Do children diagnosed with attention deficit/ hyper-activity disorder (ADHD) have smaller brains than children without this condition? This question was the topic of a research study described in the paper “Developmental Trajectories of Brain Volume Abnormalities in Children and Adolescents with Attention Deficit/ Hyperactivity Disorder” (Journal of the American Medical Association [2002]: 1740– 1747). Brain scans were completed for 152 children with ADHD and 139 children of similar age without ADHD. The researchers wanted to see if the resulting data supported the claim that the mean brain volume of children with ADHD is smaller than the mean for children without ADHD.