Attention Deficit Hyperactivity Disorder (ADHD)

Attention Deficit Hyperactivity Disorder (ADHD)

Attention Deficit Hyperactivity Disorder (ADHD) 


Is the most commonly diagnosed behavioral disorder of childhood. It affects about 3 - 5% of school aged children. ADHD is diagnosed much more often in boys than in girls. ADHD may run in families, but it is not clear exactly what causes it. Whatever the cause may be, it seems to be set in motion early in life as the brain is developing. Imaging studies suggest that the brains of children with ADHD are different from those of other children.


Depression, lack of sleep, learning disabilities, tic disorders, and behavior problems may be confused with, or appear with, ADHD. Every child suspected of having ADHD should be carefully examined by a doctor to rule out possible other conditions or reasons for the behavior.


Most children with ADHD also have at least one other developmental or behavioral problem. They may also have a psychiatric problem, such as depression or bipolar disorder.


Brain Functioning in ADHD


ADHD is not the result of laziness, poor motivation, low intelligence, disobedience, poor upbringing or selfishness—to name a few. Although having ADHD doesn’t exclude you from having some of these difficulties, these problems do not cause chronic inattention, hyperactivity and impulsiveness—the core symptoms of ADHD. ADHD is a medical disorder, and it can be caused by a number of factors that affect how the brain develops and functions.


Current research indicates the frontal lobe, basal ganglia, caudate nucleus, cerebellum, as well as other areas of the brain, play a significant role in ADHD because they are involved in complex processes that regulate behavior (Teeter, 1998). These higher order processes are referred to as executive functions. Executive functions include such processes as inhibition, working memory, planning, self-monitoring, verbal regulation, motor control, maintaining and changing mental set and emotional regulation.


According to a current model of ADHD developed by Dr. Russell Barkley, problems in response inhibition is the core deficit in ADHD. This has a cascading effect on the other executive functions listed above (Barkley, 1997).


What factors could account for neurological differences in brain development and functioning that could contribute to ADHD?


The main factors studied to date have been: fetal exposure to toxic substances (e.g., alcohol and tobacco) during pregnancy, exposure to lead, trauma to the brain from head injury or illness and differences that could be attributed to heredity. These causes are discussed below.


Heredity as a Cause of ADHD


Heredity is the most common cause of ADHD. Most of our information about the heritability of ADHD comes from family studies, adoption studies, twin studies and molecular genetic research. Family Studies: If a trait has a genetic basis we would expect the rate of occurrence to be higher with the biological family members (e.g., brown-eyed people tend to have family members with brown eyes).


Dr. Joseph Biederman (1990) and his colleagues at the Massachusetts General Hospital have studied families of children with ADHD. They have learned that ADHD runs in families. They found that over 25% of the first-degree relatives of the families of ADHD children also had ADHD, whereas this rate was only about 5% in each of the control groups.


Therefore, if a child has ADHD there is a five-fold increase in the risk to other family members.


Adoption Studies: If a trait is genetic, adopted children should resemble their biological relatives more closely than they do their adoptive relatives. Studies conducted by psychiatrist Dr. Dennis Cantwell compared adoptive children with hyperactivity to their adoptive and biological parents. Hyperactive children resembled their biological parents more than they did their adoptive parents with respect to hyperactivity.


Twin Studies: Another way to determine if there is a genetic basis for a disorder is by studying large groups of identical and non-identical twins. Identical twins have the exact same genetic information while non-identical twins do not. Therefore, if a disorder is transmitted genetically, both identical twins should be affected in the same way and the concordance rate — the probability of them both being affected — should be higher than that found in non-identical twins. There have been several major twin studies in the past few years that provide strong evidence that ADHD is highly heritable.


They have had remarkably consistent results in spite of the fact that they were done by different researchers in different parts of the world. In one such study, Dr. Florence Levy and her colleagues studied 1,938 families with twins and siblings in Australia. They found that ADHD has an exceptionally high heritability as compared to other behavioral disorders. They reported an 82 percent concordance rate for ADHD in identical twins as compared to a 38 percent concordance rate for ADHD in non-identical twins.


Molecular Genetic Research: Twins studies support the hypothesis of the important contribution that genes play in causing ADHD, but these studies do not identify specific genes linked to the disorder. Genetic research in ADHD has taken off in the past five years. This research has focused on specific genes that may be involved in the transmission of ADHD. Dopamine genes have been the starting point for investigation. Two dopamine genes, DAT1 and DRD4 have been reported to be associated with ADHD by a number of scientists. Genetic studies revealed promising results, and we should look for more information about this soon.


Exposure to Toxic Substances as a Cause of ADHD


Researchers have found an association between mothers who smoked tobacco products or used alcohol during their pregnancy and the development of behavior and learning problems in their children. A similar association between lead exposure and hyperactivity has been found, especially when the lead exposure occurs in the first three years.


Nicotine, alcohol, and lead can be toxic to developing brain tissue and may have sustained effects on the behavior of the children exposed to these substances at early ages. However, it is unlikely that such exposure accounts for differences in brain development in the vast majority of children and adolescents with ADHD.


Injury to the Brain from Trauma, Brain Tumors, Strokes or Disease.


Injury to the brain can be the result of trauma (serious blow to the head), brain tumor, stroke or disease. These factors can cause problems with inattention and poor regulation of motor activity and impulses. While such circumstances can result in a diagnosis of ADHD, the occurrence of such is atypical.


What Does Not Cause ADHD?


  • Diet: In the 1970’s it became popular to view ADHD as resulting from allergies or sensitivities to certain food substances. However, much of the research done over the past two decades was unable to support the claim that diet played a significant role in causing ADHD. Despite this, the popular media continues to discuss the role of food in ADHD, particularly that sugar may cause children to become hyperactive and impulsive. There is no research to back up this claim. In fact, Dr. Mark Wolraich and his colleagues found no significant effects of sugar on either behavior or learning in children.
  • Hormones: No studies have found any significant connection between problems with hormone functioning and hyperactivity or ADHD.
  • The vestibular system: For a number of years some clinicians have proposed the theory that ADHD and some learning and emotional problems could be the result of problems within the vestibular system of the brain which affects balance. They contend that treatment with anti-motion sickness medicine could correct these problems. This theory is unsupported by scientific research and is inconsistent with what is known about ADHD and the vestibular system.
  • Poor parenting or problems in family life: No studies support the idea that ADHD is the result of poor parenting practices or other family environment variables. While parents of children with ADHD are likely to give more negative commands to their ADHD child and less positive attention, this may be due to the fact that ADHD children are often non-compliant and, therefore, parents are more likely to be more negative in their interaction with them.  Furthermore, the interactions of parents of ADHD children whose behavior was not oppositional were no different than they were from non-ADHD children. It is important to note, however, that symptoms of ADHD and the degree to which such symptoms can impact the child’s functioning, can be reduced by parents who provide appropriate accommodations and interventions.
  • Television: No studies have found any connection between television viewing and ADHD. Nor have any studies indicated that children with ADHD watch more television than do those without ADHD.




There is no single cause for ADHD. Scientists agree that ADHD is a medical disorder affecting the several areas of the brain with the frontal area likely having the greatest involvement. Those areas involved are responsible for certain executive functions that control the regulation of behavior, working memory, thinking, planning and organizing. Heredity is the most common cause of ADHD. This has been confirmed in studies looking at the rates of occurrence of ADHD within families, studies of adopted ADHD children and twin studies.


Molecular genetic research has focused on the specific genes that may be responsible for characteristics of ADHD. Other risk factors for ADHD have to do with factors that can influence brain development and functioning such as exposure to toxic substances in the developing fetus and acquired brain injury due to trauma or disease. Factors such as diet, vestibular dysfunction, television viewing and parenting have not been proven to be causes of ADHD.


The symptoms of ADHD fall into three groups:


  • Lack of attention (inattentiveness).

  • Hyperactivity.

  • Impulsive behavior (impulsivity).


Some children with ADHD primarily have the inattentive type. Others may have a combination of types. Those with the inattentive type are less disruptive and are more likely to not be diagnosed with ADHD.


Inattentive symptoms:


  1. Fails to give close attention to details or makes careless mistakes in schoolwork.
  2. Has difficulty keeping attention during tasks or play.
  3. Does not seem to listen when spoken to directly.
  4. Does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace.
  5. Has difficulty organizing tasks and activities.
  6. Avoids or dislikes tasks that require sustained mental effort (such as schoolwork).
  7. Often loses toys, assignments, pencils, books, or tools needed for tasks or activities.
  8. Is easily distracted.
  9. Is often forgetful in daily activities.


Hyperactivity symptoms:


  1. Fidgets with hands or feet or squirms in seat.
  2. Leaves seat when remaining seated is expected.
  3. Runs about or climbs in inappropriate situations.
  4. Has difficulty playing quietly.
  5. Is often "on the go", acts as if "driven by a motor", talks excessively.


Impulsivity symptoms:


  1. Blurts out answers before questions have been completed.
  2. Has difficulty awaiting turn.
  3. Interrupts or intrudes on others (butts into conversations or games).


Treating ADHD is a partnership between the health care provider, parents or caregivers, and the child.


For therapy to succeed, it is important to:


  • Set specific, appropriate target goals to guide therapy.
  • Start medication and behavior therapy.
  • Follow-up regularly with the doctor to check on goals, results, and any side effects of medications. During these check-ups, information should be gathered from parents, teachers, and the child.


If treatment does not appear to work, the health care provider should:


  • Make sure the child indeed has ADHD.
  • Check for other, possible medical conditions that can cause similiar symptoms.
  • Make sure the treatment plan is being followed.


What educational interventions have been studied and shown to be effective in the treatment of ADHD?


Children with ADHD may require adjustments in the structure of their educational experience, including tutorial assistance and the use of a resource room. Many children function well throughout the entire school day with their peers. However, some patients with ADHD will benefit from a "pull out session" to complete tasks, review specific homework assignments, and develop "management" skills necessary for higher education.


Extended time for class work/tests may be necessary as well as assignments written on the board and preferential seating near the teacher. An IEP (individualized educational program) should be developed and reviewed periodically with the parents. ADHD is considered a disability falling under U.S.


Public Law 101-476 (Individuals With Disabilities Education Act, "IDEA"). As such, individuals with ADHD may qualify for "appropriate accommodations within the regular classroom" within the public-school system. In addition, the Americans With Disabilities Act ("ADA") indicates that secular private schools may be required to provide similar "appropriate accommodations" in their institutions.


What medications are currently being used to treat ADHD?


Psychostimulant medications, including methylphenidate (Ritalin, Metadate, and Concerta), amphetamine (Dexedrine, Vyvanse, and Adderall), and atomoxetine (Strattera, marketed as a "non-stimulant," although its mechanism of action and potential side effects are essentially equivalent to the "psychostimulant" medications), are the most widely researched and commonly prescribed treatments for ADHD.


Numerous short-term studies have established the safety and effectiveness of stimulants and psychosocial (behavioral therapy) treatments for not only alleviating the symptoms of ADHD but also improving the child's ability to follow rules and improve relationships with peers and parents. National Institute of Mental Health (NIMH) research has indicated that the two most effective treatment modalities for elementary-school children with ADHD are a closely monitored medication treatment or a program that combines medication with intensive behavioral interventions (behavior therapy).


In the NIMH Multimodal Treatment Study for Children With ADHD (MTA), which included nearly 600 elementary-school children across multiple sites, nine out of 10 children improved substantially on one of these treatment programs.


Recently the Federal Drug Administration (FDA) has licensed the use of guanfacine as a non-stimulant medication effective in treating ADHD. Both a short-term preparation (Tenex) and a long-term preparation (Intuniv) are available. Unfortunately, 18% of Intuniv users discontinued use of their medication due to side effects, including drowsiness (35%), headache (25%), and fatigue (14%).


Two types of antidepressant medications, the "tricyclic antidepressants" (TCA) (imipramine, desipramine, and nortriptyline) and bupropion (Wellbutrin), have also been shown to have a positive effect on all three of the major components of ADHD: inattention, impulsivity, and hyperactivity. They tend, though, to be considered as second options for the children who have shown inadequate response to stimulant medication or who experience unacceptable side effects from stimulant medication such as tics (uncontrolled movement disorders) or insomnia.


The antidepressants, however, have a greater potential for side effects of their own, such as heart-rate and rhythm changes, dry mouth, headaches, and drowsiness, to name a few. If higher doses are required, bupropion may bring on seizures. The antidepressants, therefore, require more careful monitoring.


For the child who has a combination of ADHD and comorbid conditions such as depression, anxiety disorders, or mood disorders, stimulant medications can be combined with an antidepressant medication very successfully.


Are there standard doses for these ADHD medications?


For most children, stimulant medications are very safe and extremely effective. Research has shown that up to 80% of ADHD children show very good to excellent response to these medications. Improvements in the delivery systems for these medications in the last few years that have allowed the child to frequently only require one dose per day, alleviating the embarrassing "trip to the nurse's office" for a midday dose at school.


Recently, a skin patch (Daytrana, a methylphenidate transdermal system) that, when applied daily, delivers the medication at a carefully controlled rate. The doctor will work with the child and his family to find the best medication, dosage, schedule, and delivery system. This requires careful individualization, since some children respond to one type of stimulant much better than another and each child's daily needs and schedules are so variable.


How long are children on these ADHD medications?


The expected duration of treatment has lengthened during this past decade as evidence has accumulated that benefits extend into adolescence and adulthood. Medication usage during the teen years can become problematic. The natural rebellion and desire for independence can make the adolescent protest against taking a medication. The need for a medication may reinforce anxiety that is common during the teen years in that it reinforces the notion of "I am different" to an age range that craves "fitting in".


As such, parents and physicians must empower the teen to become a partner rather than a mere participant in his/her health. In some circumstances, it may even be necessary to allow the teenager to suffer the effects (academic and social) should he refuse to take medication. It is frequently the case that medication will be required into adulthood, and these years are critically important ones for the adolescent to begin to learn self-management of medication and other issues related to ADHD.


Hasn't the use of stimulant medication become excessive?


While it is certainly true that the prescribing of stimulant medication has increased sharply in the last 15 years, the statistics indicate that this increase coincides with the number of legitimately diagnosed cases of ADHD worldwide. Physicians, and the population in general, have achieved a much greater degree of awareness of and acceptance of the biological nature of ADHD, as well as the dramatic effectiveness of treatment protocols.


Are there differences in stimulant use across racial and ethnic groups?


There are significant differences in access to mental-health services between children of different racial groups, and consequently, there are differences in medication use. In particular, African-American children are much less likely than Caucasian children to receive psychotropic medications, including stimulants, for treatment of mental disorders.


Why are stimulants used when the problem is over-activity?


Recall that the three key components in ADHD are inattention, impulsiveness, and hyperactivity. While the exact nature of the disorder at the brain-cell level is not completely understood, it is felt that the medications work by stimulating the brain cells to make more of the chemicals (neurotransmitters) available that send messages from one brain cell to another. This improved message-sending system enhances the brains ability to pay attention, control behavior and impulses, plan actions, and follow through on schedules.


What are the risks of the use of stimulant medication and other treatments?


Stimulant medications have been successfully used to treat patients with ADHD for more than 50 years. This class of medication, when used under proper medical supervision, has an excellent safety record. In general, the side effects of the stimulant class of medications are mild, often temporary, and potentially reversible with adjustment in dosage amount or interval of administration. The incidence of side effects is highest when administered to preschool-aged children.


Common side effects include appetite suppression, sleep disturbances, and weight loss. Less common side effects include an increase in heart rate/blood pressure, headache, and emotional changes (social withdrawal, nervousness, and moodiness). Patients treated with the methylphenidate patch (Daytrana) may develop a skin sensitization at the site of application.


Approximately 15%-30% of children treated with stimulant medication develop minor motor tics (involuntary rapid twitching of facial and/or neck and shoulder muscles). These are almost always short lived and resolve without stopping the use of medication.


A recent investigation studied the possibility of stimulant medication used to treat ADHD and cardiovascular side effects. Concern focused on a possible association with heart attack, heart-rate and rhythm disturbances, and stroke. At the time of the writing of this article, there is no certainty as to the relationship to these event (including sudden death) when medication is used in a pediatric population screened for prior cardiovascular symptoms or structural pathology.


A positive family history for certain conditions (such as unusual heart-rhythm patterns) may be considered a risk factor. The current position of the American Academy of Pediatrics is that a screening EKG is not indicated before initiation of stimulant medication in a patient without risk factors.


Will children taking these medications for ADHD become drug addicts?


Although an increased risk of drug abuse and cigarette smoking is associated with childhood ADHD, this risk appears due to the ADHD condition itself, rather than its treatment. In a study jointly funded by the NIMH and the National Institute on Drug Abuse, boys with ADHD who were treated with stimulants were significantly less likely to abuse drugs and alcohol when they got older. Caution is warranted, nonetheless, as the overall evidence suggests that people with ADHD (particularly untreated ADHD) are indeed at greater risk for later alcohol or substance abuse.


Because some studies have come to conflicting conclusions, more research is needed to understand these phenomena. Regardless, in view of the substantial, well-established findings of the harmful effects of inadequate treatment or no treatment for a child with ADHD, parents should not be dissuaded from seeking effective treatments because of misconstrued or exaggerated claims about substance-abuse risks.


"Diversion" is the transfer of medication from the patient for whom it was prescribed to another individual. Several large studies have indicated that 5%-9% of grade-school and high-school students and 5%-35% of college-age individuals reported use of non-prescribed stimulant medication. Approximately 16%-29% of students for whom stimulant medications were prescribed reported being approached to give, trade, or sell their medication.


Misuse was more frequently seen in whites, members of fraternities and sororities, and students with a lower GPA. Diversion was more likely with the short-acting preparations. The most common reasons cited for use on non-prescribed stimulants were they "helped with studying", improved alertness, drug experimentation, and "getting high".


ADHD (Attention deficit hyperactivity disorder) is one of the most common disorders of childhood. ADHD occurs two to four times more commonly in boys than girls (male to female ratio 4:1 for the predominantly hyperactive type versus 2:1 for the predominantly inattentive type).


While previously believed to be "outgrown" by adulthood, current opinion indicates that many children will continue throughout life with symptoms that may affect both occupational and social functioning.


The medical community recognizes three basic forms of the disorder:


  • Primarily inattentive: recurrent inattentiveness and inability to maintain focus on tasks or activities. In the classroom, this may be the child who is "spacing out" and "can't stay on track".
  • Primarily hyperactive-impulsive: Impulsive behaviors and inappropriate movement (fidgeting, inability to keep still) or restlessness are the primary problems. Unlike the inattentive ADHD-type child, this individual is more often the "class clown" or "class devil" - either manifestation leads to recurrent disruptive problems.
  • Combined: This is a combination of the inattentive and hyperactive-impulsive forms.


The combined type of ADHD is the most common. The predominantly inattentive type is being recognized more and more, especially in girls and in adults. The predominantly hyperactive-impulsive type, without significant attention problems, is rare.


We are still learning about ADHD, and experts' ideas of the disorder are still being shaped. Some believe, for example, that the term "attention deficit" is misleading.


They maintain that people with ADHD are actually able to pay attention too well, rather than too little, but have difficulty regulating their attention, leaving them unable to properly focus.


Others have trouble ignoring irrelevant details and/or focus so intensely on specific details that they miss the bigger, more important, picture.


Many ADHD sufferers cannot shift gears from one thing to another when they need to, leaving them unable to focus on what needs to be done. Extreme difficulty getting a child to stop playing a video game to come to dinner is a common example.


Contrary to some media accounts, attention disorders are not new. Childhood hyperactivity was a focus of interest in the early 1900s. Today, hyperactivity, impulsivity, and inattention are the focus, but disability related to hyperactivity and distractibility has been alluded to throughout medical history. Historical figures of diverse backgrounds and accomplishment have demonstrated behavior compatible with ADHD. Mozart composed and remembered entire musical compositions but disliked the tedious task and attention to detail necessary when transcribing to paper.


Einstein would spend hours and even days sitting quietly in a chair doing "thought experiments", including complex series of mathematical calculations and revisions. Ben Franklin failed in school due to his perfectionist and impulsive behaviors. He later mastered five languages (self-taught) and was highly respected as an author, scientist, inventor, and businessman (publisher). What is new is the greater awareness of ADHD thanks to rapidly mounting research findings.


In the United States, ADHD affects about 3%-10% of children. Similar rates are reported in other developed countries such as Germany, New Zealand, and Canada.


In most cases, the unusual behaviors are noticed by the time the child is about 7 years old, although ADHD is occasionally diagnosed in teenagers or young adults. Children with ADHD are often noted to be emotionally delayed, with some individuals having a delay in maturity of up to 30% when compared with their peers. Thus a 10-year-old student may behave like a 7-year-old; a 20-year-old young adult may respond more like a 14-year-old teenager.


Boys are more likely than girls to be diagnosed with ADHD. At one time, the ratio of boys to girls with ADHD was thought to be as high as 4:1 or 3:1. This ratio has been decreasing, however, as more is known about ADHD. For instance, greater recognition of the inattentive form of ADHD has increased the number of girls diagnosed with the disorder.


People identified with ADHD in adulthood are almost as likely to be women as men, suggesting that we may have been missing the diagnosis in many young girls. Approximately one-quarter of those with ADHD have significant learning disabilities, including problems with oral expression, listening skills, reading comprehension, and mathematics.


There is disagreement over whether ADHD persists as children grow into adults.


Some believe that most children simply grow out of ADHD. Others believe that ADHD persists into adulthood. Estimates of the number of children with ADHD who continue to have the disorder in adulthood range from 30%-80%.


Hyperactive symptoms may decrease with age, usually diminishing atpuberty, perhaps because people tend to learn how to gain greater self-control as they mature. Inattention symptoms are less likely to fade with maturity and tend to remain constant into adulthood. As we learn more about ADHD, certain subtypes will likely be found to cause more adult dysfunction than others.


People with ADHD are much more likely than the general population to have other related conditions such as learning disorders, restless legs syndrome, ophthalmic convergence insufficiency, depression, anxiety disorder, antisocial personality disorder, substance abuse disorder, conduct disorder, and obsessive-compulsive behavior. People with ADHD are also more likely than the general population to have a family member with ADHD or one of the related conditions.

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