Attention Deficit Hyperactivity Disorder, otherwise known as ADHD, is a common and often persistent disorder in children. Nearly 3% to 5% of elementary-age children are diagnosed with this disorder. Children with ADHD have behavioral problems including being hyperactive, easily distracted, and impulsive, causing emotional, academic, and social problems. As one of the most common disorders in childhood, ADHD has more published studies on it and its variants than any other childhood disorder. Much is still unknown about ADHD. The correct classification of ADHD is still undecided, however, over the past 60 years different terms have been used to describe the disorder. Some include: minimal brain dysfunction, attention deficit disorder, and hyperkinetic impulse disorder. Classifying ADHD can become complicated when scientific research suggests that several behaviors are directly linked to ADHD, but several pieces of research suggest that these behaviors should be independently classified as ADHD. The hallmark characteristics of ADHD are inattention, hyperactivity, and impulsivity. Inattention means lack of attention. A child with symptoms of inattention may have difficulty listening and following directions or staying organized. Hyperactivity describes when a child is unusually and effortlessly excited. Short attention span and strong emotions describe a hyperactive person. Finally, impulsivity occurs when a person carries out a behavior without first thinking about the consequences. Impulsivity can be behavioral, as in the things a person does, or cognitive, as in the way a person thinks and makes choices. A child with ADHD may have difficulty at home, at school, and with friends. At home a child may have trou...... middle of paper ......ed. Drug and alcohol rates are slightly higher in adolescents with ADHD. The lack of comorbidities and family conflicts in a child's life tends to help them function better in adolescents. The main subtypes of ADHD are distinct. Research shows that they may have different etiologies and responses to treatment. Keeping in mind that there is significant overlap with learning disabilities, compliance disorder, and oppositional defiant disorder, ADHD alone without comorbidity is being studied in hopes of providing more information than the comorbid diagnosis. The specific, current definition of ADHD may not be necessary due to the two distinct disorders that occur with the disorder. Children who show early symptoms of ADHD may have different outcomes depending on the situation, age of onset, persistence, and severity of risk factors.