Abnormalities in late positive components of event-related potentials may reflect a genetic predisposition to schizophrenia.

Event-related potentials (ERPs) were recorded at the Cz region during syllable discrimination tasks in siblings of schizophrenic probands. ERPs in these siblings were compared to those of normal controls and schizophrenics. Siblings, similar to normal controls, displayed an increase in amplitudes of N100 according to the allocation of their attention between two different channels (ears), Siblings different from normal controls, however, failed to demonstrate an augmentation of late positive components upon detection of target stimuli in the attended channel. Mean amplitudes of late positive components elicited by target stimuli in the attended channel for siblings were nearly equal to those of unmedicated schizophrenics, with these values in siblings being significantly smaller as compared to those of normal controls. Based on these results, it was concluded that abnormalities of late positive components in siblings may reflect a genetic predisposition to schizophrenia.