Ocrelizumab for Psychosis by Autoimmunity

Inclusion Criteria: * Individuals of either sex, 18-35 years of age. * Having an active psychotic disorder meeting DSM-5 criteria, including a duration of at least six months, for Schizophrenia Spectrum Disorder, as defined by the Mini International Neuropsychiatric Interview (MINI). * A total PANSS ≥ 60 and a score ≥ 4 on at least 2 of the PANSS positive symptoms. * Normal academic performance at least until the age of 15 years and absence of psychiatric symptoms before the same age. * Ability to assent or consent to the performance of the study and participate in testing procedures. Exclusion Criteria: * The dose of antipsychotic medication (if they are on one) has been changed less than two weeks prior to baseline PANSS testing (Visit 2, see below). * Patient treated with a medication designed to suppress the immune system, other than standard analgesics or antipyretics, in the six months prior to randomization. * Vaccinated with a live-attenuated vaccine less than 4 weeks before ocrelizumab infusion or with a non-live vaccine less than 2 weeks before infusion. * Active infection, or history of or known presence of recurrent or chronic infection (for example, hepatitis B or C, Human Immunodeficiency Virus, syphilis, tuberculosis, PML). * History of brain tumor, stroke, severe head trauma or multiple sclerosis. * Active cancer, metabolic encephalopathy, severe cardiovascular or renal disease. * In the judgment of the PI, psychosis related to substance abuse or metabolic disorders. * Pregnancy or lactation. * Requirement for chronic treatment with systemic corticosteroids or immunosuppressants during the course of the study. * History of or currently active primary or secondary immunodeficiency. * History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies. * Contraindications to or intolerance of oral or IV corticosteroids.