Although the debate over the high increase in the number of children (and adults) being diagnosed with ADHD may continue, there is certainly many reasons why this increase has occurred. While none of these reasons alone may account for the increase, together they may answer the question.
"Attention Deficit/Hyperactivity Disorder: Data & Statistics", Last reviewed 2009, March 13, Division of Human Development, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention
"Myths and Facts About ADHD", Last Reviewed 2007, Feb 19, Reviewed by Rosemary Tannock, PhD, Peter Chaban, M.A., AboutKidsHealth.org
"Has There Been an Increase in ADHD?", 2006, Jan 27, Jeanette C. Ramer, M.D., Penn State University