I'm sure some people, as you say, have depression and anxiety where a new lifestyle and thought process would not be enough to maintain a healthy lifestyle. I think they should take medication, if required, and also should be working AA and/or counseling.
It's quite a thing to watch someone drink themselves to death, i was privvy to this when i was drinking first hand. It's quite a thing and i don't think anyone can understand this really if they are not an alcoholic.