Phenotypically Continuous With Clinical Psychosis, Discontinuous in Need for Care: Evidence for an Extended Psychosis Phenotype

Rates of self-reported psychotic experiences (SRPEs) in general population samples are high; however the reliability against interview-based assessments and the clinical significance of false-positive (FP) ratings remain unclear. Design: The second Netherlands Mental Health Survey and Incidence Study-2, a general population study. Trained lay interviewers administered a structured interview assessing psychopathology and psychosocial characteristics in 6646 participants. Participants with at least one SRPE (N = 1084) were reassessed by clinical telephone interview. Thirty-six percent of participants with SRPEs were confirmed by clinical interview as true positive (TP). SPREs not confirmed by clinical interview (FP group) generated less help-seeking behavior and occurred less frequently compared with TP experiences (TP group). However, compared with controls without psychotic experiences, the FP group more often displayed mood disorder (relative risk [RR] 1.7, 1.4-2.2), substance use disorder (RR 2.0, 1.6-2.6), cannabis use (RR 1.5, 1.2-1.9), higher levels of neuroticism (RR 1.8, 1.5-2.2), affective dysregulation, and social dysfunction. The FP group also experienced more sexual (RR 2.0, 1.5-2.8) and psychological childhood trauma (RR 2.1, 1.7-2.6) as well as peer victimization (RR 1.5, 1.2-2.0) and recent life events (RR 2.0, 1.6-2.4) than controls without psychotic experiences. Differences between the FP group and the TP group across these domains were much smaller and less conclusive. SRPEs not confirmed by clinical interview may epresent the softest expression of an extended psychosis phenotype that is phenotypically continuous with clinical psychosis but discontinuous in need for care.