Have We Been Thinking About A.D.H.D. All Wrong?

Over the past three decades, A.D.H.D. diagnoses in the U.S. have been climbing steadily, and so have prescriptions for the medication to manage the symptoms. As the field booms, some longtime researchers are starting to question whether much of the fundamental thinking around how we identify and treat the disorder is wrong. Paul Tough, a contributing writer for The New York Times Magazine, explains.