Safety and Feasibility of DBS for Bipolar Depression

Inclusion Criteria: * Age 22-70 years * Ability to provide written informed consent * Primary diagnosis of Bipolar I Disorder confirmed by SCID-5 * Current major depressive episode (MDE) of at least 12 months duration * Stable control of mania for a minimum of 1 year * Agreement to remain on current anti-mania medication regimen * Hamilton Depression Rating Scale-17 (HDRS-17) score ≥20 at screening and baseline * Young Mania Rating Scale (YMRS) score \<12 at screening and baseline * Treatment-resistant depression: failure to respond to at least 4 adequate trials of antidepressant treatment in the current episode. Antidepressant treatments include: Medications (Must include 2 antidepressant medications from different pharmacological classes), Psychotherapy, ECT, repetitive transcranial magnetic stimulation (rTMS), IV ketamine or intra-nasal esketamine. * All patients must be receiving at least one mood stabilizing medication at entry into the trial. Medication regimen must be stable for a minimum of 4 weeks before the baseline visit. * Able to provide informed consent * English-speaking * Deemed suitable surgical candidate by neurosurgical evaluation * Under care of treating psychiatrist willing to collaborate with study team * Able to reside in New York Metropolitan area during first 6 months or willing/able to travel monthly to study site * Provision of at least two emergency contacts age ≥22 residing within reasonable proximity Exclusion Criteria * Current manic or hypomanic episode (YMRS ≥12) * Rapid cycling pattern (≥4 mood episodes in the past 12 months) * Active suicidal ideation with intent or plan * Suicide attempt within six months prior to baseline * Current psychotic symptoms * Primary diagnosis of schizophrenia, schizoaffective disorder, or other psychotic disorder * History (current and/or lifetime) of one or more schizophrenia-spectrum or other psychotic disorders including: schizophrenia, schizoaffective disorder, schizophreniform disorder, delusional disorder, and major depressive disorder with psychosis (unipolar or bipolar), and/or psychotic depression (unipolar or bipolar) (does not include psychosis occurring in the context of a manic episode of a subject with bipolar disorder) * Substance use disorder (moderate or severe) within 6 months * Presence of any type of dementia / Major Neurocognitive Disorder / significant cognitive impairment interfering with study participation * Subject has had a prior VNS Therapy or deep brain stimulation (DBS) implant * Subject has a diagnosis of Substance Use Disorder as defined by the DSM-V without sustained remission (12 months or longer) * History of borderline or severe personality disorder, as determined by clinical judgment, which would significantly interfere with a subject's participation in the study * Active primary diagnosis of one or more of the following disorders: obsessive-compulsive disorder, eating disorder, or post-traumatic stress disorder * Cognitive or psychiatric deficit (e.g., amnesia, delirium) that in the investigator's judgment would interfere with the subject's ability to accurately complete study assessments * Current or lifetime history of psychotic features in any major depressive episode (MDE) * Treatment with another investigational device or investigational drugs * Contraindications to MRI (metallic implants, claustrophobia unmanageable with anxiolytics) * Contraindications to general anesthesia or neurosurgery * Significant structural brain abnormalities precluding safe electrode placement * Active infection or immunocompromised state * Active unstable medial condition (diabetes, heart disease, hypertension, cancer, endocrine) * BMI \>35; and/or CRP \>3 * Coagulopathy or anticoagulation that cannot be safely interrupted * Pregnancy or planning pregnancy during study period * Women of childbearing potential unwilling to use effective contraception * Prisoners or institutionalized individuals * Decisionally impaired individuals (unless previously consented when capacitated) * Special status patients (employees, VIPs, celebrities, public figures) unless consented before special status known