There is a very interesting article about the results of a study showing that kids with ADHD have slower brain development in the higher functions of the brain than non adhd kids. Its further proof that this isn't a made up condition as certain quacks out there claim.
http://content.time.com/time/health/article/0,8599,1683069,00.html
http://content.time.com/time/health/article/0,8599,1683069,00.html