I agree first the physical, something far easier to diagnose, should be addressed. Then you can go from there. Sometimes when a person won't sit and talk, it is best to write them a letter/email. This way they can read it in their time. Sometimes when a person isn't healthy they using unhealthy coping skills like being overly defensive, disconnected or aggressive when people try to help. I hope your brother and your whole family can find some peace in all of this.