The main objective of the TEA trial is to compare the efficacy and adverse reactions of two antipsychotics (quetiapine versus aripiprazole) in children and adolescents between 12-17 years of age with psychotic symptoms on psychopathology, cognitive deficits, and daily functioning. Furthermore, the trial will focus on adverse reaction profiles of the two antipsychotics as well as early predictors of later sustained clinical effects of these antipsychotics.