This is the thing. I can tell you about lots of my friends. One of them in particular had a drinking problem. We didn't know he had a drinking problem. His roommate didn't know he had a drinking problem. It wasn't until Christmas that he exploded on somebody, and they had to physically tackle that guy and get him to Kingston for recovery.
Why was he like that? Because he was part of Bravo Company PPCLI when they were hit by a mortar, and he was wounded and sent home early. His biggest issue was that he couldn't go back.