Attention-deficit/hyperactivity disorder (ADHD) is a disorder that starts in early childhood and may continue into adulthood. Symptoms include a combination of persistent problems, such as difficulty paying attention, hyperactivity and impulsive behavior. Adult ADHD can lead to unstable relationships, poor work or school performance, low self-esteem, and other problems. Adults may also present with decreased hyperactivity but struggles with impulsiveness, restlessness and difficulty paying attention may continue.