The Dual-System Hypothesis of Bipolar Spectrum Disorders: A Meta-Analysis

Abstract

Bipolar spectrum disorders are characterized by alternating intervals of extreme positive and negative affect. We performed a meta-analysis to test the hypothesis that such disorders would be related to dysregulated reinforcement sensitivity. First, we reviewed 22 studies that reported the correlation be-tween self-report measures of (hypo)mania and measures of reinforcement sensitivity. A large relation-ship was found between (hypo)mania and reward sensitivity (g = .75), but not with punishment sensi-tivity (g = -.05). This stands in contrast to self-reported depression which was found to have a small, negative relationship with reward sensitivity and a large positive one with punishment sensitivity (Katz et al., 2020). Next, we reviewed 32 studies that compared reinforcement sensitivity between euthymic, bipolar participants and healthy controls. There, bipolar disorder had a small, positive relationship with reward sensitivity (g = .19) and a medium, positive relationship with punishment sensitivity (g = .64). These findings support a dual-system theory of bipolar disorders, wherein reward sensitivity is more closely related to mania and punishment sensitivity more closely to bipolar depression. Bipolar disorders show diatheses for both states with euthymic participants being hypersensitive to both rewards and punishments. Implications for further theory and research practice are expounded upon in the discussion.