This study is about finding out if a special treatment called **VNS Therapy** helps people with **treatment-resistant depression**. VNS stands for Vagus Nerve Stimulation, which is a treatment that uses a small device implanted in the body to send electrical pulses to the brain. It's like a pacemaker for the brain! The study will compare people who get the VNS treatment to those who don't, to see who feels better after a year. People who have had depression for a long time or tried many treatments without success can join. They will be watched for 12 months and might continue in a longer study for up to 5 years. The study follows special rules to make sure it's safe and useful.

• Participants will be part of the study for at least 12 months, with possible continuation for 5 years.
• Participants must have tried at least four unsuccessful depression treatments before.
• Participants cannot join if they have certain mental health conditions like schizophrenia.