Attention deficit hyperactivity disorder, more commonly known as ADHD, is a disorder that affects a persons attention span and how long that person can focus on a certain task. Many people with ADHD take medications that help curb the effects of the disorder and allow them to remain focused on what they are doing for a longer time span. ADHD is usually diagnosed in children and can follow them through their adult lives. In some cases the disorder can show reduced signs as the person ages. Children with ADHD frequently move from one activity to the next very quickly and have a difficult time sitting still for even short time periods.