More U.S. children today have developmental disabilities like autism and ADHD than a decade ago, though improved recognition may be a major reason, according to a government study. Researchers found that between 2009 and 2017, the percentage of U.S. children and teens with a developmental disability rose from just over 16% to nearly 18%. Increases in ADHD (attention deficit hyperactivity disorder) and autism spectrum disorders accounted for most of the change.