'False-positive' self-reported psychotic experiences in the general population: an investigation of outcome, predictive factors and clinical relevance.

AIMS.: Self-reported psychotic experiences (SRPE) by individuals from the general population are often unconfirmed by clinical interview and referred to as 'false-positive' (FP) SRPE. FP SRPE have been suggested to represent the mildest form of risk along the extended psychosis continuum. However, little is known about their (clinical) outcome and evolution over time. Aims of this study were to prospectively examine, in individuals with FP SRPE, (1) the prevalence of remission, persistence and transition to validated PE at 3-year follow-up; (2) potential baseline psychopathological and psychosocial predictors of persistence of FP SRPE and transition to validated PE; and (3) whether those with persistent FP SRPE and validated PE already differed on psychopathology and psychosocial factors at baseline. We tested the hypotheses that (i) individuals with FP SRPE would be more likely to have SRPE and validated PE at follow-up; and (ii) that FP SRPE would be predictive of lower functioning and more psychopathology and help-seeking behaviour at follow-up.

METHODS.: Baseline (n = 6646) and 3-year follow-up (n = 5303) data of the second the Netherlands Mental Health Survey and Incidence Study (NEMESIS-2), a general population research project on prevalence, incidence, course and consequences of psychiatric disorders was used. Self-report of PE was followed by clinical interview to determine clinical validity. The presence of mood, anxiety and substance use disorders, childhood adversity, help-seeking and functioning as well as PE characteristics (number, frequency, distress and impact) were used in the analyses which included only individuals with complete data for both assessments waves (n = 4683).

RESULTS.: At baseline, 454 participants had any FP SRPE; of these 372 participants had complete follow-up data available. Those with baseline FP SRPE were significantly more likely to report SRPE (OR = 3.58; 95% CI 2.38-5.40, p < 0.001) and validated PE (OR = 6.26; 95% CI 3.91-10.02, p < 0.001) at follow-up. Baseline FP SRPE also predicted the presence of mood and anxiety disorders, reduced functioning and help-seeking at follow-up. Several baseline psychopathological, psychosocial and PE characteristics were predictive for the persistence of SRPE. These factors also differentiated groups with FP SRPE or validated PE from those with remitted FP SRPE at follow-up.

CONCLUSIONS.: 'FP SRPE' are not truly 'false' as they index risk for the development of clinically relevant psychotic symptoms, development of mood and anxiety disorders and reduced functioning. Self-reported PE, even unconfirmed, warrant 'watchful waiting' and follow-up over time, especially when they are reported by individuals with reduced psychosocial functioning and general psychiatric problems.