attention deficit hyperactivity disorder (ADHD), formerly called hyperkinesis or minimal brain dysfunction, a chronic, neurologically based syndrome characterized by any or all of three types of behavior: hyperactivity, distractibility, and impulsivity. Hyperactivity refers to feelings of restlessness, fidgeting, or inappropriate activity (running, wandering) when one is expected to be quiet; distractibility to heightened distraction by irrelevant sights and sounds or carelessness and inability to carry simple tasks to completion; and impulsivity to socially inappropriate speech (e.g., blurting out something without thinking) or striking out. Unlike similar behaviors caused by emotional problems or anxiety, ADHD does not fluctuate with emotional states; sleep deprivation may also cause symptoms in children that resemble those of ADHD. While the three typical behaviors occur in nearly everyone from time to time, in those with ADHD they are excessive, long-term, and pervasive and create difficulties in school, at home, or at work. ADHD is usually diagnosed before age seven. It is often accompanied by a learning disability.
The cause of ADHD is unknown, although there appears to be a genetic component in some cases. Intake of sugars is no longer considered to be a factor. Some studies suggest that although food additives, such as colorings, do not cause symptoms in the general population, they may aggravate hyperactivity in some susceptible individuals. It has been shown that people with ADHD have less activity in areas of the brain that control attention. Treatment usually includes behavioral therapy and emotional counseling combined with medications such as methylphenidate hydrochloride (Ritalin) or dextroamphetamine (Dexedrine) that correct neurochemical imbalances in the brain; over the long term, however, such medications do not appear to offer any benefits. Symptoms may decrease after adolescence, although they often persist into adulthood.