Abnormal Neurochemical Transmissions (page 2)
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.
Not all children respond to stimulant medication; some 20 to 30 percent show no effect or actually get worse. Moreover, drug dosage is an issue. Children differ regarding the best dosage for optimal thinking. Drug dosage should be decided based on optimal school productivity and learning, even if hyperactivity and other disruptive behaviors are not quite alleviated. In general however, both learning and behavior will improve as standard dosages increase.
Another concern about dosage is that attention, thinking, and behavior seesaw as short-acting drugs reach their peak effect within 1 or 2 hours after taking the medication, and wear off about 2 or 3 hours later. Moreover, at times these children experience a rebound effect as the stimulant wears off, becoming even more active and irritable than they were before taking the medication. If rebound occurs around bedtime, the child may require another dose to calm down enough to permit sleep. Longer-acting slow-release agents (up to 8 hours) help avoid this 4-hour up-and-down cycle, though their effectiveness may not be as powerful. When individuals do not respond favorably to stimulants, physicians have found that tricyclic antidepressants, the antihypertensive clonidine, or monoamine oxidase inhibitors can be effective for some.
Studies prove that stimulant medication can significantly improve attention span, activity level, motor performance, and productivity, accuracy, and persistence in the classroom. However, stimulant medication has been associated with only modest improvements in long-term academic achievement levels and social adjustment.
Stimulant Medication and Attention Span
Attention span does increase for the majority of children who take stimulants, as evidenced by physiological and behavioral measures such as greater brain wave height and frequency, greater cerebral blood flow, heightened reflectivity, reduced impulsivity, and faster reaction time and "hit rate" when required to spot things (such as number 9's flashed on a computer screen). One researcher, noting improvements in impulse control, concentration, and planning, commented that with medication hyperactive children are better able to "stop, look, and listen." Intelligence test scores have been shown to increase by about 15 percentile points in children taking these drugs because, once their attention is channeled, they can make better use of their problem-solving capabilities and past knowledge.
Stimulant Medication and Activity Level
Children taking stimulants are better able to sit still in structured situations that demand paying attention; their in-seat wiggling and foot wagging also decrease. By contrast, when they are not required to focus in a sustained manner on a task, such as on the playground or in the lunchroom, these children's activity level is only sometimes reduced.
Stimulant Medication and Motor Performance
Children show a remarkable improvement in fine- and gross-motor coordination when they take stimulant medication, including reaction time, speed and quality of copying, performing mazes, and balancing. It appears that the drug has a direct effect on the metabolic and neural mechanisms that control and speed up motor responses after the brain has evaluated information, searched its memory, and decided on a course of action.
Stimulant Medication and Academic Achievement
On average across studies, children taking stimulant medication show about a 15 percentile point gain on standardized reading and spelling tests, though not in mathematics. In the classroom, as much as 25 to 40 percent improvement in accuracy, quantity, and speed of completing daily assignments are common, as are improvements in quiz grades. Moreover, persistence is better on frustrating tasks and on memory tasks (such as memorizing word pairs). The improvements in daily productivity and proficiency certainly are notable, though gains on standardized tests remain only modest.
Stimulant Medication, Behavior, and Long-Term Adjustment
Over time, hyperactive children do calm down. They no longer run away from their mothers in the grocery store, rip boxes off the shelf, or break grandma's best china, but their minds continue to wander. Said one adolescent, "My mind is like a television set on which someone is always changing the channels." Fidgetiness (e.g., pencil tapping), restlessness (e.g., leg wagging), impulsivity, speaking out of turn, and doing something reckless without thinking first are common.
A number of studies have shown that stimulants can suppress demanding, antisocial, aggressive, disruptive, and noncompliant behaviors, so that home and school become more manageable, less negative, and less demanding of adult supervision, guidance, admonition, and commands. Peer acceptance also improves. Despite improvements in restlessness, crying, temper outbursts, distractibility, excitability, frustration and pouting, sadly the hyperactive child's reputation for chaos sticks with him or her. Even after a few years on medication, the hyperactivity and inattention continue to set the child apart from his or her peers. These children tend to have few friends, engage in more antisocial behavior, lack ambition, are rebellious and aggressive, fail in school, have poor self-concepts, and are sad. Many are hard to discipline and end up in trouble with the law. Perhaps all those years of being told to "sit down and mind your own business" take their toll. Their reputation makes it difficult to turn around others' negative expectations, especially that of peers. It is no wonder that these youngsters continue to have difficulty negotiating their social worlds, especially when it comes to friendship and intimacy.
The behavioral patterns of the hyperactive-impulsive ADHD child are particularly difficult to modify. Medication alone has more powerful effects on behavior than any other intervention. Nevertheless, no studies have shown peer relations or emotional adjustment to be any better for youngsters who have been on medication several years than for those who have never taken stimulants. It seems that stimulant medication may create greater readiness to adapt socially because adverse behaviors have diminished, yet more than medication is needed to generate long-lasting change in behavior and friendships. Studies have found that a combination of medication and behavior modification, and sometimes cognitive self-control strategy training, social skills training, or attribution training (learning to assume responsibility for the consequences of one's actions) is the most effective intervention. One example of a behavior modification intervention is for the teacher to use a remote control to add points to a monitor on the child's desk when the child is on task. The teacher and student mutually set a goal and the reward for meeting that goal. These types of interventions are not nearly as effective when used alone as when used in combination with stimulant medication. The child needs to be in a more ready state to learn, and the environment needs to be appropriately structured to encourage positive change by systematically teaching these youngsters alternatives Tor coping with problematic situations.
Overactive Inhibitory Mechanisms and Hypoactivity
In contrast to the child with ADHD, hypoactive youngsters seem to suffer from overactive central nervous system inhibitory mechanisms. Therefore, stimuli that would usually grab a child's attention get screened out. These children's sluggishness shows improvement with sedatives, which quiet the overactive inhibitory mechanisms and allow more stimuli to come to their attention.
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