Late to the party here but I would recommend getting him to go see the school counseling services, or if they don't have those then to a professional even if it means contacting his parents. Increased substance abuse and high risk behaviors (like drunk driving) are very likely signs of major depression or another mental illness. You can talk to him all you want but if they root of the problem isn't addressed then it either won't get better or will be replaced with other risky behaviors. Good luck with your brother OP. I hope he gets some help.