Heroin, crack, cocaibe as far as I know.
I have no time for him, it's mum I am worried
About
Yes, that's understandable but your mother probably wants the best for him. If anything happens to him she's likely to suffer very badly.
Get him help even if it means getting him sectioned. It's the best thing for your mother and your brother and when he comes out the other side, he might even thank you.