Fan Casting Attention Deficit... Ooh, Shiny! in Sort by Tropes

In media, the symptoms of attention deficit disorders tend to be exaggerated to the point of absurdity. Sufferers seem to be on a constant caffeine high. They are unable to maintain focus on anything for more than a few minutes before getting distracted by a shiny object, hence the trope title. There are a few simple reasons for this trope. First is a rampant misunderstanding about what ADHD actually is (in which case you should go do some research), resulting in the oversimplification and exaggeration. Second, it's much funnier to have a character who just fidgets and spaces out occasionally without having to worry about the realism of adding other dimensions to their personality.