a behavioral syndrome characterized by inattention and distractibility, restlessness, inability to sit still, and difficulty concentrating on one thing for any period of time. ADHD most commonly occurs in children, though an increasing number of adults are being diagnosed with the disorder. ADHD is three times more common in males than in females and occurs in approximately 3 to 6 percent of all children. Although behaviours characteristic of the syndrome are evident in all cultures, they have garnered the most attention in the United States, where ADHD is the most commonly diagnosed childhood psychiatric disorder.
It was not until the mid-1950s that American physicians began to classify as “mentally deficient” individuals who had difficulty paying attention on demand. Various terms were coined to describe this behaviour, among them minimal brain damage and hyperkinesis. In 1980 the American Psychiatric Association (APA) replaced these terms with attention deficit disorder (ADD). Then in 1987 the APA linked ADD with hyperactivity, a condition that sometimes accompanies attention disorders but may exist independently. The new syndrome was named attention-deficit/hyperactivity disorder, or ADHD.
ADHD does not have easily recognizable symptoms or definitive diagnostic tests. Children and adults are diagnosed with ADHD if they persistently show a combination of traits including, among others, forgetfulness, distractibility, fidgeting, restlessness, impatience, difficulty sustaining attention in work, play, or conversation, or difficulty following instructions and completing tasks. According to criteria issued by the APA, at least six of these traits must be present “to a degree that is maladaptive,” and these behaviours must cause “impairment” in two or more settings—e.g., at school, work, or at home. Inattention predominates in some cases, hyperactivity in others, and in a combined type of ADHD the two are present together. Studies have shown that more than a quarter of children with ADHD are held back a grade in school, and a third fail to graduate from high school. The learning difficulties associated with ADHD, however, should not be confused with a deficient intelligence.
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