I am 26 and have been taking concerta since I was 18, with the exception of the time that I stopped to try Vyvanse [it didn't work out so well for me]. I continue to take it because it works ok, [though it is starting to lose it's effectiveness afte so many years] But there are days that I don't take it with no withdrawal effects and I don't feel that I need to take it.

I haven't heard of many true cases of addiction with these meds. A few cases of abuse, yes, but not of addiction.