Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition that affects around 7% of children and 2.5% of adults. ADHD causes difficulties holding and sustaining attention over periods of time. People with ADHD also experience hyperactivity and high levels of impulsiveness and arousal. This can make it difficult to plan, coordinate and remain engaged in tasks. ADHD is linked to problems at work, school and home, and to higher rates of mental illnesses such as anxiety.