Attention-deficit/hyperactivity disorder (AD/HD) is characterized by developmentally inappropriate levels of inattention, impulsivity, and hyperactivity. AD/HD is a neurobiological disorder that affects 3 to 7 percent of school-age children. Until relatively recently, it was believed that children outgrew AD/HD in adolescence as hyperactivity often diminishes during the teen years. However, it is now known that AD/HD nearly always persists from childhood through adolescence and that many symptoms continue into adulthood. In fact, current research reflects rates of roughly 2 to 4 percent among adults. Although individuals with this disorder can be very successful in life, without identification and proper treatment, AD/HD may have serious consequences, including school failure, family stress and disruption, depression, problems with relationships, substance abuse, delinquency, risk for accidental injuries and job failure. Early identification and treatment are extremely important. Medical science first documented children exhibiting inattentiveness, impulsivity and hyperactivity in 1902. Since that time, the disorder has been given numerous names, including minimal brain dysfunction, hyperkinetic reaction of childhood and attention-deficit disorder with or without hyperactivity. With the Diagnostic and Statistical Manual, fourth edition (DSM-IV) classification system, the disorder has been renamed attention-deficit/hyperactivity disorder, or AD/HD. The current name reflects the importance of the inattentioTHE SYMPTOMS.