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Attention-deficit hyperactivity disorder
Attention-deficit hyperactivity disorder (ADHD) is one of the most commonly diagnosed mental disorders among children, although it also occurs in adults. It should be distinguished from non-organic conditions that mimic it, such as caffeinism.
The brain on the left belongs to a person who does not have ADHD, the brain on the right belongs to a person who does have ADHD. The official definitions of ADHD according to the US Surgeon General and ICD-9-CM (International Classification of Disease Revised Edition 2005) is a neurological deficit classified as "metabolic encephalopathy" affecting the release and homeostasis of neurological chemicals and the functioning of the limbic system.
The official definition of ADHD found in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders-IV (Text Revision) (DSM-IV-TR), defines three subtypes of ADHD:
* Predominantly Inattentive,
* Predominantly Hyperactive-Impulsive, and
* Combined Type.
Although most diagnoses of ADHD are made for children, the DSM definitions of ADHD do not confine the disorder solely to childhood and in fact many adults are also diagnosed. Current theory holds that approximately 30% of children diagnosed retain the disorder as adults. Although the disorder may not have been diagnosed in an individual during childhood, it is also currently thought that all adults with Adult attention-deficit disorder (AADD) had it in childhood. Hyperactivity and other symptoms may be less noticeable in adults with ADD/ADHD who have learned better coping skills and other forms of adaptive behavior than they had as children. Particularly in adults, studies have shown a high correlation between ADHD and creativity. Many painters and performing artists seem to show significant evidence of ADHD, particularly those drawn to improvisational humor and stand up comedy (see Robin Williams, the poster child for adult ADHD).
Terminology
There is not yet a naming consensus. Below are listed several terms that have been used, past and present. One challenge in taxonomy is that some patterns of behavior are labeled by experts symptoms or sub-types of ADHD, while other experts label those same patterns as their own disorders, independent of ADHD. For the purposes of this article, the "Terminology" section will be used only to name ADHD and its near equivalents, while the names for its manifestations and subtypes will be listed in 'Symptoms', below.
* Attention-deficit hyperactivity disorder (ADHD): In 1987, ADD was in effect renamed to ADHD in the DSM-III-R. In it, ADHD was broken down into three subtypes (see 'symptoms' for more details):
o predominantly inattentive ADHD
o predominantly hyperactive-impulsive ADHD
o combined type ADHD
* Attention deficit disorder (ADD): This term was first introduced in DSM-III, the 1980 edition. Is considered by some to be obsolete, and by others to be a synonym for the predominantly inattentive type of ADHD.
* Attention-deficit syndrome (ADS): Equivalent to ADHD, but used to avoid the connotations of "disorder".
* Hyperkinetic syndrome (HKS): Equivalent to ADHD, but largely obsolete in the United States, still used in some places world wide.
* Minimal cerebral dysfunction (MCD): Equivalent to ADHD, but largely obsolete in the United States, though still commonly used internationally.
* Minimal brain dysfunction or Minimal brain damage (MBD): Similar to ADHD, now obsolete.
Cause
The exact cause(s) of ADHD are not conclusively known. Scientific evidence suggests most strongly that, in many cases, the disorder is genetically transmitted and is caused by an imbalance or deficiency in certain chemicals that regulate the efficiency with which the brain controls behavior.
A 1990 study at the National Institute of Mental Health correlated ADHD with a series of metabolic abnormalities in the brain, providing further evidence that ADHD is a neurological disorder. While heredity is often indicated, problems in prenatal development, birth complications, or later neurological damage may contribute to ADHD.
Causes under investigation include, but are not limited to:
* Brain differences: Brain scan technology has revealed differences in the size, symmetry, metabolism, and chemistry of the brain in those who have ADHD; however, it should be noted that there is yet no clear determination of the source of these differences.
* Genetic factors: It has been demonstrated that children who have at least one parent diagnosed with ADHD are more likely to be diagnosed as having ADHD themselves. Current research is examining which genes may be involved in ADHD. This investigative path also suggests an associated hypothesis that environmental factors, handed down from generation to generation, may trigger the symptoms associated with ADHD. There also exists a possiblity that a family with one diagnosed member may have a heightened awareness of the disorder, along with a willingness to seek formal diagnosis, which would make detection and diagnosis more likely, thus skewing the data on heritability.
* Brain development in utero and during the first year of life, possibly related to drug use during pregnancy or environmental toxins.
It has also been suggested that ADHD may result from a poor diet and other external factors rather than from any physiological source. Studies of changes in diets of children provide some anecdotal and scientific evidence for this, but current majority opinion seems to be that the available evidence is insufficient to either prove or disprove this.
Research is ongoing in many studies.
Controversy
While ADD/ADHD is a known psychiatric condition, there are various theories about the cause and some controversy over the number of persons diagnosed and the cost of medications. Some denial in families may also relate to the negative perception of the condition as a hereditary brain disorder.
Skepticism towards ADHD as a diagnosis
Critics have complained that the ADHD diagnostic criteria are sufficiently general or vague to allow virtually any child with persistent unwanted behaviors to be classified as having ADHD of one type or another.
A growing number of critics have wondered why the number of children diagnosed with ADHD in the U.S. and UK has grown so dramatically over a short period of time.
It has often been suggested that the causes of the apparent ADHD epidemic lie in cultural patterns that variously encourage or sanction the use of drugs as a simple and expeditious cure for complex problems that may stem primarily from social and environmental triggers rather than any innate disorder. Some critics assert that many children are diagnosed with ADHD and put on drugs as a substitute for parental attention, whereas many parents of ADHD children assert that the associated demand for attention goes beyond what can be humanly provided, causing massive disruption to other individuals and relationships, as well as to environments with dysfunctionally structured relationships such as are manifest in many classrooms. This criticism also includes the use of prescription drugs as a substitute for parental duties such as communication and supervision.
Another source of skepticism towards making the diagnosis of "ADHD or not ADHD" may arise from the rising diagnosis of subclinical forms of ADHD. So called 'Shadow-syndromes' or 'sub-syndromes' stand for weaker forms of ADHD and are described in various degrees by John J. Ratey and Catherine Johnson on their book Shadow Syndromes: The Mild Forms of Major Mental Disorders That Sabotage Us.
Hunter-versus-farmer theory
A broad theory, not necessarily in conflict with the current medical research findings, is the hunter vs. farmer theory, first presented by Thom Hartmann, which holds that in some ways, some ADD attributes in some humans may be a form of adaptive behavior developed over a long period to match the environment. In easier terms, the change was refinement of skills to suit changing needs. Under the theory, as civilized society evolved, the attributes of a hunter gave way to those of a farmer for most people as the survival skills needed changed.
Hartmann takes an approach from biological evolution to argue that ADHD is not a disorder, but an expression of biodiversity. In his book ADD - Attention Deficit Disorder (1997), Hartmann developed the idea that people having ADHD symptoms may have simply inherited a collection of genes that were selected for the time when hunting was particularly important. From an evolutionary point of view, it is quite acceptable that humans—like other animals—differ in their biology and pass on their traits from generation to generation. This idea is the basis of another of his works, The Edison Gene: ADHD and the Gift of the Hunter Child (2003).
Hence the idea that thinking in terms of attentional 'differences' rather than attentional 'disorders' may be helpful, by helping focus energy towards the individual's strengths and uniqueness.
ADD/ADHD a hoax?
There are some claims that ADD/ADHD is simply a hoax. Many of these charges are that there has been a conspiracy between medical and counseling professionals and the pharmaceutical companies, or that the former has been misled by the latter, which have profited greatly from the sale of medication such as Ritalin and Adderall, and have advertised their products extensively. Since medications became available, there has been an increased number of persons diagnosed. This might be explained by increased awareness or easy solution for doctors.
However, the results achieved in clinical tests with such medication and anecdotal evidence of parents, teachers, and both child and adult sufferers has proved there is both a condition and successful treatment options for most people who meet the criteria for a diagnosis.
A further problem is that ADD and ADHD are syndromes, associations of symptoms. There is no well established cause for the condition. This means that it may actually be a blanket term covering a multitude of conditions with a variety of causes.
Confusion may also arise from the fact ADD/ADHD symptoms vary with each individual, and some mimic those of other causes. A known fact is that, as the body (and brain) matures and grows, the symptoms and adaptability of the individual also change. Many children diagnosed with ADD/ADHD seem to outgrow it as they mature. Clearly, other individuals experience the symptoms their entire lives.
Symptoms
* In children the disorder is characterized by inattentiveness to external direction, impulsive behavior and restlessness. However, children with the inattentive type are actually often sluggish and hypo-active.
* In adults the problem is often an inability to structure their lives and plan simple daily tasks. Thus, inattentiveness and restlessness often become secondary problems.
A diagnosis of ADHD is made based on a checklist of symptoms that can be found in DSM-IV-TR.
The CDC emphasizes that a diagnosis of ADHD should only be made by trained health care providers. This is important as many of the criteria can be readily misinterpreted and the prescribed drugs can be very dangerous.
Incidence
ADHD is considered by some to be a problem all over the industrialized world, although in no other country are children diagnosed with this disorder as often as in the United States.
According to the 2000 edition of DSM-IV-TR, ADHD affects three to seven percent of all children in the U.S. According to 2002 data from the CDC's annual National Health Interview Survey, released in 2004, nearly 4 million children younger than 18 in the United States had been diagnosed with attention deficit hyperactivity disorder (ADHD). The 2002 data indicated that twice as many boys were diagnosed with ADHD as girls (10% vs. 4%). Some experts theorize that ADHD is under-diagnosed in girls, since their symptoms tend to be less dramatic than those in boys and thus draw less attention from parents and teachers.
Psychological testing for ADHD
Psychological testing for ADHD symptoms generally consists of obtaining multiple types of assessments. These usually include a clinical interview reviewing the DSM-IV criteria for ADHD diagnosis. The interview also needs to rule out as much as possible other types of syndromes which can cause attention problems, such as depression, anxiety, allergies and psychosis. Rating scales can be administered which provide measurement of the person's own view of their symptoms, as well as the views of parents, teachers, and significant others.
Finally, computerized tests of attention can be helpful in providing a further independent assessment. These different assessments may not be consistent, but do provide a view of the person's difficulties. Subjectivity of the analysis can be compounded by the fact that physicians generally need not order psychological testing in order to make the diagnosis of ADHD, but many doctors use this kind of assessment to avoid over-diagnosis and treatment. The process of obtaining referrals for such assessments is being promoted vigorously by the President's New Freedom Commission on Mental Health.
Other forms of testing
Neurometrics, PET scans, or SPECT scans have been used for a more objective diagnosis. However, these are not usually suitable for very young children.
Treatment
There are many options available to treat people diagnosed with ADHD. These options include a variety of medications, behavior-changing therapies, and educational interventions.
Mainstream treatments The first-line medication used to treat ADHD are mostly stimulants, which work by stimulating the areas of the brain responsible for focus, attention, and impulse control. These include:
* Caffeine -- though not an official mainstream treatment, the ubiquitous use of caffeine means that it probably one of the most frequently used, unofficial treatments for ADHD. Caffeine is found in coffee, tea and cola soft drinks. Many students and adults will self-medicate with caffeine. Signs that one is self-medicating would be the observation that one's focus improves with the stimulant, and that one cannot function as well without it. Users often report that drinking caffeine in the evening does not impair their sleep, and that in fact, it may help soothe and relax them, thus helping them sleep better. Drinking only 1-2 cups daily is probably not self-medication, but someone who needs over 5 cups daily throughout the day in order to stay awake and focus may possibly be self-medicating.
* Nicotine -- found in cigarettes, many students and adults will self-medicate by needing to smoke several times daily.
* Methylphenidate -- Available in:
o Regular formulation, sold as Ritalin, Metadate, Methylin. Duration: 4-6 hours per dose. Usually taken morning, lunchtime, and in some cases, afternoon.
o Long acting formulation, sold as Ritalin SR, Metadate ER. Duration: 8 hours per dose. Usually taken twice daily.
o All-day formulation, sold as Ritalin LA, Metadate CD, Concerta. Duration: 10-12 hours per dose. Usually taken once a day.
* Amphetamines --
o Dextroamphetamine -- Available in:
+ Regular formulation, sold as Dexedrine. Duration: 4-6 hours per dose. Usually taken 2-3 times daily.
+ Long-acting formulation, sold as Dexedrine Spansules. Duration: 8-12 hours per dose. Taken once a day.
o Adderall, a trade name for a mixture of dextroamphetamine and laevoamphetamine salts. -- Available in:
+ Regular formulation, Adderall. Duration: 4-6 hours a dose.
+ Long-acting formulation, Adderall XR. Duration: 12 hours. Taken once a day.
o Methamphetamine -- Available in:
+ Regular formulation, sold as Desoxyn by Ovation Pharmacutical Company. Usually taken twice daily.
* Atomoxetine. A Selective Norepinephrine Reuptake Inhibitor (SNRI) introduced in 2002, it is the newest class of drug used to treat ADHD, and the first non-stimulant medication to be used as a first-line treatment for ADHD. Available in:
o Once daily formulation, sold by Eli Lilly and Company as Strattera. Duration: 24 hours per dose. Taken once a day.
Second-line medications include:
* benzphetamine -- a less powerful stimulant. Research on the effectiveness of this drug is not yet complete.
* Provigil/Alertec/modafinil -- Research on this drug is not yet complete.
* Cylert/Pemoline --a stimulant used with great success until the late 1980s when it was discovered that this medication could cause liver damage. Although some physicians do continue to prescribe Cylert, it can no longer be considered a first-line medicine. In March 2005 the makers of Cylert announced that it would discontinue the medication's production.
Because most of the medications used to treat ADHD are Schedule II under the U.S. DEA schedule system, and are considered powerful stimulants with a potential for diversion and abuse, there is controversy surrounding prescribing these drugs for children and adolescents. However, research studying ADHD sufferers who either receive treatment with stimulants or go untreated has indicated that those treated with stimulants are in fact much less likely to abuse any substance than ADHD sufferers who are not treated with stimulants.
Alternative treatments
There are many alternative treatments for ADHD, and all of them are as heavily disputed as the mainstream. This section attempts to deal with the most prominent of the alternative treatments.
Dr Ben F. Feingold, once a Professor of Allergy in San Francisco, claimed that hyperactivity was increasing in proportion to the level of food additives and proposed a specific diet believing that it would help 50% of hyperactive children.
The Feingold diet excluded cola drinks, chocolate, preservatives and flavor additives, as well as salicylates that occur naturally in fruit such as tomatoes, strawberries, pineapples and oranges. However pineapple juice was suggested as a "safe" drink.
The effectiveness of the Feingold diet has been heavily disputed. Most studies have shown that only 5% of children diagnosed with ADHD benefited from the diet (but this was obviously an important finding for that 5%). Other studies have shown a figure of 60%.
In the 1980s the vitamin B6 promoted as a helpful remedy for children with learning difficulties including inattentiveness. After that, zinc was promoted for ADD and autism. Multivitamins later became the claimed solution. Thus far, no reputable research has appeared to support any of these claims, except in cases of malnutrition.
There has been a lot of interesting work done with neurofeedback and ADHD. Children are taught, using video game-like technology, how to control their brain waves. This has a very high success rate, but is not widely used, or covered by insurance. Many professionals consider the treatment promising, but state that there is not yet sufficient evidence that it works after the immediate treatment is complete.
Possible causes
ADHD is broadly defined and pervasive, and the symptoms attributed to ADHD likely have a variety of different causes. The initial triggers could include genetic vulnerabilities, viral or bacterial infections, brain injury, or nutritional deficits. There has been a surge in alternative approaches to ADHD, but these have been vigorously disputed.
Neuro-chemical imbalance
There is increasing evidence that variants in the gene for the dopamine transporter are related to the development of ADHD (Roman et al., 2004, Am J Pharmacogenomics 4:83-92). This evidenceis consonant with the theory of inefficacy of dopamine in people with ADD/ADHD, as according to other recent studies, people with ADHD usually have an abnormally high amount of dopamine transporter, which clears dopamine from between neurons before the full effect is gained from the dopamine. The stimulant medications used to treat the disorder are all capable of either inhibiting the action of dopamine transporter (as methylphenidate does) or promoting the release of dopamine itself (as the amphetamine-class medications do). Therefore, it is theorized that stimulant medication allows the brain to enhance the effect of dopamine more efficiently by blocking the dopamine transporters or increasing the release of dopamine. Currently this theory is the most widely accepted model of ADD/ADHD etiology in the scientific and medical community.
New studies consider the possibility that norepinephrine also plays a role. (see Krause, Dresel, Krause in Psycho 26/2000 p.199ff).
Smoking during pregnancy
The finding of another possible cause stemmed from the observation that children of women who smoked during pregnancy are more likely to be diagnosed with ADHD (Kotimaa et al., 2003, J Am Acad Child Adol Psychiatry 42, 826-833). Given that nicotine is known to cause hypoxia (too little oxygen) in the uterus, and that hypoxia causes brain damage, smoking during pregnancy could be an important contributing factor leading to ADHD. It may even help explain in part the increase in ADHD diagnoses, as the number of women smokers has increased. However, there are not nearly enough women smoking during pregnancy to account for all the ADHD diagnoses.
Deficiencies in nutrition
It has been established conclusively that a small percentage of children are sensitive to dyes and other food additives, sugar, caffeine, etc. (Jacobson and Schardt, 1999, Diet, ADHD & Behavior, Center for Science in the Public Interest, Washington, DC).
Nutritional data has been well summarized in a review article (Burgess et al., 2000, Am J Clin Nutr 71:327-330). Children with ADHD have lower levels of key fatty acids. In fact, one study found that the lower the levels, the worse the symptoms. The possibility that fatty acid deficiency is a trigger for ADHD is especially plausible as nutrition scientists have recently demonstrated that the American diet is extremely deficient in omega-3 fatty acids. At the same time, ADHD diagnoses are rapidly increasing. More support for this idea comes from findings that breast-fed children have much lower levels of ADHD, and that until quite recently, infant formula contained NO omega-3 fatty acids. These findings are only correlational, and do not prove a conclusive connection.
However, creating a deficiency of omega-3 fatty acids in pregnant rats produces pups that are hyperactive and that have altered brain levels of dopamine in the same brain regions as seen in humans and other rat models of hyperactivity.
Sleep apnea
There is also new evidence that brief pauses in breathing (apnea) during infancy may be a cause of ADHD. Dr. Glenda Keating of Emory University presented data at the Society for Neuroscience annual meeting in October 2004, showing that repetitive drops in blood oxygen levels in newborn rats similar to that caused by apnea in some human infants is followed by a long-lasting reduction in dopamine levels, associated with ADHD. Apnea occurs in up to 85% of prematurely born human infants.
Head injuries
It has been known for some decades that head injuries can cause a person to experience and display ADHD-like symptoms.
The information above is not intended
for and should not be used as a substitute for the diagnosis and/or treatment
by a licensed, qualified, health-care professional. This article is licensed
under the GNU Free Documentation
License. It incorporates material originating from the Wikipedia article
"Attention-deficit
hyperactivity disorder".
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