"In 2003, 7.8% of 4- to 17-year-olds in the US were were diagnosed with ADHD, according to the National Survey of Children’s Health. By 2011, that figure had reached 11% of students, with 20% of high-school boys diagnosed with the condition.
Explanations for the dramatic spike in ADHD cases range from increased awareness of the condition and improvements in how it is diagnosed, to the bottom-line bonanza for pharmaceutical companies and kids looking for pharmacological help to focus on standardized tests. Or it could be that the increase in school-accountability measures has led low-performing schools to identify more ADHD students to get more funding (pdf).
Jeffrey P. Brosco, a doctor and a professor of clinical pediatrics at the University of Miami Miller School of Medicine, has another theory: he thinks the dramatic rise in academic standards since the 1970s may be responsible."