my brother is depressed, but the part i cannot understand is he chooses to wet himself and soil, why

My brother was abused, not sure how many times but once is enough to manifest into what he is at the moment. Thankfully, my brother has recently agreed he is unwell, and agrees he needs help. So at the moment he is undiagnosed of the type of depression. I find it so hard to believe that he let himself sit and urinate as and when. But chose not to when upstairs near the bathroom. He also used to urinate in the back room of where he lives with our mother. He has also soiled himself. Doesnt wash any of his clothes, he got to the last pair of trousers and just continuously take them off at night and put them back on in the morning. My brother was never like this, he used to own his own home and be house proud, but he has lost everything and has no reaction whatsoever. He drinks way too much. But when he finally had the doc, the doc told him to cut down to 4 cans a day and prescribed citalopram. He came to my home and had a bath something which i asked him why dont you want to wash, why are you sitting in urine, he said its for all his sins. My friend who is a survivor of child abuse, explained to him that what ever is controlling him is the manifestation of what was forced onto him and that it is his abusers sins he is sitting in not his sins for he has not comitted any and does not deserve to sit in it, a lot more went into the conversation, but the good thing is that for 4 days he did not wet himself. but , today i think he has, he will not wash or do anything for himself at all apart from go to the shop and buy his cans. Teeth are black and broken nails 3 inches long nothing good i can say about him its all self destruction, no self worth or awareness, just no reaction, can anyone comprehend this? Thanks for your time