Assessment of Psychotic Experiences in Youth

Six types of psychotic experiences were assessed: paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, all via self-report, and negative symptoms via parent report. The online supplementary appendix provides further details. Paranoia was assessed with 15 items from the Paranoia Checklist.^{21 (link)}Hallucinations were assessed with 9 items from the Cardiff Anomalous Perceptions Scale.^{26 (link)}Cognitive disorganization was assessed with 11 items from the short Oxford-Liverpool Inventory of Feelings and Experiences.^{27 (link)}Grandiosity was assessed with items from the “Myself” subscale of Cognition Checklist for Mania-Revised,^{28 (link)} the Peters and colleagues’ Delusions Inventory,^{29 (link)} and items developed from clinical case studies. Anhedonia was assessed with 10 items from the anticipatory pleasure subscale of the Temporal Experience of Pleasure Scale³⁰ (the scale was reversed so that higher scores indicated more anhedonia). Parent-rated negative symptoms were assessed with 10 items devised from the Scale for the Assessment of Negative Symptoms.³¹ For negative symptoms, both self-report and rater (parent) report were employed, in line with recent recommendations.^{32 (link)}Finally, distress was assessed with an item at the end of each of the paranoia, hallucinations, cognitive disorganization, and grandiosity subscales.