Late electrophysiological potentials and emotion in schizophrenia: A meta-analytic review.

INTRODUCTION: There is mixed evidence about emotional processing abnormalities in schizophrenia and schizoaffective disorder, with self-reports and clinician ratings indicating significant differences between patients and controls, but studies of in-the-moment, self-reported emotional experience finding only small differences between these groups. The current meta-analysis synthesizes statistics from studies measuring the P3 and LPP, two event-related potential (ERP) components sensitive to attentional allocation, to examine whether patients exhibit ERP response abnormalities to neutral and valenced visual stimuli. METHODS: Standardized mean amplitudes and standard errors of P3 and/or LPP waveforms (300-2000 ms) in response to neutral and valenced images were calculated for 13 studies (total n = 339 individuals with schizophrenia, 331 healthy controls). RESULTS: In response to neutral images, there were very small, non-significant differences in ERP amplitudes between patient and control groups (k = 9; Hedges' g = -0.06, 95% CI: -055, 0.43, p = 0.81). In contrast, patients showed a small, significant reduction in ERP amplitudes compared to controls in response to negative images (k = 13; Hedges' g = -0.32, 95% CI: -0.59, -0.05, p = 0.02) and a small, but nonsignificant, reduction in amplitudes in response to positive images (k = 7; Hedges' g = -0.27, 95% CI: -0.71, 0.18, p = 0.24). CONCLUSIONS AND IMPLICATIONS: The current review indicates that compared to controls, patients have slightly diminished P3 and LPP amplitudes in response to positive and negative stimuli. This small reduction may reflect decreased attention allocation, possibly indicating an abnormality during a distinct stage of early processing related to evaluating the motivational salience of a stimulus.