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

Abstract

OF THE THESIS vii APPENDIX A: PRISMA Checklist and Risk of Bias Assessment 33 APPENDIX B: Funnel Plots for All Included Studies 37 APPENDIX C: Moderator Information and Analyses 38vi ACKNOWLEDGMENTS I would like to express the deepest appreciation to my committee chair, Professor Elizabeth A. Martin, who has supported and guided me through the completion of this project. Without her steadfast and continued encouragement, this thesis would not have been possible. Introduction:There is mixed evidence about emotional processing abnormalities in schizophrenia and schizoaffective disorder, with trait 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 metaanalysis 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, viii 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. ABSTRACT Structured summary2 Provide a structured summary including, as applicable: background; objectives; data sources; study eligibility criteria, participants, and interventions; study appraisal and synthesis methods; results; limitations; conclusions and implications of key findings; systematic review registration number.2

Intact differentiation of responses to socially-relevant emotional stimuli across psychotic disorders: An event-related potential (ERP) study

“…The LPP is a centroparietal positivity that begins approximately 400 ms after the onset of an emotionally salient image that, in healthy individuals, is augmented when viewing unpleasant and pleasant images as compared to neutral images (Foti and Hajcak, 2008;Hajcak and Olvet, 2008). Schizophrenia patients have shown the typical pattern of elevated LPP to standardized emotional vs. non-emotional images in several studies (Horan et al, 2012;Horan et al, 2010;Okruszek et al, 2016;Strauss et al, 2015;Sullivan and Strauss, 2017), and these findings are consistent with broad meta-analytic work on P3/LPP in schizophrenia or schizoaffective disorder (Castro et al, 2019). While existing ERP studies point toward intact bottom-up neural responses to emotional stimuli in schizophrenia, the current study sought to extend this line of investigation by addressing three open questions.…”

Electrophysiological responses to images ranging in motivational salience: Attentional abnormalities associated with schizophrenia-spectrum disorder risk

“…These findings are consistent with results from a recent meta-analysis of P3/LPP amplitude differences in individuals with schizophrenia vs. controls. Specifically, Castro and colleagues 51 found that across 13 studies (including 339 individuals with schizophrenia and 331 healthy controls), there was a very small, non-significant difference between the groups in response to neutral images (Hedges' g = −0.06, 95% CI = −0.55, 0.43). This suggest that using neutral images as a "baseline" from which to compare groups' responses to affective images can be an empirically-informed decision.…”

Altered P3a Modulations to Emotional Faces in Male Patients With Chronic Schizophrenia

“…[5][6][7] Several meta-analyses of functional magnetic resonance imaging and EEG studies have consistently revealed impairments in facial emotion processing in patients with schizophrenia. [8][9][10][11] Event-related potentials (ERPs) such as the visually evoked N170 component, a negative response recorded at occipitotemporal electrodes at around 170 ms, can be used to assess face processing. The N170 is thought to reflect the early phase of face processing.…”

“…5-7 Several meta-analyses of functional magnetic resonance imaging and EEG studies have consistently revealed impairments in facial emotion processing in patients with schizophrenia. 8-11…”

“…Thus, findings on the P3 have been mixed, and the P3a has been examined less frequently than the N170 in the schizophrenia literature. Castro et al 11 performed a comprehensive search and found 13 studies for P3a and/or late positive potentials to emotional faces or objects in schizophrenia. In their meta-analysis, patients showed significantly smaller ERP amplitudes in response to negative images than healthy subjects, and no significant amplitude differences in response to positive images.…”