Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental (related to brain function) condition that is usually diagnosed in childhood. It can last into adulthood. Symptoms include difficulty staying focused or paying attention, excess motor activity (eg, fidgeting), and difficulty controlling impulsive behavior. Although most children have these problems some of the time, the diagnosis is made when these symptoms are more severe and persistent than is expected for the child's age and developmental level. It is important to know that ADHD is a biological condition and not due to poor parenting or a child having bad behavior on purpose. ADHD has different subtypes. Some people have hyperactivity and impulsivity as well as trouble paying attention; other people have mostly symptoms of inattention. Although they may sit quietly, such individuals are not paying attention when they need to, such as in school or while doing homework. Among these people, the diagnosis of ADHD may be missed or delayed.