Event-related Potential Correlates of Affective Response Inhibition in Bipolar I Disorder: Comparison with Schizophrenia

Objectives: Individuals with bipolar I disorder (BD) have difficulty inhibiting context-inappropriate responses. However, the neural mechanisms contributing to these difficulties, especially in emotional contexts, are little understood. This study aimed to inform mechanisms of impaired impulsivity control in response to emotion in individuals with BD, and whether response inhibition indices are altered to a similar degree in schizophrenia spectrum disorders (SZ). We examined alterations to behavioral performance and event-related potentials (ERPs) during inhibition to affective stimuli in BD, relative to healthy control participants (HC) and participants with SZ. Methods: Sixty-six participants with BD, 32 participants with SZ, and 48 HC completed a Go/No-Go task with emotional face stimuli while electroencephalography was recorded. Behavioral signal detection metrics (perceptual sensitivity, response bias) and ERPs (N200, P300) were measured and compared across groups. Results: Relative to HC, participants with BD showed reduced (1) discrimination of Go vs. No-Go stimuli (i.e. emotional vs. neutral faces); and (2) P300 amplitudes elicited by emotional faces. These results similarly extended to participants with SZ, in that BD and SZ groups did not differ on behavioral performance nor ERP amplitudes. Exploratory correlational findings showed associations between ERP amplitudes and behavioral indices as well as mood symptoms. Conclusion: Findings suggest the difficulty participants with BD and SZ experienced on the current affective response inhibition task lied largely in discriminating between facial expressions. Difficulties with discriminating emotional from neutral expressions may contribute to difficulties with appropriate behavioral responding in social-affective contexts for individuals with BD and SZ.