A LONGITUDINAL-STUDY RELATING P3 AMPLITUDE TO SCHIZOPHRENIA SPECTRUM DISORDERS AND TO GLOBAL PERSONALITY FUNCTIONING

Auditory and visual event-related potentials (ERPs) were recorded from first-degree relatives (adolescent offspring) of index cases with sch izophrenic disorder, affective disorder, or no psychiatric disorder (n ormal controls) at a mean age of 15 years. Nearly a decade later, thes e subjects (at a mean age of 25 years) were evaluated for Research Dia gnostic Criteria Schizophrenic Disorder, Schizoaffective Disorder, Uns pecified Functional Psychosis, and for DSM-III-R Axis II schizophrenia -related traits and disorders including schizotypal, schizoid, and par anoid features. It was hypothesized, based on Duncan et al (1987a, Dun can 1988), that reduction of P3 amplitude in the auditory (but not the visual) modality would predict subsequent schizophrenic-related outco mes in subjects from the schizophrenic disorder parental group. This s pecific expectation was not statistically supported. An unanticipated and statistically robust result linking P3 decrements (in both auditor y and visual modalities) with poorer Global Personality Functioning wa s observed for offspring from both psychiatric parental groups and the offspring of the normal control group. These data are consistent with the results of a large number of clinical studies of the P3 component that have demonstrated reductions in P3 amplitude in individuals expr essing a wide range of behavioral dysfunctions. Their importance lies in the fact that these P3 amplitude decrements were detected long befo re the overt behavioral symptoms were identified, and were nonspecific with respect to parental psychiatric diagnostic group.