Hello! Please remember that my response is for information only, we are not establishing a therapeutic relationship.
It sounds like you are very worried about your brother, and understandably so.
Because of HIPAA (federal law protecting private health information) and other laws pertaining to confidentiality, you cannot find out anything about your brother's treatment unless he signs what's called a "release of information," for you to do so.
Unfortunately, unless his situation becomes an emergency (like if he appears to be in imminent danger of harming himself), you cannot seek help for him. The best you can do is express your concern, point out what you see, and in a very loving and empathic way tell him that you would like to help. It sounds like this might be difficult --since he has not been forthcoming with information.
Please feel free to follow up with me.