Prevalence of psychotic-like experiences and their association with depression symptoms among patients entering adolescent psychiatric care

Background: Psychotic-like experiences (PLEs) are common in clinical adolescent samples and form a continuum based on their frequency and intensity. PLEs can have harmful effects on both behaviour and affect. Methods: Prevalence and subjective distress due to PLEs were assessed with the Prodromal Questionnaire-Brief (PQ-B) and depressive symptoms with the Beck Depression Inventory (BDI-21A) among adolescents (N = 399; 71.7% female, mean age 14.9 years, range 13-18) entering specialized adolescent psychiatric services. Various PQ-B Distress scale cut-off points were tested for their ability to detect high and low BDI scores using the superiority index, the effect size for mean difference, and spline regressions. Results: The mean number of endorsed PLEs assessed with the PQ-B was 3.27 (SD 3.64; males: M 1.75; SD 2.78; females: M 3.89; SD 3.78), while mean PQ-B Distress scores were 20.33 (SD 18.03; males: M 11.84; SD 13.90; females: M 23.74; SD 18.40). The most common PLE within both genders were experiences of paranoia and suspiciousness, with a prevalence of 59.9%. BDI scores and PQ-B distress scores were strongly associated (r = 0.534, p<.001). Superiority indices, effect sizes, and spline regressions indicated that a low PQ-B Distress cut-off of 2 or 3 was most informative both when using BDI as a continuous variable and when dichotomized as mild depression (>= 10) or major depressive disorder (>= 16). Conclusion: PLEs are common among adolescent entering psychiatric care. Even a relatively small amount of distress due to PLEs indicates clinical levels of depressive symptoms.