Elkins IJ, et al. - The effects of childhood attention deficit hyperactivity disorder (ADHD) symptoms, both inattention, and hyperactivity-impulsivity, were examined on the development of smoking in male and female adolescents. ADHD subtype and gender affected smoking initiation and escalation differentially. In female adolescents, the association of inattention with smoking could be causal, while hyperactivity-impulsivity appeared to act indirectly, through shared propensities for both ADHD and smoking.