Cerebellum-based Imaging Neural Markers for Antipsychotic Response

Inclusion Criteria: * Diagnosis of a first-episode psychotic disorder including: schizophrenia, schizophreniform disorder, schizoaffective disorder, brief psychotic disorder, psychotic disorder Not Otherwise Specified (NOS), bipolar disorder with psychosis, and major depressive disorder with psychosis; * Current positive symptoms rated \> 3 (moderate) on one or more of the Brief Psychiatric Rating Scale (BPRS) psychosis items: conceptual disorganization, grandiosity, hallucinatory behavior, and unusual thought content; * At early phase of illness as defined by having taken antipsychotic drugs for a cumulative lifetime period of 8 weeks or less; * Age 15 to 40; * Competent to sign informed consent. Exclusion Criteria: * Serious neurological or endocrine disorder or brain trauma; * Any medical condition which requires treatment with a medication with psychotropic effects; * Significant risk of suicidal or homicidal behavior; * Cognitive or language limitations, or any other factor that would preclude subjects providing informed consent; * Contraindications to antipsychotic monotherapy; * Contraindications to MR imaging (e.g. pacemaker); * Pregnancy by self report.