Background: Identifying trait markers specific to schizophrenia might uncover mechanisms underlying illness susceptibility. Previous research shows the N2 and P3 event-related potentials are abnormal in schizophrenia; specificity of these potential trait markers has not been well established.
Methods: Electroencephalogram data were recorded from four adolescent groups: early-onset schizophrenia patients (SZ; n = 30); non-psychotic siblings of schizophrenia patients (SZ-SIB; n = 36); healthy control subjects (HC; n = 36); a neurodevelopmental attention-deficit/hyperactivity disorder (ADHD) comparison group (n = 27), during auditory oddball and visual go/no-go tasks. The P3 was measured to targets in the oddball task. The N2 and P3 were measured to go and no-go stimuli in the go/no-go task.
Results: Compared with the HC group, the SZ and SZ-SIB groups showed significantly reduced auditory oddball P3 amplitude. Visual P3 amplitude was significantly reduced in the SZ group for no-go stimuli and the SZ-SIB group for go and no-go stimuli. The P3 amplitude in the ADHD group was not significantly reduced for either paradigm. The SZ and ADHD groups showed significantly reduced N2 amplitude in the go/no-go task; the SZ-SIB group was not significantly different from the HC group.
Conclusions: Results revealed reduced P3 amplitude in schizophrenia patients and adolescent non-psychotic siblings in an auditory oddball and a visual go/no-go task. The SZ-SIB and ADHD groups showed a different ERP profile when each was compared with the HC group: siblings showed reduced P3 amplitude in both tasks and normal N2 in the go/no-go task; the opposite pattern was observed in the ADHD group.