Attention deficit hyperactivity disorder (ADHD) is a mental health disorder that can cause above-normal levels of hyperactive and impulsive behaviors. People with ADHD may also have trouble focusing their attention on a single task or sitting still for long periods of time. Both adults and children can have ADHD.A chronic condition including attention difficulty, hyperactivity and impulsiveness.ADHD often begins in childhood and can persist into adulthood. It may contribute to low self-esteem, troubled relationships and difficulty at school or work.Symptoms include limited attention and hyperactivity.Treatments include medication and talk therapy.