Amplitude reduction of the P300 event-related potential component, elicited in the process of decision making, reflects attention-mediated processing deficits and is among the most replicated biological findings in schizophrenia, making it a candidate biomarker of psychosis risk. A recent study found that P300 amplitude deficits across auditory and visual modalities emerge early in the schizophrenia illness course and precede onset of full psychosis. 43 individuals meeting PRS criteria, 19 schizophrenia patients, and 43 healthy control (HC) participants completed baseline electroencephalography recording during separate auditory and visual oddball tasks. 2 subcomponents of P300 were measured: P3b, elicited by infrequent target stimuli, and P3a, elicited by infrequent non-target novel stimuli. Researchers found:
- Auditory and visual target P3b and novel P3a amplitudes were reduced in psychosis risk syndrome (PRS) and schizophrenia participants relative to HC participants.
- In addition, baseline auditory and visual target P3b, but not novel P3a, amplitudes were reduced in 15 PRS participants who later converted to psychosis, relative to 18 PRS non-converters who were followed for at least 22 months.
- Furthermore, target P3b amplitudes predicted time to psychosis onset among PRS participants.
Hamilton HK, Woods SW, Roach BJ, et al. Auditory and visual oddball stimulus processing deficits in schizophrenia and the psychosis risk syndrome: Forecasting psychosis risk with P300. [Published online ahead of print December 8, 2018]. Schizophr Bull. doi:10.1093/schbul/sby167.