The Journal of the American Medical Association reports that too much screen time may boost teens' risk of attention-deficit/hyperactivity disorder symptoms, according to a study of 2,587 10th-graders in Los Angeles. Findings show that students in the study who were high frequency users of 7 or 14 digital media platforms were more than twice as likely to develop ADHD symptoms as students who didn't have a high frequency use rate of any of the online social activities.