The best way to show that you care, is doing the best you can to lead your loved ones in the right direction. Appreciating your peer or even family member as they are will make the bond even better. This is, however, very dangerous if let to affect how healthy they live. The moment you point out some weak points, you can be sure to get some resistance. They may even feel betrayed, but the fact is that the moment they shall realize how important it was for you to point it out; they will come thanking you for it.
A huge number of alcohol and drug addicts are gradually on the rise.