Hamilton HK, Roach BJ, Bachman PM, et al. - Via an 8-site case-control study of 552 individuals meeting psychosis risk syndrome (PRS) criteria, researchers ascertained whether P300 event-related potential amplitude, which is insufficient in schizophrenia, was decreased in the PRS and correlated with clinical outcomes. In at-risk individuals vs healthy controls, target P3b (elicited by infrequent target stimuli) and novelty P3a (elicited by infrequent nontarget novel stimuli) amplitudes were decreased. In psychosis converters vs nonconverters, target P3b and not novelty P3a was significantly decreased, and in at-risk individuals smaller target P3b amplitude was correlated with a shorter time to psychosis onset. Individuals with the PRS who remitted had baseline target P3b amplitudes that were comparable to those of healthy controls and higher than those of converters and at-risk individuals who persisted to be symptomatic. Hence, shortages in P300 amplitude seemed to lead to psychosis onset. Including both conversion to psychosis and clinical remission, target P3b amplitudes may be especially sensitive to clinical outcomes in the PRS. Auditory target P3b amplitude exhibited a guarantee as a putative prognostic biomarker of clinical outcome in the PRS.