparison subjects, bipolar patients showed a reduced acquisition of response bias toward the more frequently rewarded stimulus (p＜0.01). The overall reward learning was positively correlated with state and trait anxiety levels in bipolar patients (p＜0.01). No significant differences of discriminability, hit rates, and reaction time were found between bipolar patients and controls. Conclusion These findings suggest that euthymic patients with bipolar disorder may have deficits in reward learning related to anxiety.