Attention deficit hyperactivity disorder, also known as ADHD, is a chronic, developmental condition that makes it difficult for children to control their attention and behavior. The disorder, which is characterized by levels of inattention, hyperactivity, and impulsivity that are developmentally inappropriate, affects 8 to 12 percent of all school-age children—or at least one student in every classroom in the United States.
While every child misbehaves or acts out now and again—fidgeting in science class, say, or throwing a temper tantrum in the grocery store—those with ADHD have serious, recurrent problems that continually interfere with daily life. Although symptoms of the disorder vary by individual and can range from mild to severe, some of the most common signs are: difficulty focusing in a variety of situations, problems getting organized, not listening when spoken to, having trouble sitting still or waiting in line, and constantly interrupting others.
ADHD is more widespread among males than females; in fact, two to three times as many boys as girls are diagnosed with the disorder. However, it's important to remember that females and gifted children with ADHD are underidentified populations. In adult populations, men and women have ADHD in about equal numbers.
ADHD symptoms continue into adulthood for more than 60 percent of children with the condition. Adults who are not treated may be plagued by frustration and social difficulties, by employment problems, and by a resulting blow to their self-esteem and sense of being effective in their daily lives. Among the behaviors that may stem directly from ADHD are chronic lateness, forgetfulness, anxiety, difficulty organizing, difficulty controlling anger, and impulsiveness.
The good news is that ADHD is now one of the most studied childhood conditions. While there is currently no cure, there are numerous treatment options available—as well as frequent advances in both drug and behavioral therapies—all of which can control symptoms and help patients live normal lives. The end result is that it is easier than ever before to manage ADHD over the course of a child or adult's lifetime, and the outlook for those who receive intervention and treatment is quite promising.
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The causes of ADHD are still unknown, but the majority of evidence indicates that the condition has a neurological basis. Research suggests that it results from an irregularity in certain neurotransmitters, the chemicals that send information between cells, directing behavior. One recent study indicated a link between a person's ability to pay continued attention and the level of activity in the brain, finding, for example, that the rate at which the brain uses glucose—its main source of energy—is lower in people with ADHD.
Many parents worry that their poor parenting has caused their child's ADHD. While it is true that behavior problems and low self-esteem might be made worse when a parent constantly reacts to the child with anger and frustration, there is not evidence to support the notion that parenting causes the condition in the first place. Some research has suggested a possible link to smoking and the use of alcohol during pregancy or to high levels of lead in a young child's body in some instances, but these cases are relatively rare. There is no evidence that the disorder is triggered by eating sugar or food additives or by allergies or immunizations.
In rare cases, research has shown that extremely severe head injuries may lead to ADHD.
While the causes of ADHD are not well understood, experts believe that there is a biological explanation for the condition. Brain-scan studies at the National Institute of Mental Health have noted that the volume of matter in several key parts of the brain are 3 to 4 percent smaller in children with ADHD than in other children. These key areas include the frontal lobes of the cerebrum, which are responsible for problem solving, planning, and impulse control; the cerebellum, which regulates motor coordination; and the caudate nucleus, a structure in the basal ganglia that organizes information sent to the frontal lobes from other areas of the brain.
The researchers also found that the volume of white matter (the fibers that connect and transmit electrical signals between the regions of the brain) in study subjects who had been treated with medication equaled that of the control group, while those who had never been medicated had an unusually small volume of white matter. Brain scans are useful for research, but they cannot be used to reliably diagnose the disorder.
Although its causes remain a mystery, ADHD is thought to be hereditary. If one or both parents have the disorder, their children have a higher probability of showing symptoms of the condition. (Actually, it is often the child's diagnosis that alerts the parent to his or her own need for assessment.) Studies of twins have supported the notion that genes play a big part in determining who is affected.
Last reviewed on 08/18/2008
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