Abnormal Neurochemical Transmissions

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Scientists can't measure the biochemicals that influence the brain's neural transmissions directly. Imbalances in these chemicals can be inferred, however, from reduced numbers of neurotransmitter metabolites in the urine and blood, from differences in cerebrospinal fluid, and from observing how drugs that alter brain chemistry subsequently affect attention, learning, and behavior.

Oddly enough, inattention and hyperactive-impulsive behavior are known to be related to brain underarousal rather than overarousal. When these children talk, read, or engage in activities that require focused attention, they don't experience the same degree of increase in blood flow or glucose utilization in the brain that normally supports these activities. Underarousal also means a diminished supply of the chemicals needed to inhibit activity. As a result, these individuals can't activate attention to high enough levels to focus attention, and they can't activate inhibitory mechanisms to screen out distractions. Once something has grabbed their attention, they can't stop themselves from paying attention or responding.

If underarousal is the problem, then stimulants should be the solution. In a majority of cases, stimulants do help. Many children with any of the three forms of ADHD focus attention better, concentrate, memorize better, are less restless, and refrain from mentally, physically, or verbally responding to irrelevant diversions when they take stimulant medication. The medication seems to heighten the sensitivity of the brain's sensory and attending systems to incoming stimuli, thereby

The most common stimulants used to deal with the symptoms of ADHD are Ritalin (methlyphenidate), Adderall (a combination of amphetamine and dextroamphetamine), CyIert (magnesium pemoline), and Dexadrine (dextroamphetamine). Seventy to 80 percent of children receiving stimulant medication appear to improve to some degree.

As beneficial as these medications are, they have side effects, including insomnia, decreased appetite, weight loss, irritability, lethargy, and abdominal pain, though these tend to diminish within a few weeks. Also observed at times are headaches, drowsiness, sadness, nausea, nightmares, pallor, increased pulse and blood pressure, apathy, a serious facial expression and hollows under the eyes, fearfulness, a dazed appearance, anxiety, and increased talkativeness. Stimulants can induce Tourette's syndrome in individuals at risk. Despite concerns expressed by parents, only one long-term study has documented a link between taking stimulants and substance abuse as an adult. Some growth and weight suppression may occur for a time, but the child does eventually reach his or her expected height and weight. Until recently, "drug holidays" were recommended during school vacations to encourage growth rebound. Because it was found that growth eventually catches up, however, many experts now recommend that children should remain on medication all the time, with drug holidays being given only to teenagers showing serious stimulant-associated growth delays. They reason that it is important for the child to be thinking and behaving as intelligently as possible, as often as possible, even when on vacation. After all, learning does not occur only in the classroom.