Attention-deficit/hyperactivity disorder is a chronic condition involving attention difficulty, hyperactivity and impulsiveness. It is a medical condition. Patients suffering from ADHD have differences in brain development and brain activity that affect attention, the ability to sit still, and self-control. ADHD can affect a child at school, at home, and in friendships. It usually begins in childhood and can continue into adulthood. It may add to low self-esteem, troubled relationships and difficulty at school or work. Symptoms include limited attention and hyperactivity. Treatments include medication and talk therapy.