If can be cure if he wants to get healed because it will keeps on coming back. He needs to see the doctor immediately so that he will be given the right medication. Is he with a family or relative in London? The support system for people who are under going medication is needed. They cannot get cure alone. The family should be strong for him. They should adjust to what is happening on him. He cannot live normally until he is having a depression. Once he get lonely, he will remember all the lonely things that happens to him and the depression will kick again. The healing process will only start when he wants to get heal. If he wants to get heal, he will follow the doctors advises, and drink the medication. I just wish there are people around him that will support him.