A new global study involving the University of Adelaide has found that children who are the youngest in their classroom are more likely to be diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) than their older classmates. The research, led by Curtin University and published in the Journal of Child Psychology and Psychiatry, systematically reviewed studies that examine the relationship between a child’s age relative to their classmates and their chances of being diagnosed with, or medicated for, ADHD.