Brexpiprazole Treatment for Bipolar I Depression

Patient Inclusion Criteria: * Age: 18-75 * Male or female * Bipolar Disorder type I or type II * Current treatment-resistant depressive episode (with MADRS \>/= 24 and item 2 (reported sadness) \>/= 3) for a minimum of 2 weeks but \</= 52 weeks at screening visit and baseline visit * Patients must have failed at least one other treatment for the current depressive episode * If female and of childbearing potential, is using an adequate method of contraception. Adequate methods of contraception include abstinence; oral contraceptive pill or surgically implanted device; intra-uterine device; condom plus spermicidal foam or jelly; or tubal ligation * Is treated with a mood stabilizer (lithium and/or valproate and/or lamotrigine and/or quetiapine \</= 100mg/day) * The following laboratory values are within normal limits at Screening: CBC with differential; ferritin; extended electrolytes (sodium, potassium, chloride, calcium, magnesium, phosphate); thyroid function test(s); kidney function tests; hemoglobin A1c; lipid profile; prolactin * Normal EKG at Screening * Patient is able to give his(her) consent Patient Exclusion Criteria: * Is at high risk of suicide as defined by a score of \>/= 3 to item 10 of MADRS and/or in the clinical opinion of the investigator * Hypo(mania) episode with YMRS \>/= 8 * Psychotic symptoms as defined by a score of \>/= 4 to item 8 (content) of YMRS and/or in the opinion of the investigator * Is treated with fluoxetine OR carbamazepine * Is treated with risperidone OR olanzapine OR quetiapine \> 100mg/day OR ziprazidone OR any other antipsychotic * Is pregnant or lactating or absence of contraceptive treatment * Drug abuse or dependence as per DSM-V (MINI) * Unstable medical condition * Other unstable and/or untreated psychiatric condition, organic brain disorder, unstable and/or untreated medical condition such as hypothyroidism, hyperthyroidism, diabetes, cardiac condition, hypertension * Deficit in vitamin B12 or folate * Rapid cycling (more than 4 mood episodes per year) * Active or history of difficulty to swallow * Seizures not currently controlled with medications * Orthostatic hypotension defined as a drop in systolic blood pressure of at least 20 mmHg or of diastolic BP of at least 10 mmHg within 3 minutes of standing * A history of clinically significant cardiovascular disorders and cardiac arrhythmias * A low white blood cell count * Known eye disease * Involuntary, irregular muscle movements, especially in the face * Known hypersensitivity to Brexpiprazole and any components of its formulation * Known lactose intolerance or have hereditary galactose intolerance or glucose-galactose malabsorption, because Brexpiprazole and placebo tablets contain lactose (a disaccharide of glucose and galactose) * Active inflammatory disease including lupus, colitis, Crohn's disease, psoriasis, irritable bowel syndrome (IBS) * Mild or major neurocognitive disorder * Previous history of sensitivity/low tolerance to medications metabolized by CYP 2D6 inhibitors, or CYP 3A4 inducers Control Inclusion Criteria: * Age: 18-75 * Male or female * No current or past history of any psychiatric disorder * Patients must have failed at least one other treatment for the current depressive episode * If female and of childbearing potential, is using an adequate method of contraception. Adequate methods of contraception include abstinence; oral contraceptive pill or surgically implanted device; intra-uterine device; condom plus spermicidal foam or jelly; or tubal ligation * The following laboratory values are within normal limits at Screening: CBC with differential; ferritin; extended electrolytes (sodium, potassium, chloride, calcium, magnesium, phosphate); thyroid function test(s); kidney function tests; hemoglobin A1c; lipid profile; prolactin * Normal EKG at Screening * Patient is able to give his(her) consent Control Exclusion Criteria: * Alcohol or drug abuse * Deficit in vitamin B12 or folate * Seizures not currently controlled with medications * History of clinically significant cardiovascular disorders and cardiac arrhythmias * Mild or major neurocognitive disorder Patient/Control Exclusion Criteria for MRI: * Pacemaker * Heart/vascular clip * Metal prosthesis * Metal fragments in body * Transdermal patch * Aneurysm clip * Prosthetic valve * Claustrophobia * Pregnant