ADHD, the most common neurobehavioral disorder in childhood, affects 4 to 12 percent of U.S. school-age children. Symptoms include short attention span, impulsive behavior and difficulty focusing.

• ADHD注意力缺陷过动症,这个儿童期最常见到的神经行为异常，在美国学龄儿童佔百分之4到百分之12，症状有注意期间短、冲动、不容易专心。