The ATP Project (Antipsychotic-TEP-Psychosis)

Inclusion Criteria: * Admission to the PEP clinic in Estrie, either outpatient or inpatient, according to the transdiagnostic PEP model. * Willingness to begin taking an AP (regardless of type and dose, or change in type and dose during the study). * Ability to read and express themselves in French or English. * Capable of understanding and signing consent. Exclusion Criteria: * Pregnancy, childbirth in the last 6 months, or breastfeeding. * Presence of a metallic object in the body that is incompatible with MRI. * Any use of APs for more than 2 continuous weeks in the past year and/or 6 weeks in a lifetime (except for aripiprazole if taken at less than 2.5 mg/day or quetiapine at less than 50 mg/day, regardless of duration or timing of the prescription). * The following comorbidities: psychosis + borderline or intellectual disability, autism spectrum disorder, substance use disorder with decompensation, psychosis induced by a medical condition, or psychosis induced by drug use or withdrawal. * Type 1 diabetes. * Uncontrolled acute suicidal ideation. * Other conditions that could interfere with participation according to the judgment of the qualified physician.