Depression. What do we do next?

When my brother completing his post graduation,he got attacked by depression. I don't know about the cause. It may be bacause of break up or combination of family issue. He once attempted to suecide. Than we took him to a psychiatrist near us. So he give proper medication to my brother and it also worked. After 3-4 month of medication he came under a normal condition. After 1 year he stopped taking the medicine because the medicine were affecting in a negative way as told by him. So we thought he is fit now so medicines are not necessary for him. Then 2-3 months of stopping medicine the abnormal behavior started. Now he is taking medicine from a doctor but the improvement is very slow. What do we do next?Plz help us...