Treatment Resistant Depression and Vagus Nerve Stimulation

Inclusion Criteria: * Patients aged 18 years and older ; * Childbearing women must have an efficient contraception for the whole study period * Diagnosis of recurrent depressive trouble or persistent depressive disorder or bipolar disorder (according to DSM-5) * Start of disorder (defined by the occurrence of the first thymus episode: characterized depressive disorder or maniac episode with or without mixed characteristics) for 5 years or more * At least one of the following criteria: * Criterion A: current characterized depressive disorder and characterized depressive disorder for at least 12 months during the last 24 months despite at least four treatments lines at appropriate dosage and duration * Criterion B: current treatment by ECT/(Es)Ketamine/TMS and criteria A before the start treatment or ECT/(Es)Ketamine/TMS dependency * Patients who, after the nature of the study has been explained to them, have given written consent Exclusion Criteria: * Know pregnancy or breastfeeding * Schizophrenia, schizoaffective disorder or persistent delusional disorder (DSM-5) * Characterized depressive disorder with psychotic characteristics within 3 months before the inclusion (DSM-5) * Concomitant participation to another interventional research not authorized by the coordinating investigator or the scientific lead. Participation to non-interventional researches is allowed. * Patients receiving enforced cares (ASPDT, ASPPI, ASPDRE, etc.) * Non-affiliation to a social security regimen or any other social protection regimen * Disability, according to the investigator, to understand the study or refusal to sign the study consent form (non-francophone patient, cognitive disorders) * Anticipated disability to attend all the visits, treatments and measures planned by the protocol: severe personality disorder, severe substance addiction, severe intellectual development disorder. In any of those cases, the notion of severity is at the indiscretion of the investigator Secondary Exclusion Criteria: * Surgical contraindication to the VNS * Positive β-HCG (results obtained after the informed consent is signed but before the randomization)