Hyperbaric Oxygen Therapy for Persistent Post Stroke Depression

Inclusion Criteria: 1. Age between 50 -85 2. Suffered an ischemic stroke 6 months to 7 years prior to their inclusion 3. Treated or being treated by antidepressants for at least 3 months 4. Diagnosis of PSD based on HDRS-17 score of 17 and above. 5. Stable psychological and pharmacological treatment for more than three months prior to inclusion. 6. Subject willing and able to read, understand and sign an informed consent. Exclusion Criteria: 1. Inability to attend scheduled clinic visits and/or comply with the study protocol 2. Diagnosis of a psychiatric disorder prior to the recent stroke including: major depression, schizophrenia or bipolar disease. 3. Diagnosis of aphasia or major cognitive decline 4. History of Deep brain stimulation (DBS) 5. History of traumatic brain injury, brain tumors, brain surgery, chronic subdural haemorrhages, Epilepsy 6. Active malignancy 7. Substance use at baseline. 8. History of other neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Lewy body dementia (LBD), Frontotemporal dementia (FTD), Multiple sclerosis (MS), Amyotrophic lateral sclerosis (ALS), Creutzfeld Jacob disease (CJD), Multisystem atrophy (MSA), Pseudobulbar palsy (PSP), Corticobasal degeneration (CBD), Wernicke Korsakoff syndrome 9. Serious suicidal ideation 10. Renal or liver insufficiency, electrolyte imbalances 11. Chronic heart failure with ejection fraction of 30 or less 12. HBOT for any reason prior to study enrolment 13. Chest pathology incompatible with pressure changes (including active asthma or COPD) 14. Ear or Sinus pathology incompatible with pressure changes (above 3 otolaryngologist visits a year) 15. An inability to perform an awake brain MRI 16. No evidence of vascular related lesions in the brain MRI 17. Active smoking 18. Participation in another study