Auditory ERP components before and after transition to a first psychotic episode

► N1 amplitudes show significant reductions from before until after psychotic onset. ► P3 amplitudes are reduced before, but do not show changes after psychotic onset. ► In UHR subjects, a differential breakdown occurs in processes that regulate the inflow of information from the environment before and after psychotic onset. We investigated the course of Event Related Potentials (ERP) from prior to until shortly after a first psychotic episode in subjects at Ultra High Risk (UHR) for psychosis. N1, N2, N2b, P2 and P3 amplitudes were assessed using an auditory active oddball paradigm in 15 UHR subjects who made a transition to psychosis (UHR + T) at follow up, 23 subjects without a transition (UHR + NT) and 17 matched healthy controls at inclusion and again after approximately 18 months. Repeated-measures analyses revealed no significant time effects for any of the ERP components. However, an interaction effect was found for N1 amplitudes. Post-hoc analyses showed that N1 amplitudes were smaller at follow up compared to baseline only in UHR + T subjects. P3 amplitudes showed no further reduction after psychotic onset. These findings suggest that discernable ERP components behave differently during progression from the prodromal phase to the first psychotic episode. These findings may give insight in pathophysiological mechanisms underlying the genesis of psychosis.