Shire Pharmaceuticals modified the guanfacine molecule to create a long acting preparation (Intuniv) that the FDA recently judged safe and effective for Attention Deficit Hyperactivity Disorder (ADHD) in children ages 6-17. Secondary analysis of data from the pivotal studies that led to this indication revealed that in ADHD children, Intuniv also reduced oppositional-defiant symptoms. Better impulse control (these were all ADHD children) and/or decreased sympathetic arousal (common to all intermittent explosive aggression) are plausible explanations.