Longitudinal invariance of psychotic experiences in children and adolescents: What do the data tell us?

Background: Psychotic experiences are common in adults, adolescents, and children. While usually self-limited, they can indicate psychosis proneness when persistent. The Community Assessment of Psychic Experiences (CAPE) measures lifetime psychotic experiences in three dimensions. The 20-item subscale addressing positive symptoms (CAPE-positive) is the most widely used. No study investigated its measurement invariance across timepoints during childhood and adolescence. This step is required to conduct reliable comparisons in longi-tudinal studies with different age groups. Methods: We used data from the Brazilian High-Risk Cohort, which enrolled 2511 individuals aged 6-12 years from public schools for the baseline evaluation. A 3-year follow-up assessment evaluated 1880 participants. Subjects were rated with the CAPE-positive and we performed, at each wave, a Multigroup Confirmatory Factor Analysis testing Exploratory and Confirmatory Factor Analysis models identified in a previous systematic review, to assess longitudinal invariance. Results: A three-factor solution was the best fitting model, comprising Persecutory Ideation, Bizarre Experiences and Perceptual Abnormalities. The longitudinal invariance analysis of the best-fit model was unsatisfactory, achieving only the metric level of invariance. Conclusions: Our findings suggest that the CAPE-positive scale has good model fit indices for each evaluated time point individually (children and adolescents), but it is not invariant over time. Identifying which factors affect CAPE latent structure at different time points can improve our understanding of psychosis proneness and how to measure it.