My Brother Who Is On Peritoneal Dialysis Which He Does

My brother who is on peritoneal dialysis which he does not do as prescribed by his doctor has become almost totally incontinent bowel movements daily, often more than once. He is very stubborn despite my nagging him to go see someone. Any possible causes besides diet? He is 73 years old, in very poor health, morbidly obeses and likely suffers depression. He lives alone and has terrible eating habits.