Study Comparing Antipsychotic Dose Reduction vs. Maintenance Treatment in Patients With Schizophrenia Spectrum Disorder: a Personalized Medicine Approach

The objective of this study is to respond to frequent requests from patients who wish to reduce or even stop their antipsychotic treatment once they have achieved clinical stability. Psychiatrists are reluctant to respond to these requests because the method for safely reducing or stopping antipsychotic treatment remains poorly understood. The investigators want to verify the existence of an interaction between treatment strategy and psychotic phenotype (cycloid psychosis vs. non-CP), i.e., in terms of functional remission, the benefit of the dose reduction strategy compared to the maintenance strategy will be greater in the CP group than in the non-CP group. To this end, patients will be randomly assigned to four groups based on their phenotype and treatment strategy (CP-dose reduction; CP-dose maintenance; non-CP-dose reduction; and non-CP-dose maintenance). Several hospitals throughout France are participating in this study, in which a random draw (called randomization) will be conducted to determine whether the physician will propose reducing the antipsychotic dose or maintaining it at the same dose for the patient. Patients included in this study will be adults aged 18 to 60 who have been diagnosed with a schizophrenic spectrum disorder (SS): schizophrenia, schizophreniform disorder, schizoaffective disorder, or brief psychotic episode. The antipsychotics studied are: * second-generation antipsychotics: amisulpride, aripiprazole, olanzapine, quetiapine, risperidone; * first-generation antipsychotics: chlorpromazine, flupentixol, haloperidol, levomepromazine, loxapine, pipotiazine, zuclopenthixol. 288 patients will be included and followed for 24 months. The inclusion period is 48 months. Fourteen follow-up visits are planned, every month for four months and then every two months. During these visits, self-questionnaires or cognitive tests will have to be completed by the patient, the caregiver, and/or the treating psychiatrist. Three blood samples wi