In the United States alone, an estimated 4.5 million children ages 5 to 17 have been diagnosed with attention deficit hyperactivity disorder, according to the Centers for Disease Control and Prevention, and rates of diagnosis have risen 3 percent a year between 1997 and 2006.
Yet it is unclear what
is causing th
New research is investigating many avenues.
One of them is environmental factors such as pesticides and allergens.