The actual prevalence of attention-deficit/hyperactivity disorder (ADHD) remained relatively stable over the course of a decade, even in the face of increases in clinical diagnoses, according to researchers who published their findings in The Journal of Child Psychology and Psychiatry...Data on 19,271 9-year old twins (50.6% boys) were extracted between 2004 and 2014 from the ongoing population-based Child and Adolescent Twin Study in Sweden and analyzed for ADHD traits using the Autism-Tics, ADHD and other Comorbidities (A-TAC) inventory, via parental report.