In the small town I used to live in the meth heads were not young people, but 40 somethings usually. They neglected their kids, lost work, and aged before your eyes. Most of the meth arrests there involved parents between the ages of 38 and 48, a couple of friends and then one teenager - usually the son of one of the other older suspects. It was a pattern.
I remember being in a restaurant once talking to a young girl (20 or so) who I knew to be a meth user. She kept staring at a guy who was making a delivery across the street saying "I know that guy. I know that guy from somewhere but I can't place him." After about ten minutes of this, her face lit up and she said "I know. That's Bob. I used to sleep with him when I was in _____" I was floored, but that's the meth world.