Subjective and physiological emotional response in euthymic bipolar patients: a pilot study.

The euthymic phase of bipolar disorders may be associated with residual emotional and/or subsyndromal symptoms. The aim of this study was to compare subjective and physiologic emotional response to negative, neutral and positive emotion eliciting pictures between euthymic bipolar patients (n=26) and healthy controls (n=30). We evaluated emotional response using an emotional induction method with emotional pictures from the International Affective Picture System. We measured subjective emotional response with the Self-Assessment Manikin and physiological emotional response by measuring pupil size. No difference was found between euthymic bipolar patients and controls regarding subjective emotional response. However, upon viewing positive pictures, pupil dilation was significantly lower in euthymic bipolar patients compared to controls. This finding suggests that euthymic bipolar phase may be associated with reduced physiologic emotional response to positive valence, which is consistent with a more general negative emotional bias or can be understood as a residual emotional subsyndromal symptom.