alt Hacker NewsDon't know about the research, but I've always assumed that drinking has some correlation with psychological pathology. I drink myself, and would self-diagnose myself as being happy. However, drinking, particularly heavy drinking seems correlated to problems.
Drinking is often (not always) an escape. So if a kid is drinking more than experimentally or e.g. occasional weekend gatherings with friends, it's a good sign they are having trouble coping with something. Same would go for smoking weed, etc. A normal well-adjusted person is not driven to get intoxicated frequently.