Attention deficit hyperactivity disorder, or ADHD as it is commonly known, has been extensively researched by doctors and psychologists over the past decades. For a very long time, it was thought to be a neurological disorder that only affected the youngest children. Now there is no doubt that in more than two-thirds of children with ADHD, the disorder syndrome will also cause specific problems in adulthood. The most common symptoms include poor concentration, impulsivity and hyperactivity, referred to as hyperactivity. ADHD is also a problem with judging the importance of stimuli and blocking out irrelevant information.