Mostly, unfortunately, funded by Pharmaceutical companies - ADHD Nation: Children, Doctors, Big Pharma, and the Making of an American Epidemic ( https://www.amazon.com/ADHD-Nation-Children-American-Epidemi... ):

> More than 1 in 7 American children get diagnosed with ADHD—three times what experts have said is appropriate—meaning that millions of kids are misdiagnosed and taking medications such as Adderall or Concerta for a psychiatric condition they probably do not have. The numbers rise every year. And still, many experts and drug companies deny any cause for concern. In fact, they say that adults and the rest of the world should embrace ADHD and that its medications will transform their lives.