Attention deficit hyperactivity disorder (ADHD) is a behavioral condition in which people have difficulty paying attention, may be more active than normal, and tend to act without thinking. This common disorder begins in early childhood and can continue into adulthood.

The exact cause is not clear, although the disorder tends to run in families, so a genetic factor is likely. Treatment is specific to each person's symptoms and problems and may include medications, behavior management, and counseling.