Until recently, people with ADD were considered stupid and in some cases un-teachable. Famous people including Newton, Leonardo da Vinci and Einstein have been suspected of having ADD or ADHD. ADD is a little-understood but surprisingly common brain imbalance. The disorder is genetic, according to some researchers, and it usually manifests itself first as childhood hyperactivity. But as the physical restlessness wears away during puberty, leaving mainly the attention span symptoms, the syndrome becomes harder to spot. Adult ADD is marked not only by a short attention span but also by a multitasking mind. ADHD, once called hyperkinesis or minimal brain dysfunction, is one of the most common mental disorders among children. It affects 3 to 5 percent of all children, perhaps as many as 2 million American children. Two to three times more boys than girls are affected. On the average, at least one child in every classroom in the United States needs help for the disorder. ADHD often continues into adolescence and adulthood, and can cause a lifetime of frustrated dreams and emotional pain as well as a distorted self-image.Isaac Newton entered college at the age of 18 and failed to distinguish himself in any way. He was extremely forgetful, had a habit of working very late and missing his meals, and had trouble controlling his impulsive nature. On the other hand, he did manage to invent calculus and rewrite physics from the ground up, making almost every physicist or mathematician who has ever lived look like a complete simpleton in comparison. The most famous of renaissance men, Leonardo da Vinci possessed great mathematical ability and made innumerable of creative, brilliant observations about the physical world. He was an underachiever, leaving a body of work that was small in proportion to his ability. He left jobs unfinished, and he moved impulsively from one occupation to another. He was so strongly afflicted as well as inspired that he carried a notebook with him so he could record a reasonable percentage of the ideas that poured into his mind during the course of a day. A more recent scientist, Albert Einstein often lost the key to his apartment and had to wake his landlady in the middle of the night. In spite of his intelligence, he was denied admission to college because he failed biology and math. He said he had to be very careful when shaving because so many inspirations would come to him at this time, that he worried that the shock of a blast of insight would cause him to cut himself.