Attention-deficit hyperactivity disorder (ADHD) is more often diagnosed in children. That might make you wonder if people grow out it as they reach adulthood. ADHD is a neurodevelopmental disorder that involves difficulties focusing attention (for study or work) and/or sitting still or keeping impulsive actions in check. This means people with ADHD are different and the differences are there for life. But development is a dynamic process because people change, mature and develop their skills. If people have ADHD, the way it affects them can change over time too.