ADHD stands for attention deficit hyperactivity disorder. It is a medical condition. A person with ADHD has 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 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.