Attention-deficit hyperactivity disorder

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Attention-deficit/hyperactivity disorder (USA)
Classification and external resources
ICD-10	F90.
ICD-9	314.00, 314.01
OMIM	143465
DiseasesDB	6158
MedlinePlus	001551
eMedicine	med/3103  ped/177
MeSH	D001289

Attention-deficit/hyperactivity disorder (ADHD or AD/HD) is a neurobehavioral^[1] developmental disorder.^[2] ADHD is defined as a “persistent pattern of inattention or hyperactivity—impulsivity that is more frequently displayed and more severe than is typically observed in individuals at a comparable level of development.”^[3] It is the most commonly diagnosed psychiatric disorder in children. It affects about 3 to 5% of children globally with symptoms starting before seven years of age.^[4][5] ADHD is generally a chronic^[6] disorder with 30 to 50% of those individuals diagnosed in childhood continuing to have symptoms into adulthood.^[7][8] As they mature, adolescents and adults with ADHD are likely to develop coping mechanisms to compensate for their impairment.^[9]

Though previously regarded as a childhood diagnosis, ADHD can continue throughout adulthood.^[10] Four percent of American adults are estimated to live with ADHD. ^[11]

ADHD is diagnosed twice as frequently in boys as in girls,^[12] though studies suggest this discrepancy may be due to subjective bias.^[13]

ADHD management usually involves some combination of medications, behavior modifications, lifestyle changes, or counseling.

In the first decade of the 2000s, ADHD diagnoses have increased dramatically in the United States, prompting some scholars from various fields to question the scientific validity of this relatively recent childhood disorder.^[14] ADHD and its diagnosis and treatment have been considered controversial since the 1970s.^[15] The controversies have involved clinicians, teachers, policymakers, parents and the media, with opinions regarding ADHD that range from not believing it exists at all to believing there are genetic and physiological bases for the condition and also include disagreement about the use of stimulant medications in treatment.^[16][17][18] Most healthcare providers accept that ADHD is a genuine disorder; debate in the scientific community centers mainly around how it is diagnosed and treated.^[19][20]

[edit] Classification

ADHD may be seen as an extreme of one or more continuous traits found throughout the population.^[21] ADHD is a developmental disorder in which certain traits such as impulse control lag in development when compared to the general population.^[22] Using magnetic resonance imaging of the prefrontal cortex, this developmental lag has been estimated to range from 3 to 5 years.^[23] These delays are considered to cause impairment. ADHD has also been classified as a behavior disorder.^[24] A diagnosis of ADHD does not, however, imply a neurological disease.^[21]

ADHD is classified as a disruptive behavior disorder along with oppositional defiant disorder, conduct disorder and antisocial disorder.^[25]

[edit] Childhood ADHD

Attention Deficit Hyperactivity Disorder or ADHD is a common childhood illness that can be treated. It is a health condition involving biologically active substances in the brain. Studies show that ADHD may affect certain areas of the brain that allow us to solve problems, plan ahead, understand others’ actions, and control our impulses.^[26]

The American Academy of Child Adolescent Psychiatry (AACAP) considers it necessary that the following be present before attaching the label of ADHD to a child:

• The behaviors must appear before age 7.
• They must continue for at least six months.
• The symptoms must also create a real handicap in at least two of the following areas of the child’s life:
  • in the classroom
  • on the playground
  • at home
  • in the community, or
  • in social settings^[26]

If a child seems too active on the playground but not elsewhere, the problem might not be ADHD. It might also not be ADHD if the behaviors occur in the classroom but nowhere else. A child who shows some symptoms would not be diagnosed with ADHD if his or her schoolwork or friendships are not impaired by the behaviors.^[26]

Even if a child’s behavior seems like ADHD, it might not actually be ADHD. Many other conditions and situations can trigger behavior that resembles ADHD. For example, a child might show ADHD symptoms when experiencing:

• A death or divorce in the family, a parent’s job loss, or other sudden change
• Undetected seizures
• An ear infection that causes temporary hearing problems
• Problems with schoolwork caused by a learning disability
• Anxiety or depression^[26]
• Insufficient or poor quality sleep

[edit] Adult ADHD

It has been estimated that about eight million adults have ADHD in the United States.^[27] Untreated adults with ADHD often have chaotic lifestyles, may appear to be disorganized and may rely on non-prescribed drugs and alcohol to get by.^[28] They often have such associated psychiatric comorbidities as depression, anxiety disorder, bipolar disorder, substance abuse, or a learning disability.^[28] A diagnosis of ADHD may offer adults insight into their behaviors and allow patients to become more aware and seek help with coping and treatment strategies.^[27]

There is controversy amongst experts on whether ADHD persists into adulthood. Recognized as occurring in adults in 1978, it is currently not addressed separately from ADHD in childhood. Obstacles that clinicians face when assessing adults who may have ADHD include developmentally inappropriate diagnostic criteria, age-related changes, comorbidities and the possibility that high intelligence or situational factors can mask ADHD symptoms.^[29]

[edit] Symptoms

The most common symptoms^[30][31] of ADHD are:

• Impulsiveness: acting before thinking of consequences, jumping from one activity to another, disorganization, tendency to interrupt other peoples' conversations.^[30]
• Hyperactivity: restlessness, often characterized by an inability to sit still, fidgeting, squirminess, climbing on things, restless sleep.^[30]
• Inattention: easily distracted, day-dreaming, not finishing work, difficulty listening,^[30] and motor clumsiness.^[32]

The DSM-IV categorizes the symptoms of ADHD into three clusters, referred to as subtypes: (1) Inattentive; (2) hyperactive/impulsive; and (3) combined.^[33] Most people exhibit some of these behaviors, but not to the degree where such behaviors significantly interfere with a person's work, relationships, or studies. The core impairments are consistent even in different cultural contexts.^[34]

ADHD may accompany other disorders such as anxiety or depression. Such combinations can greatly complicate diagnosis and treatment. Academic studies and research in private practice suggest that depression in ADHD appears to be increasingly prevalent in children as they get older, with a higher rate of increase in girls than in boys, and to vary in prevalence with the subtype of ADHD. Where a mood disorder complicates ADHD it would be prudent to treat the mood disorder first, but parents of children who have ADHD often wish to have the ADHD treated first, because the response to treatment is quicker.^[35]

Hyperactivity is common among children with ADHD but tends to disappear during adulthood. However, over half of children with ADHD continue to have some symptoms of inattention throughout their lives.^{[citation needed]}

A 2009 study found that children with ADHD move around a lot because it helps them stay alert enough to complete challenging tasks. The researcher advises that when they are doing homework, let them fidget, stand or chew gum since it may help them cope. Unless their behavior is destructive, severely limiting their activity could be counterproductive.^[36]

Inattention and "hyperactive" behavior are not the only problems in children with ADHD. ADHD exists alone in only about 1/3 of the children diagnosed with it. Many co-existing conditions require other courses of treatment and should be diagnosed separately instead of being grouped in the ADHD diagnosis. Some of the associated conditions are:

• Oppositional defiant disorder (35%) and conduct disorder (26%) which both are characterized by anti-social behaviors such as stubbornness, aggression, frequent temper tantrums, deceitfulness, lying, or stealing.^[31]
• Primary disorder of vigilance, which is characterized by poor attention and concentration, as well as difficulties staying awake. These children tend to fidget, yawn and stretch and appear to be hyperactive in order to remain alert and active.^[31]
• Mood disorders. Boys diagnosed with the combined subtype have been shown more likely to suffer from a mood disorder.^[37]
• Bipolar disorder. As many as 25% of children with ADHD have bipolar disorder. Children with this combination may demonstrate more aggression and behavioral problems than those with ADHD alone.^[31]
• Anxiety disorder, which has been found to be more common in girls diagnosed with the inattentive subtype of ADHD.^[38]
• Obsessive-compulsive disorder. OCD is believed to share a genetic component with ADHD and shares many of its characteristics.^[31]

[edit] Causes

A specific cause of ADHD is not known.^[39] There are, however, a number of factors that may contribute to ADHD including genetics, diet and social and physical environments.

[edit] Genetic factors

Twin studies indicate that the disorder is highly heritable and that genetics are a factor in about 75% of ADHD cases.^[21] Hyperactivity also seems to be primarily a genetic condition; however, other causes do have an effect.^[40]

Researchers believe that a large majority of ADHD cases arise from a combination of various genes, many of which affect dopamine transporters. Candidate genes include dopamine transporter, dopamine receptor D4, dopamine beta-hydroxylase, monoamine oxidase A, catecholamine-methyl transferase, serotonin transporter promoter (SLC6A4), 5-hydroxytryptamine 2A receptor (5-HT2A), 5-hydroxytryptamine 1B receptor (5-HT1B),^[41] the 10-repeat allele of the DAT1 gene,^[42] the 7-repeat allele of the DRD4 gene,^[42] and the dopamine beta hydroxylase gene (DBH TaqI).^[43]

The broad selection of targets indicates that ADHD does not follow the traditional model of a "genetic disease" and should therefore be viewed as a complex interaction among genetic and environmental factors. Even though all these genes might play a role, to date no single gene has been shown to make a major contribution to ADHD.^[44]

[edit] Environmental factors

Twin studies to date have also suggested that approximately 9% to 20% of the variance in hyperactive-impulsive-inattentive behavior or ADHD symptoms can be attributed to nonshared environmental (nongenetic) factors.^[45][46]

Environmental factors implicated include alcohol and tobacco smoke exposure during pregnancy and environmental exposure to lead in very early life.^[47] The relation of smoking to ADHD could be due to nicotine causing hypoxia (lack of oxygen) to the fetus in utero.^[48] It could also be that women with ADHD are more likely to smoke^[49] and therefore, due to the strong genetic component of ADHD, are more likely to have children with ADHD.^[50] Complications during pregnancy and birth—including premature birth—might also play a role.^[51]

[edit] Diet

For some children, diet is suspected of playing a role in the multiple behavioral and cognitive symptoms of attention deficit hyperactivity disorder (ADHD). Concerns have focused on food additives, blood sugar regulation, food allergies and intolerances, and vitamin, mineral and fatty acid deficiencies.

[edit] Additives

For more than 30 years, questions have been raised about whether the synthetic dyes, flavors, and preservatives found in many commercially prepared and “junk” foods might contribute to hyperactivity or other symptoms of ADHD. Traditional research found limited support for diets like the Feingold diet, which eliminates certain processed foods and food additives as well as certain fruits and vegetables.

In September 2007, research financed by Britain’s Food Standards Agency and published online by the British medical journal The Lancet presented evidence that a mix of additives commonly found in children’s foods increases the mean level of hyperactivity.^[52] The team of researchers concluded that “the finding lends strong support for the case that food additives exacerbate hyperactive behaviors (inattention, impulsivity and overactivity) at least into middle childhood.” That study examined the effect of artificial colors and a sodium benzoate preservative, and found both to be problematic for some children. Further studies are needed to find out whether there are other additives that could have a similar effect, and it is unclear whether some disturbances can also occur in mood and concentration in some adults. In the February 2008 issue of its publication, AAP Grand Rounds, the American Academy of Pediatrics concluded that a low-additive diet is a valid intervention for children with ADHD:

“Although quite complicated, this was a carefully conducted study in which the investigators went to great lengths to eliminate bias and to rigorously measure outcomes. The results are hard to follow and somewhat inconsistent. For many of the assessments there were small but statistically significant differences of measured behaviors in children who consumed the food additives compared with those who did not. In each case increased hyperactive behaviors were associated with consuming the additives. For those comparisons in which no statistically significant differences were found, there was a trend for more hyperactive behaviors associated with the food additive drink in virtually every assessment. Thus, the overall findings of the study are clear and require that even we skeptics, who have long doubted parental claims of the effects of various foods on the behavior of their children, admit we might have been wrong.”

Several other recent studies have renewed interest in whether certain foods and additives might affect particular symptoms in a subset of children with ADHD.^[53]

As of mid-2009, the consensus on a sensible approach to nutrition for children with ADHD is the same recommended for all children: eat a diet that emphasizes fruits and vegetables, whole grains, healthful unsaturated fats, and good sources of protein; go easy on unhealthy saturated and trans fats, rapidly digested carbohydrates, and fast food; and balance healthy eating with plenty of physical activity. (Emphasis added) ^[53]

As yet there is no consensus about how such additives might contribute to ADHD symptoms in children. In a recent well-designed study in Britain, the investigators found a mild but significant increase in hyperactivity in both age^{[clarification needed]} groups of children—across the board, regardless of baseline hyperactivity levels—during the weeks when they consumed drinks containing artificial colors. This study concluded that the additives might explain about 10% of the behavioral difference between a child with ADHD and one without the disorder.^[53]

An earlier meta-analysis conducted at Columbia University and Harvard University suggests that removing these agents from the diets of children with ADHD would be about one-third to one-half as effective as treatment with methylphenidate (Ritalin).^[53]

Authors of both of these studies cautioned that only a minority of children are particularly vulnerable to the effects of artificial additives. They also pointed out that determining which children are susceptible is difficult, though not impossible.^[53]

The European Food Safety Authority (EFSA) reviewed the literature on the association between food additives and hyperactivity and concluded that there is only limited evidence of an association between the intake of additives and activity and attention and then only in some children studied. They further indicated that the effects reported in the study were not consistent for the two age groups and for the two food additive mixtures used in the study.^[54] Others have suggested a trial of removing additives from the diet for children with ADHD as it is harmless and might be helpful.^[55]

[edit] Sugar regulation

A number of studies have found that sucrose (sugar) has no effect on behavior and in particular it does not exacerbate the symptoms of children diagnosed with ADHD.^[56][57][58]

[edit] Omega-3 fatty acids

Essential fatty acids fuel basic cell functioning, improve overall immunity, and enhance heart health. By definition, the body cannot make essential fatty acids, so these nutrients must be consumed in the diet. Some evidence suggests that children with ADHD may have low levels of essential fatty acids. More studies are continuing. In the meantime, the American Psychiatric Association’s Omega-3 Fatty Acids Subcommittee encourages children with ADHD to consume levels of omega-3 fatty acids recommended as part of a healthy diet. That means a child should consume up to 12 ounces (two average meals) a week of a variety of fish and shellfish that are low in mercury, such as shrimp, canned light tuna, salmon, and pollack, along with daily plant sources of unsaturated fats.^[53]

[edit] Vitamin and mineral supplements

Although vitamin or mineral supplements (micronutrients) may help children diagnosed with particular deficiencies, there is no evidence that they are helpful for all children with ADHD. Furthermore, megadoses of vitamins, which can be toxic, must be avoided.^[53]

[edit] Social factors

There is no compelling evidence that social factors alone can cause ADHD.^[22] However, many researchers believe that relationships with caregivers have a profound effect on attentional and self-regulatory abilities. A study of foster children found that a high number of them had symptoms closely resembling ADHD,^[59] while other researchers have found behavior typical of ADHD in children who have suffered violence and emotional abuse.^[21][60] Furthermore, Complex Post Traumatic Stress Disorder can result in attention problems that can look like ADHD.^[61] ADHD is also considered a contributing factor to Sensory Integration Disorders.^[62]

[edit] Alternative theories

[edit] Hunter vs. farmer theory of ADHD

The hunter vs. farmer theory is a hypothesis proposed by author Thom Hartmann about the origins of ADHD. He believes that these conditions may be a result of adaptive behavior of the human species. His theory states that those with ADHD retain some of the older "hunter" characteristics associated with early pre-agricultural human society.^[63]

[edit] Neurodiversity

Proponents of this theory assert that atypical (neurodivergent) neurological development is a normal human difference that is to be tolerated and respected just like any other human difference. Social critics argue that while biological factors may play a large role in difficulties with sitting still in class and/or concentrating on schoolwork in some children, these children could have failed to integrate others' social expectations of their behavior for a variety of other reasons.^[64] Others have said that ADHD has a link with creativity.^[65] As genetic research into ADHD proceeds, it may become possible to integrate this information with the neurobiology in order to distinguish disability from varieties of normal or even exceptional functioning in people along the same spectrum of attention differences. ^[66]

[edit] Social construct theory of ADHD

Some social critics question whether or not ADHD is wholly or even predominantly a biological illness.^[67] Some of these critics, such as Thomas Szasz, maintain that ADHD was "invented and not discovered."^[68][69] They believe that no such disorder exists and that the behavior observed may be better explained by environmental causes or simply the personality of the person.^[70]

[edit] Low arousal theory

The low arousal theory explains that people with ADHD seek self-stimulation or excessive activity in order to ascend their state of abnormally low arousal.^[71][72] The theory states that those with ADHD cannot self-moderate and their attention can only be gained by means of environmental stimuli.^[71]

Without enough stimulation coming from the environment, an ADHD child will create it him or herself by walking around, fidgeting, talking, etc. This theory also explains why stimulant medications have high success rates and can induce a calming effect at therapeutic dosages among children with ADHD. It establishes a strong link with scientific data that ADHD is connected to abnormalities with the neurochemical dopamine and a powerful link with low-stimulation PET scan results in ADHD subjects.^[71]

[edit] Pathophysiology

The pathophysiology of ADHD is unclear and there are a number of competing theories.^[73] Neuroimaging studies in ADHD have not always given consistent results and as of 2008 are only used for research purposes.^[74]

In one study a delay in development of certain brain structures by an average of three years occurred in ADHD elementary school aged patients. The delay was most prominent in the frontal cortex and temporal lobe, which are believed to be responsible for the ability to control and focus thinking. In contrast, the motor cortex in the ADHD patients was seen to mature faster than normal, suggesting that both slower development of behavioral control and advanced motor development might be required for the fidgetiness that characterizes ADHD.^[75] It should be noted that stimulant medication itself can affect growth factors of the central nervous system.^[76]

The same laboratory had previously found involvement of the "7-repeat" variant of the dopamine D4 receptor gene, which accounts for about 30 percent of the genetic risk for ADHD, in unusual thinness of the cortex of the right side of the brain; however, in contrast to other variants of the gene found in ADHD patients, the region normalized in thickness during the teen years in these children, coinciding with clinical improvement.^[77]

Additionally, SPECT scans found people with ADHD to have reduced blood circulation (indicating low neural activity),^[78] and a significantly higher concentration of dopamine transporters in the striatum which is in charge of planning ahead.^[79][80] A study by the U.S. Department of Energy’s Brookhaven National Laboratory in collaboration with Mount Sinai School of Medicine in New York suggest that it is not the dopamine transporter levels that indicate ADHD, but the brain's ability to produce dopamine itself. The study was done by injecting 20 ADHD subjects and 25 control subjects with a radiotracer that attaches itself to dopamine transporters. The study found that it was not the transporter levels that indicated ADHD, but the dopamine itself. ADHD subjects showed lower levels of dopamine across the board. They speculated that since ADHD subjects had lower levels of dopamine to begin with, the number of transporters in the brain was not the telling factor. In support of this notion, plasma homovanillic acid, an index of dopamine levels, was found to be inversely related not only to childhood ADHD symptoms in adult psychiatric patients, but to "childhood learning problems" in healthy subjects as well.^[81]

Although there is evidence for dopamine abnormalities in ADHD, it is not clear whether abnormalities of the dopamine system are the molecular abnormality of ADHD or a secondary consequence of a problem elsewhere.^{[citation needed]} Researchers have described a form of ADHD in which the abnormality appears to be sensory overstimulation resulting from a disorder of ion channels in the peripheral nervous system.

A 1990 PET scan study by Alan J. Zametkin et al. found that global cerebral glucose metabolism was 8% lower in medication-naive adults who had been hyperactive since childhood.^[82] Further studies found that chronic stimulant treatment had little effect on global glucose metabolism,^[83] a study in girls failed to find a decreased global glucose metabolism,^[84] and in teenagers PET scans were unable to differentiate normal children from those with ADHD.^[85] The significance of the research by Zametkin has not been determined and neither his group nor any other has been able to replicate the 1990 results.^[86][87][88]

Critics, such as Jonathan Leo and David Cohen, who reject the characterization of ADHD as a disorder, contend that the controls for stimulant medication usage were inadequate in some lobar volumetric studies which makes it impossible to determine whether ADHD itself or psychotropic medication used to treat ADHD is responsible for decreased thickness observed^[89] in certain brain regions.^[90][91] They believe many neuroimaging studies are oversimplified in both popular and scientific discourse and given undue weight despite deficiencies in experimental methodology.^[90]

[edit] Diagnosis

No objective test exists to make a diagnosis of ADHD. It thus remains a clinical diagnosis.^[92]

In North America, the DSM-IV criteria are often the basis for a diagnosis, while European countries usually use the ICD-10.^[93]

Many of the symptoms of ADHD occur from time to time in everyone; in patients with ADHD, the frequency of these symptoms is greater and patients' lives are significantly impaired. Impairment must occur in multiple settings to be classified as ADHD. As with many other psychiatric and medical disorders, the formal diagnosis is made by a qualified professional in the field based on a set number of criteria. In the USA these criteria are laid down by the American Psychiatric Association in their Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), 4th edition. Based on the DSM-IV criteria listed below, three types of ADHD are classified:

1. ADHD, Combined Type: if both criteria 1A and 1B are met for the past 6 months
2. ADHD Predominantly Inattentive Type: if criterion 1A is met but criterion 1B is not met for the past six months
3. ADHD, Predominantly Hyperactive-Impulsive Type: if criterion 1B is met but criterion 1A is not met for the past six months.

The previously used term ADD expired with the most recent revision of the DSM. Consequently, ADHD is the current nomenclature used to describe the disorder as one distinct disorder which can manifest itself as being a primary deficit resulting in hyperactivity/impulsivity (ADHD, predominately hyperactive-impulsive type) or inattention (ADHD predominately inattentive type) or both (ADHD combined type).

[edit] DSM-IV criteria

I. Either A or B:^[33]

(A.) Six or more of the following symptoms of inattention have been present for at least 6 months to a point that is disruptive and inappropriate for developmental level:

• Inattentive:

1. Often does not give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
2. Often has trouble keeping attention on tasks or play activities.
3. Often does not seem to listen when spoken to directly.
4. Often does not follow instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions).
5. Often has trouble organizing activities.
6. Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long period of time (such as schoolwork or homework).
7. Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books, or tools).
8. Is often easily distracted.
9. Often forgetful in daily activities.

(B.) Six or more of the following symptoms of hyperactivity-impulsivity have been present for at least 6 months to an extent that is disruptive and inappropriate for developmental level:

• Hyperactivity:

1. Often fidgets with hands or feet or squirms in seat.
2. Often gets up from seat when remaining in seat is expected.
3. Often runs about or climbs when and where it is not appropriate (adolescents or adults may feel very restless).
4. Often has trouble playing or enjoying leisure activities quietly.
5. Is often "on the go" or often acts as if "driven by a motor".
6. Often talks excessively.

• Impulsiveness:

1. Often blurts out answers before questions have been finished.
2. Often has trouble waiting one's turn.
3. Often interrupts or intrudes on others (e.g., butts into conversations or games).

II. Some symptoms that cause impairment were present before age 7 years.

III. Some impairment from the symptoms is present in two or more settings (e.g. at school/work and at home).

IV. There must be clear evidence of significant impairment in social, school, or work functioning.

V. The symptoms do not happen only during the course of a Pervasive Developmental Disorder, Schizophrenia, or other Psychotic Disorder. The symptoms are not better accounted for by another mental disorder (e.g. Mood Disorder, Anxiety Disorder, Dissociative Disorder, or a Personality Disorder).

[edit] ICD-10

In the tenth edition of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) the symptoms of ADHD are given the name "Hyperkinetic disorders". When a conduct disorder (as defined by ICD-10^[94]) is present, the condition is referred to as "Hyperkinetic conduct disorder". Otherwise the disorder is classified as "Disturbance of Activity and Attention", "Other Hyperkinetic Disorders" or "Hyperkinetic Disorders, Unspecified". The latter is sometimes referred to as, "Hyperkinetic Syndrome".^[94]

[edit] Other diagnostic guidelines

The American Academy of Pediatrics Clinical Practice Guideline for children with ADHD emphasizes that a reliable diagnosis is dependent upon the fulfillment of three criteria:^[95]

• The use of explicit criteria for the diagnosis using the DSM-IV-TR.
• The importance of obtaining information about the child’s symptoms in more than one setting.
• The search for coexisting conditions that may make the diagnosis more difficult or complicate treatment planning.

All three criteria are determined using the patient's history given by the parents, teachers and/or the patient.

Adults often continue to be impaired by ADHD. Adults with ADHD are diagnosed under the same criteria, including the stipulation that their symptoms must have been present prior to the age of seven.^[96] Adults face some of their greatest challenges in the areas of self-control and self-motivation, as well as executive functioning, usually having more symptoms of inattention and fewer of hyperactivity or impulsiveness than children do.^[97]

[edit] Comorbid conditions

Common comorbid conditions include oppositional defiant disorder (ODD). About 20% to 25% of children with ADD meet criteria for a learning disorder.^[98] Learning disorders are more common when there are inattention symptoms.^[99]

Comorbid disorders or substance abuse can make the diagnosis and treatment of ADHD more difficult. Psychosocial therapy is useful in treating some comorbid conditions.^[100] ADHD is not, in boys, associated with increased substance misuse unless there is comorbid conduct disorder; but "research needs to examine the extent to which ADHD in adulthood increases the risk of substance use disorders."^[101]

Depression may also coincide with ADHD, increasingly prevalent among girls and older children.^[35]

Epilepsy is a commonly found comorbid disorder in ADHD diagnosed individuals. Some forms of epilepsy can also cause ADHD like behaviour which can be misdiagnosed as ADHD.^[102][103]

[edit] Differential diagnoses

To make the diagnosis of ADHD, a number of other possible medical and psychological conditions must be excluded.

Medical conditions

Medical conditions that must be excluded include: hypothyroidism, anemia, lead poisoning, chronic illness, hearing or vision impairment, substance abuse, medication side effects, sleep impairment and child abuse, among others.^[104]

Sleep conditions

Among other psychological and neurological issues, the relationship between ADHD and sleep is complex. In addition to clinical observations, there is substantial empirical evidence from a neuroanatomic standpoint to suggest that there is considerable overlap in the central nervous system centers that regulate sleep and those that regulate attention/arousal.^[105] Primary sleep disorders play a role in the clinical presentation of symptoms of inattention and behavioral dysregulation. There are multilevel and bidirectional relationships among sleep, neurobehavioral functioning and the clinical syndrome of ADHD.^[106]

Behavioral manifestations of sleepiness in children range from classic manifestations (yawning, rubbing eyes), to externalizing behaviors (impulsivity, hyperactivity, aggressiveness), to mood lability and inattentiveness.^[105][107]

From a clinical standpoint, mechanisms that account for the phenomenon of excessive daytime sleepiness include:

• Chronic sleep deprivation, that is insufficient sleep for physiologic sleep needs,
• Fragmented or disrupted sleep, caused by, for example, obstructive sleep apnea (OSA) or periodic limb movement disorder (PLMD),
• Primary clinical disorders of excessive daytime sleepiness, such as narcolepsy and
• Circadian rhythm disorders, such as delayed sleep phase syndrome (DSPS).

All of these are important causes of symptoms which may overlap with the cardinal symptoms of ADHD and children with ADHD should be regularly and systematically assessed for sleep problems.^[105][108]

[edit] Management

Methods of treatment often involve some combination of behavior modification, medication, life-style changes and counseling. Combined medical management and behavioral treatment is the most effective ADHD management strategy, followed by medication alone, and then behavioral treatment.^[109]

[edit] Pharmacological treatment

Management with medication has been shown to be the most cost-effective, followed by behavioral treatment and combined treatment.^[109] Stimulants are the most commonly prescribed medications for ADHD. The most common stimulant medications are methylphenidate (Ritalin, Metadate, Concerta), dextroamphetamine (Dexedrine), dextromethamphetamine (Desoxyn) and mixed amphetamine salts (Adderall)^[110] Lisdexamphetamine (Vyvanse).

One study found that children with ADHD actually need to move more to maintain the required level of alertness while performing tasks that challenge their working memory. Performing math problems mentally and remembering multi-step directions are examples of tasks that require working memory, which involves remembering and manipulating information for a short time. These findings may also explain why stimulant medications improve the behavior of most children with ADHD. Those medications improve the physiological arousal of children with ADHD, increasing their alertness.^[36] Previous studies have shown that stimulant medications temporarily improve working memory abilities.

Atomoxetine (Strattera) is currently the only non-stimulant drug approved for the treatment of ADHD. Other medications which may be prescribed off-label include certain antidepressants such as tricyclic antidepressants, SNRIs or MAOIs.^{[111][112][113][114]} A 2007 drug class review found that there are no good studies of comparative effectiveness between various drugs for ADHD and that there is a lack of quality evidence on their effects on overall academic performance and social behaviors.^[115] The long term effects of ADHD medications in preschool children are unknown and are not recommended for pre-school children.^[21][116]

Stimulants used to treat ADHD raise the extracellular concentrations of the neurotransmitters dopamine and norepinephrine which causes an increase in neurotransmission. The therapeutic benefits are due to noradrenergic effects at the locus coeruleus and the prefrontal cortex and dopaminergic effects at the nucleus accumbens. ^[117]

Although "under medical supervision, stimulant medications are considered safe",^[95][118] the use of stimulant medications for the treatment of ADHD has generated controversy because of undesirable side effects, uncertain long term effects^{[10][119][120][121][122]} and social and ethical issues regarding their use and dispensation. The FDA has added black-box warnings to some ADHD medications.^[123][124] The American Heart Association and the American Academy of Pediatrics feels that it is prudent to carefully assess children for heart conditions before treating them with stimulant medications.^[125]

[edit] Behavioral interventions

Psychological therapies use to treat ADHD include psychoeducational input, behavior therapy, cognitive behavioral therapy (CBT), interpersonal psychotherapy (IPT), family therapy, school-based interventions, social skills training and parent management training.^[21]

Parent training and education have been found to have short term benefits.^[126] Family therapy has shown to be of little use in the treatment of ADHD,^[127] though it may be worth noting that parents of children with ADHD are more likely to divorce than parents of children without ADHD, particularly when their children are younger than eight years old.^[128]

Several ADHD specific support groups exist as informational sources and to help families cope with challenges associated with dealing with ADHD.

[edit] Experimental treatments

Dietary supplements and specialized diets are sometimes used by people with ADHD with the intent to mitigate some or all of the symptoms. For example, Omega-3 supplementation may reduce ADHD symptoms for a subgroup of children and adolescents with ADHD "characterized by inattention and associated neurodevelopmental disorders."^[129] The effectiveness of these dietary supplements and specialized diets is debated because in many cases preliminary studies investigating their efficacy are small in scope or followup investigations have conflicting results. In the United States, no dietary supplement has been approved for the treatment for ADHD by the FDA.^[130]

EEG biofeedback also sometimes referred to as neurofeedback is effective in treating attention, impulsivity and hyperactivity. There are no known side effects from biofeedback therapy although research into biofeedback has been limited and further research has been recommended.^[131]

Aerobic fitness may improve cognitive functioning and neural organization related to executive control during pre-adolescent development, though more studies are needed in this area.^[132] One study suggests that athletic performance in boys with ADHD may increase peer acceptance when accompanied by fewer negative behaviors.^[133]

[edit] Prognosis

The proportion of children meeting the diagnostic criteria for ADHD dropped by about 50% over three years after the diagnosis. This occurred regardless of the treatments used and also occurs in untreated ADHD children.^{[104][121][134]} ADHD persists into adulthood in about 30-50% of cases.^[7] Those affected are likely to develop coping mechanisms as they mature, thus compensating for their previous ADHD.^[9]

Children diagnosed with ADHD have significant difficulties in adolescence, regardless of treatment.^[135] In the United States, 37% of those with ADHD do not get a high school diploma even though many of them will receive special education services.^[22] The combined outcomes of the expulsion and dropout rates indicate that almost half of all ADHD students never finish high school.^[136] Also in the US, less than 5% of individuals with ADHD get a college degree^[137] compared to 28% of the general population.^[138]

People with ADHD tend to work better in less structured environments with fewer rules^{[citation needed]}. Self-employment or jobs with greater autonomy are generally well suited for them. Hyperactive types are likely to change jobs often due to their constant need for new interests and stimulations to keep motivated.

[edit] Epidemiology

ADHD's global prevalence is estimated at 3-5% in people under the age of 19. There is, however, both geographical and local variability among studies. Geographically, children in North America appear to have a higher rate of ADHD than children in Africa and the Middle East,^[139] well published studies have found rates of ADHD as low as 2% and as high as 14% among school aged children.^[24] The rates of diagnosis and treatment of ADHD are also much higher on the East Coast of the USA than on the West Coast.^[140] The frequency of the diagnosis differs between male children (10%) and female children (4%) in the United States.^[141] This difference between genders may reflect either a difference in susceptibility or that females with ADHD are less likely to be diagnosed than males.^[142]

Rates of ADHD diagnosis and treatment have increased in both the UK and the USA since the 1970s. In the UK an estimated 0.5 per 1,000 children had ADHD in the 1970s, while 3 per 1,000 received ADHD medications in the late 1990s. In the USA in the 1970s 12 per 1,000 children had the diagnosis, while in the late 1990s 34 per 1,000 had the diagnosis and the numbers continue to increase.^[21]

In the UK in 2003 a prevalence of 3.6% is reported in male children and less than 1% is reported in female children.^[143]

[edit] History and culture

[edit] History

Hyperactivity has long been part of the human condition. Sir Alexander Crichton describes "mental restlessness" in his 1798 book.^[144][145] The terminology used to describe the symptoms of ADHD has gone through many changes over history including: "minimal brain damage", "minimal brain dysfunction", "learning/behavioral disabilities" and "hyperactivity". In the DSM-II (1968) it was the "Hyperkinetic Reaction of Childhood". In the DSM-III "ADD (Attention-Deficit Disorder) with or without hyperactivity" was introduced. In 1987 this was changed to ADHD in the DSM-III-R and subsequent editions.^[146] The use of stimulants to treat ADHD was first described in 1937.^[147]

[edit] Culture

Adaptive explanations of the high frequency of ADHD in contemporary settings propose that "the disorder represents otherwise normal behavioral strategies that become maladaptive in such evolutionarily novel environments as the formal school classroom." However, one study showed that inattention and hyperactivity appear to be at least as problematic at home as at school.^[148]

ADHD is considered differently based^{[clarification needed]} on how those who have an interest in the topic approach the subject. Depending on one's paradigm^[vague], the meanings of ADHD related subjects and terms vary within the everyday language of lay persons. One study identified five ways that lay persons borrow and interpret ADHD dialogue originating in professional literature and practice. The authors suggest that the language used in professional ADHD discourse may influence people's perceptions of the disorder. ^[149] There is disagreement about this observation.^[150]

The media has reported on many issues related to ADHD. In 2001 PBS's Frontline aired a one-hour program about the effects of the diagnosing and treating of ADHD in minors, entitled "Medicating Kids."^[151] The program included a selection of interviews with representatives of various points of view. In one segment, entitled Backlash, retired neurologist Fred Baughman and Peter Breggin who PBS described as "outspoken critics who insist [ADHD is] a fraud perpetrated by the psychiatric and pharmaceutical industries on families anxious to understand their children's behavior"^[152] were interviewed on the legitimacy of the disorder. Russell Barkley and Xavier Castellanos, then head of ADHD research at the National Institute of Mental Health (NIMH), defended the viability of the disorder. In Castellanos's interview he stated how little is scientifically understood.^[153] Lawrence Diller was interviewed on the business of ADHD along with a representative from Shire Plc.^{[citation needed]}

A number of notable individuals have given controversial opinions on ADHD. Scientologist Tom Cruise's interview with Matt Lauer was widely watched by the public. In this interview he spoke about postpartum depression and also referred to Ritalin and Adderall as being "street drugs" rather than as ADHD medication.^[154] In England Baroness Susan Greenfield, a leading neuroscientist,^[155] spoke out publicly about the need for a wide-ranging inquiry in the House of Lords into the dramatic increase in the diagnosis of ADHD in the UK and possible causes^[156] following a 2007 BBC Panorama programme which highlighted US research (The Multimodal Treatment Study of Children with ADHD by the University of Buffalo showing treatment results of 600) suggesting drugs are no better than therapy for ADHD in the long-term.^{[citation needed]}

As of 2009^[update], eight percent of all Major League Baseball players have been diagnosed with ADHD, making the disease epidemic among this population. The increase coincided with the League's 2006 ban on stimulants (q.v. Major League Baseball drug policy).^[157]

[edit] Controversies

This section may require copy-editing.

Attention-deficit hyperactivity disorder (ADHD) is a highly controversial psychiatric disorder.^[17][158] The high rates of ADHD diagnosis is very controversial with promotion of ADHD to the public as well as policies aimed at schools which force schools to identify children with ADHD being blamed for over diagnosis.^{[opinion needs balancing][159]} One source of controversy is that the pathophysiology of ADHD is currently unclear.^{[clarification needed][160]} The controversies have involved clinicians, teachers, policymakers, parents and the media, with opinions regarding ADHD ranging from those who do not believe it exists at all to those who believe that there are genetic and physiological bases for the condition.^[161] Most healthcare providers accept that ADHD is a genuine disorder with debate in the scientific community mainly around how it is diagnosed and treated.^[19][20]

Researchers from the McMaster University Evidence-based Practice Center identified five features of ADHD that contribute to its controversial nature: 1) it is a clinical diagnosis for which there are no laboratory or radiological confirmatory tests or specific physical features; 2) diagnostic criteria have changed frequently; 3) there is no curative treatment, so long-term therapies are required; 4) therapy often includes stimulant drugs that are thought to have abuse potential; and 5) the rates of diagnosis and of treatment substantially differ across countries.^[162]

Long term effects of stimulants prescribed for ADHD are largely unknown because of a dearth of long term studies.^[163] Some research raises questions about the long term effectiveness and side effects of medications used to treat ADHD.^[164]

[edit] See also

General Developmental disability Educational psychology Environmental health Feingold diet Hypothalamic-pituitary-adrenal axis List of attention-deficit hyperactivity disorder organizations CDR Computerized Assessment System

Related disorders Auditory processing disorder Bipolar disorder in children Sluggish cognitive tempo Dyslexia Controversy Anti-psychiatry Biopsychiatry controversy Chemical imbalance theory

[edit] References

[edit] Further reading

[edit] External links

• National Institute of Mental Health on ADHD
• "CG72 Attention deficit hyperactivity disorder (ADHD): full guideline" (PDF). NHS. 24 September 2008. http://www.nice.org.uk/nicemedia/pdf/CG72FullGuideline.pdf. Retrieved on 2008-10-08. 

v • d • e Attention-deficit hyperactivity disorder Main articles History · ADHD in adults · ADHD controversies · ADHD management · List of ADHD organizations · Social construct theory of ADHD · ADHD coaching Sub-types ADHD predominantly inattentive (ADHD-I, formerly ADD) · ADHD predominantly hyperactive (ADHD-H) · ADHD combined type (ADHD-C) Notable Publications Driven to Distraction (1994) · The International Consensus Statement on ADHD (2002) · Delivered from Distraction (2005) Notable Experts Stephen Faraone · Edward Hallowell · John Ratey · 19th Century: Alexander Crichton Relevant Drugs methylphenidate (Ritalin) · dextroamphetamine (Dexedrine) · mixed amphetamine salts (Adderall) · Non-stimulant: Atomoxetine (Strattera) · More... See also: Low arousal theory · Sluggish cognitive tempo · Hyperactivity · Sensory integration dysfunction · Hypokalemic sensory overstimulation · Deficits in Attention, Motor control and Perception

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