A 9-Year Follow-Up of Attention-Deficit/Hyperactivity Disorder in a Population Sample.

Prior follow-up studies of attention-deficit/hyperactivity disorder (ADHD) have mostly been from North America. They have provided a good deal of information about ADHD, but whether these results generalize to population samples and to other countries is not certain. Most prior studies have also not assessed predictors of possible new onsets of ADHD in non-ADHD youth or the validity of subthreshold forms of the disorder.