Subtle behavioural responses during negative emotion reactivity and down-regulation in bipolar disorder: A facial expression and eye-tracking study

Abnormal processing of emotional information and regulation are core trait-related features of bipolar disorder (BD) but evidence from behavioural studies is conflicting. This study aimed to investigate trait-related abnormalities in emotional reactivity and regulation in BD using novel sensitive behavioural measures including facial expressions and eye movements. Fifteen patients with BD in full or partial remission and 16 healthy controls (HCs) were given a computerised task in which they were instructed to 'react to' unpleasant and neutral pictures or 'dampen' their emotional response to aversive pictures. Participants rated their emotional response after each picture block, and eye-movements and facial expressions were recorded. Patients generally gazed less at unpleasant and neutral pictures during emotion processing and regulation. During emotional reactivity, patients exhibited stronger facial expressions to neutral pictures, a lack of facial expressions to unpleasant pictures, and more surprised facial expressions to both neutral and unpleasant pictures compared to HCs. The results point to subtle abnormalities in visual gaze patterns and facial displays of emotion between patients with BD during emotion processing and regulation. Aberrant eye-movements and facial displays could provide a more sensitive measure of emotional reactivity in BD than traditional behavioural measures, which could aid future diagnostic accuracy.