Electrophysiological correlates of selective attention in children and adolescents at high risk for schizophrenia.

As part of a research project on electrophysiological correlates of attention in young subjects at high genetic risk for schizophrenia, auditory event-related potentials (ERPs) associated with selective attention and automatic information processing were recorded in 21 adolescent (offspring of at least one parent with schizophrenia) and 21 control subjects marched for age, sex and socioeconomic status. The experimental task was a dichotic listening task, and accuracy of counting target pips served as a psychometric control variable. The results showed group-related differences in the ERPs, with a significant reduction being present in the high-risk group concerning the amplitude of the fronto-precentrally located negative difference (Nd) wave and the F3 component elicited by selectively attended stimuli. Comparison of individual matched pairs showed that reduced Nds, characterized 14/21 high-risk individuals and reduced P3s 16/21. Moreover, there were significant correlations between ERP reductions and psychometric deficit (counting accuracy). Finally, 13 latencies tended to be prolonged in the high-risk group. Mismatch negativity (MMN), an ERP correlate of automatic information processing, did not differ significantly in the two groups, although there was a marked reduction in amplitude in the high-risk group. The ERP alterations point to impaired selective attention in a considerable proportion of subjects at high genetic risk for schizophrenia.