Phenotypically continuous with clinical psychosis, discontinuous in need for care: evidence for an extended psychosis phenotype.

Background: 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.

Methods: 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.

Results: 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.

Discussion: SRPEs not confirmed by clinical interview may represent the softest expression of an extended psychosis phenotype that is phenotypically continuous with clinical psychosis but discontinuous in need for care.