Then there is the intensity of the reactions to consider. In children and adults alike, such symptoms can range from “very mild to very severe,” RachBeisel says. Having ADHD means that a person frequently exhibits these tendencies across multiple situations, including school, home, or work, impairing the ability to complete tasks. Craig Surman, a physician and psychiatrist who runs the adult ADHD research program at Massachusetts General Hospital, explains that though the impulsive and hyperactive nature of the disorder usually diminishes in adulthood, “the inattentive traits often persist.”