Attention deficit hyperactivity disorder (ADHD) is a condition in which characterized by inattention, hyperactivity and impulsivity. ADHD is most commonly diagnosed in young people, according to the Center for Disease Control and Prevention (CDC). An estimated 9% of children between ages 3–17 have ADHD. While ADHD is usually diagnosed in childhood, it does not only affect children. An estimated 4% of adults have ADHD. With treatment, most people with ADHD can be successful in school, work and lead productive lives. Researchers are using new tools such as brain imaging to better understand the condition and to find more effective ways to treat and prevent ADHD.