Whereas the smoking prevalence rates in the general population are declining, rates among people diagnosed with attention-deficit hyperactivity disorder (ADHD) continue to be elevated. Smoking may be a form of self-medication in people with ADHD, which has specific reinforcing mechanisms such as improvement of ADHD core symptoms, enhancement of moods and arousal, or a combination of both. In addition, the reinforcing effects of smoking may be potentiated by stimulant medication.