The symptoms of ADHD include inattention and/or hyperactivity and impulsivity. These are traits that most children display at some point or another. But with ADHD, which stands for attention-deficit hyperactivity disorder, or what was referred to as ADD -- attention deficit disorder -- the symptoms are inappropriate for the child's age.

ADHD is common in children and teens. But adults also can have ADHD. With ADHD in adults, there may be some variation in symptoms. For instance, an adult may experience restlessness instead of hyperactivity. In addition, adults with ADHD consistently have problems with interpersonal relationships and employment.