A new 17-year study of 176 boys, ages 6 to 12, who were treated with the stimulant medication methylphenidate, marketed as Ritalin and other brand names, confirmed previous findings that the risk of substance abuse during late adolescence and into early adulthood was lower in those receiving stimulant medications for their ADHD, compared with those not receiving stimulants. For the first time, however, the new study shows that risk of substance abuse was lowest in the group of boys who began stimulant treatment for ADHD at an earlier age.