Attention deficit hyperactivity disorder

Attention-deficit/hyperactivity disorder
Classification and external resources
Children with ADHD find it more difficult to focus and to complete their schoolwork.
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) is a neurobehavioral disorder characterized by either significant difficulties of inattention or hyperactivity and impulsiveness or a combination of the two. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), symptoms emerge before seven years of age. There are three subtypes of the disorder which consist of it being predominantly inattentive (ADHD-PI or ADHD-I), predominantely hyperactive-impulsive (ADHD-HI or ADHD-H), or the two combined (ADHD-C). Oftentimes people refer to ADHD-PI as "attention deficit disorder" (ADD), however, the latter has not been officially accepted since the 1994 revision of the DSM. ADHD impacts school-aged children and results in restlessness, acting impulsively, and lack of focus which impairs their ability to learn properly.

It is the most commonly studied and diagnosed psychiatric disorder in children, affecting about 3 to 5 percent of children globally and is diagnosed in about 2 to 16 percent of school-aged children. It is a chronic disorder with 30 to 50 percent of those individuals diagnosed in childhood continuing to have symptoms into adulthood. Adolescents and adults with ADHD tend to develop coping mechanisms to compensate for some or all of their impairments. It is estimated that 4.7 percent of American adults live with ADHD. ADHD is diagnosed two to four times more frequently in boys than in girls. Its symptoms can be difficult to differentiate from other disorders, increasing the likelihood that the diagnosis of ADHD will be missed. In addition, most clinicians have not received formal training in the assessment and treatment of ADHD, in particular in adult patients. Standardized rating scales can be used for ADHD screening and assessment of the disorder's symptoms' severity.

ADHD management usually involves some combination of medications, behavior therapy, lifestyle changes, and counseling. Only children with severe ADHD symptoms should be considered for medication as a first-line treatment option. Medication therapy can also be considered for those with moderate ADHD symptoms who either refuse psychotherapeutic options or else fail to respond to psychotherapeutic input.

ADHD and its diagnosis and treatment have been considered controversial since the 1970s. The controversies have involved clinicians, teachers, policymakers, parents and the media. Topics include ADHD's causes, and the use of stimulant medications in its treatment. Most healthcare providers accept ADHD as a genuine disorder with debate in the scientific community centering mainly around how it is diagnosed and treated. The National Institute for Clinical Excellence, while acknowledging the controversy, states that the current treatments and methods of diagnosis are based on the dominant view of the academic literature.

Signs and symptoms

Children with ADHD tend to get distracted from schoolwork rather easily, and they often behave disruptively.

Inattention, hyperactivity, disruptive behavior and impulsivity are common in ADHD. Academic difficulties are also frequent. The symptoms are especially difficult to define because it is hard to draw a line at where normal levels of inattention, hyperactivity, and impulsivity end and clinically significant levels requiring intervention begin. To be diagnosed with ADHD, symptoms must be observed in two different settings for six months or more and to a degree that is greater than other children of the same age.

The symptom categories yield three potential classifications of ADHD—predominantly inattentive type, predominantly hyperactive-impulsive type, or combined type if criteria for both subtypes are met:

Predominantly inattentive type symptoms as listed by the U.S. National Institute of Mental Health may include:

• Be easily distracted, miss details, forget things, and frequently switch from one activity to another
• Have difficulty maintaining focus on one task
• Become bored with a task after only a few minutes, unless doing something enjoyable
• Have difficulty focusing attention on organizing and completing a task or learning something new or trouble completing or turning in homework assignments, often losing things (e.g., pencils, toys, assignments) needed to complete tasks or activities
• Not seem to listen when spoken to
• Daydream, become easily confused, and move slowly
• Have difficulty processing information as quickly and accurately as others
• Struggle to follow instructions.

Predominantly hyperactive-impulsive type symptoms may include:

• Fidget and squirm in their seats
• Talk nonstop
• Dash around, touching or playing with anything and everything in sight
• Have trouble sitting still during dinner, school, and story time
• Be constantly in motion
• Have difficulty doing quiet tasks or activities

and also these manifestations primarily of impulsivity:

• Be very impatient
• Blurt out inappropriate comments, show their emotions without restraint, and act without regard for consequences
• Have difficulty waiting for things they want or waiting their turns in games

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—and in the absence of significant interference or impairment, a diagnosis of ADHD is normally not appropriate. The core impairments are consistent even in different cultural contexts.

Some children, adolescents, and adults with ADHD have an increased risk of experiencing difficulties with social skills, such as social interaction and forming and maintaining friendships. About half of children and adolescents with ADHD experience rejection by their peers compared to 10-15 percent of non-ADHD children and adolescents. Training in social skills, behavioural modification and medication may have some limited beneficial effects. The most important factor in reducing emergence of later psychopathology, such as major depression, criminality, school failure, and substance use disorders is formation of friendships with people who are not involved in delinquent activities. Adolescents with ADHD are more likely to have difficulty making and keeping friends due to impairments in processing verbal and nonverbal language.

Handwriting difficulties seem to be common in children with ADHD. Delays in speech and language as well as motor development occur more commonly in the ADHD population. A 2009 study found that children with ADHD move around a lot because it helps them stay alert enough to complete challenging tasks.

Associated disorders

Inattention and hyperactive behavior are not necessarily the only problems in children with ADHD. ADHD exists alone in only about 1/3 of the children diagnosed with it. The combination of ADHD with other conditions can greatly complicate diagnosis and treatment. 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 and conduct disorder, which occur with ADHD at a rate of 50 percent and 20 percent respectively, are characterized by antisocial behaviors such as stubbornness, aggression, frequent temper tantrums, deceitfulness, lying, or stealing, inevitably linking these comorbid disorders with antisocial personality disorder (ASPD); about half of those with hyperactivity and ODD or CD develop ASPD in adulthood. However, modern brain imaging technology indicates that conduct disorder and ADHD are two distinct disorders.
• Borderline personality disorder, which was according to a study on 120 female psychiatric patients diagnosed and treated for BPD associated with ADHD in 70 percent of those cases.
• 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.
• Mood disorders (especially Bipolar disorder and Major depressive disorder). Boys diagnosed with the combined ADHD subtype have been shown to be more likely to suffer from a mood disorder.
• Bipolar disorder. Adults with ADHD sometimes have co-morbid bipolar disorder, which requires careful assessment in order to accurately diagnose and treat both conditions.
• Anxiety disorders, have been found to occur more commonly in the ADHD population.
• Obsessive-compulsive disorder. OCD can co-occur with ADHD and shares many of its characteristics.
• Substance use disorders. Adolescents and adults with ADHD are at a significantly increased risk of developing a substance abuse problem which can interfere with the evaluation and treatment of ADHD. The most commonly misused substances by the ADHD population are alcohol and cannabis; serious substance misuse problems should be treated first due to the serious risks and impairments that occur, with long-term alcohol misuse and long-term cannabis misuse and other drug misuse.

There is a strong association between persistent bed wetting and ADHD as well as dyspraxia with up to 50 percent of dyspraxics having ADHD. Multiple research studies have also found a significant association between ADHD and language delay. Anxiety and depression are some of the disorders that can accompany ADHD. 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 with ADHD often wish to have the ADHD treated first, because the response to treatment is quicker.

High IQ

There has been some controversy as to whether ADHD children with a high IQ have significant impairments. Research has shown that high IQ children with ADHD are more likely to repeat grades and have more social and functional impairments; more than half require additional academic support compared to children without ADHD. Additionally, more than half of high IQ ADHD people experience major depressive disorder or oppositional defiant disorder at some point in their lives. Generalised anxiety disorder, separation anxiety disorder and social phobia is also more common in high IQ ADHD individuals. There is some evidence that high IQ ADHD individuals are not at an increased risk of substance abuse and conduct disorder compared to low and average IQ ADHD young people. High IQ children and adolescents with ADHD can have their high intelligence level missed when standard testing is performed; high IQ ADHD people tend to require more comprehensive testing to detect their true intelligence level. High IQ ADHD children have a unique neuropsychological profile which typically shows a gap of 20 points or more between the verbal IQ and the performance IQ when tested on the Wechsler Intelligence Scale for Children; high IQ children without ADHD do not usually present with this sizable gap.

Cause

The specific causes of ADHD are not known. There are, however, a number of factors that may contribute to, or exacerbate ADHD. They include genetics, diet and the social and physical environments.

Genetics

Twin studies indicate that the disorder is highly heritable and that genetics are a factor in about 75 percent of all cases. Hyperactivity also seems to be primarily a genetic condition; however, other causes have been identified.

A large majority of ADHD cases may arise from a combination of various genes, many of which affect dopamine transporters. Candidate genes include DAT1, DRD4, DRD5, 5HTT, HTR1B, and SNAP25. There is also strong heterogeneity for the associations between ADHD and DAT1, DRD4, DRD5, dopamine beta hydroxylase, ADRA2A, 5HTT, TPH2, MAOA, and SNAP25. A common variant of a gene called LPHN3 is estimated to be responsible for about 9% of the incidence of ADHD, and ADHD cases where this gene is present are particularly responsive to stimulant medication.

Executive functions

Cognitive processes that regulate, control, and manage other cognitive processes are termed "executive functions" (EF). Examples of such regulated processes are planning, working memory, attention, inhibition, mental flexibility, and initiation and monitoring of actions. One of the most noticeable neuropsychologic theories of ADHD suggests that its symptoms arise from a primary deficit in executive functions (EF). A 2005 review found that groups with ADHD showed significant impairment on all EF tasks. The strongest effects were on measures of response inhibition, vigilance, working memory, and planning. However, the effect sizes were moderate and there were also individual differences. Not all individuals with ADHD show deficits in executive functioning; the criteria for an executive function deficit are met in 30–50% of children and adolescents with ADHD. Furthermore, deficits in EF are not unique to ADHD. For example, deficits in executive function are seen in individuals with oppositional defiant disorder and conduct disorder. One study found that 80% of individuals with ADHD was impaired in at least one EF task, compared to 50% for individuals without ADHD. The 2005 review concluded that deficits in certain executive functions play an important role in ADHD; however, "EF weaknesses are neither necessary nor sufficient to cause all cases of ADHD".

Evolution

See also: Hunter vs. farmer hypothesis

At more than 1 percent of the population, researchers have proposed that the high prevalence of ADHD may be due to natural selection having favoured ADHD, possibly because the individual traits may be beneficial on their own, and only become dysfunctional when these traits combine to form ADHD. The high prevalence of ADHD may in part be because women in general are more attracted to males who are risk takers, thereby promoting ADHD in the gene pool.

Further evidence that hyperactivity might be evolutionarily beneficial was put forth in a 2006 study finding that it may carry specific benefits for certain forms of society. In these societies, those with ADHD are hypothesized to have been more proficient in tasks involving risk, competition, and/or unpredictable behavior (i.e. exploring new areas, finding new food sources, etc.), where these societies may have benefited from confining impulsive or unpredictable behavior to a small subgroup. In these situations, ADHD would have been beneficial to society as a whole even while severely detrimental to the individual. More recent research suggests that because ADHD is more common in mothers who are anxious or stressed that ADHD is a mechanism of priming the child with the necessary traits for a stressful or dangerous environment, such as increased impulsivity and explorative behaviour etc. A genetic variant associated with ADHD (DRD4 48bp VNTR 7R allele) has been found to be at higher frequency in more nomadic populations and those with more of a history of migration. Consistent with this, another group of researchers observed that the health status of nomadic Ariaal men was higher if they had the ADHD associated genetic variant (7R alleles). However in recently sedentary (non-nomadic) Ariaal those with 7R alleles seemed to have slightly worse health.

Environmental

ADHD is predominantly a genetic disorder with environmental factors contributing a small role to the etiology of ADHD. Twin studies have shown that ADHD is largely genetic with 76 percent of the phenotypic variance being explained by inherited genetic factors. Alcohol intake during pregnancy can cause the child to have a fetal alcohol spectrum disorder which can include symptoms similar to ADHD. Exposure to tobacco smoke during pregnancy impairs normal development of the feotus including the central nervous system and can increase the risk of the child being diagnosed with ADHD. Many children exposed to tobacco do not develop ADHD or else only have mild symptoms which do not reach the threshold of a diagnosis of ADHD. A combination of a genetic vulnerability to developing ADHD as well as the toxic developmental effects of tobacco on the foetus explain why some children exposed to tobacco smoke in utero develop ADHD and others don't. Children exposed to lead, even relatively low levels of lead develop neurocognitive deficits which resemble ADHD and these children can fulfill the diagnostic criteria for ADHD. There is also some evidence that exposure to polychlorinated biphenyls during childhood causes developmental damage and can cause ADHD type symptoms which are the diagnosed as ADHD. Exposure to the organophosphate insecticides chlorpyrifos and dialkyl phosphate is associated with an increased risk of ADHD. However, the evidence is not definitive as 5 of 17 studies failed to find an association.

Very low birth weight, premature birth and exceptional early adversity increase the risk of the child having ADHD. At least 30 percent of children who experience a paediatric traumatic brain injury develop ADHD. Infections during pregnancy, at birth, and in early childhood are linked to an increased risk of developing ADHD. These include various viruses (measles, varicella, rubella, enterovirus 71) and streptococcal bacterial infection.

Diet

Main article: Diet and attention deficit hyperactivity disorder

Concerns were first raised by Benjamin Feingold, a paediatric allergist that food colourings and additives may affect children's behaviour in 1973. There is evidence suggesting that some food colourings may make some children hyperactive. However, the evidence for a link between food colourings and hyperactive behaviour remains uncertain. The FDA interpreted the evidence as being inconclusive as to whether food colours caused hyperactivity or not. The FDA review of food colours has been criticised for only doing a very narrow investigation into food colourings and their possible association with causing hyperactivity instead of investigating their possible effect on neurobehaviour in general. It is possible that certain food colourings act as a trigger for ADHD symptoms in subgroup of children who have a genetic vulnerability. The U.K, followed by the European Union took regulatory action on food colourings due to concerns about their possible adverse effects in children. According to the Food Standards Agency, the food regulatory agency in the UK, food manufacturers were encouraged to voluntarily phase out the use of most artificial food colors by the end of 2009. Sunset yellow FCF (E110), quinoline yellow (E104), carmoisine (E122), allura red (E129), tartrazine (E102) and ponceau 4R (E124) are collectively called the "Southampton six". Following the FSA’s actions, the European Commission ruled that any food products containing the contentious colourings must display warning labels on their packaging by 2010.

Social

The World Health Organization states that the diagnosis of ADHD can represent family dysfunction or inadequacies in the educational system rather than individual psychopathology. Other 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. Researchers have found behavior typical of ADHD in children who have suffered violence and emotional abuse. Individuals with posttraumatic stress syndrome (PTSD) show deficits in executive functions and in attention, and children with PTSD can be misdiagnosed with ADHD.

Social construct theory of ADHD

Main article: Social construct theory of ADHD

Social construction theory states that it is societies that determine where the line between normal and abnormal behavior is drawn. Thus society members including physicians, parents, teachers, and others are the ones who determine which diagnostic criteria are applied and, thus, determine the number of people affected. This is exemplified in the fact that the DSM IV arrives at levels of ADHD three to four times higher than those obtained with use of the ICD 10. Thomas Szasz, a proponent of this theory, has argued that ADHD was "invented and not discovered."

Pathophysiology

Diagram of the human brain

The pathophysiology of ADHD is unclear and there are a number of competing theories. Research on children with ADHD has shown a general reduction of brain volume, but with a proportionally greater reduction in the volume of the left-sided prefrontal cortex. These findings suggest that the core ADHD features of inattention, hyperactivity, and impulsivity may reflect frontal lobe dysfunction, but other brain regions in particular the cerebellum have also been implicated. Neuroimaging studies in ADHD have not always given consistent results and as of 2008 are used only for research and not diagnostic purposes. A 2005 review of published studies involving neuroimaging, neuropsychological genetics, and neurochemistry found converging lines of evidence to suggest that four connected frontostriatal regions play a role in the pathophysiology of ADHD: The lateral prefrontal cortex, dorsal anterior cingulate cortex, caudate, and putamen.

It should be noted that stimulant medication itself may affect growth factors of the central nervous system.

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.

Previously it was thought that the elevated number of dopamine transporters seen in ADHD patients was part of the pathophysiology of ADHD but it now appears that the reason for elevated striatal dopamine transporter density in ADHD individuals is due to neuroadaptations occurring due to the continuous exposure to stimulants such as methylphenidate or dexamphetamine as the body tries to counter-act the effects of the stimulants by developing a tolerance to the stimulant medications. One interpretation of dopamine pathway tracers is that the biochemical "reward" mechanism works for those with ADHD only when the task performed is inherently motivating; low levels of dopamine raise the threshold at which someone can maintain focus on a task that is otherwise boring. There is evidence that people with ADHD have a low arousal threshold and compensate for this with increased stimuli, which in turn results in disruption of attentional capacity and an increase in hyperactive behaviour. The reason for this is due to abnormalities in how the dopamine system in central nervous system responds to stimuli.

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 the decreased thickness observed in certain brain regions. While the main study in question used age-matched controls, it did not provide information on height and weight of the subjects. These variables it has been argued could account for the regional brain size differences rather than ADHD itself. They believe many neuroimaging studies are oversimplified in both popular and scientific discourse and given undue weight despite deficiencies in experimental methodology.

Diagnosis

ADHD is diagnosed via a psychiatric assessment; to rule out other potential causes or comorbidities, physical examination, radiological imaging, and laboratory tests may be used.

In North America, the DSM-IV criteria are often the basis for a diagnosis, while European countries usually use the ICD-10. If the DSM-IV criteria are used, rather than the ICD-10, a diagnosis of ADHD is 3–4 times more likely. Factors other than those within the DSM or ICD, however, have been found to affect the diagnosis in clinical practice. For example, the youngest children in a class are much more likely to be diagnosed as having ADHD compared to their older counterparts in the same year. This is because these children may behave more hyperactively, not because they have ADHD, but because they are younger and developmentally behind their classmates. It is estimated that about 20 percent of children given a diagnosis of ADHD are misdiagnosed because of the month they were born.

Children who display the behavioural symptoms of ADHD but who do not have any significant functional impairments compared to their age-matched peers cannot be diagnosed as having the psychiatric disorder, ADHD.

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

Classification

ADHD may be seen as one or more continuous traits found normally throughout the general population. It is a developmental disorder in which certain traits such as impulse control lag in development. Using magnetic resonance imaging of the prefrontal cortex, this developmental lag has been estimated to range from 3 to 5 years. However, the definition of ADHD is based on behaviour and it does not imply a neurological disease. ADHD is classified as a disruptive behavior disorder along with oppositional defiant disorder, conduct disorder and antisocial personality disorder.

The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) classifies ADHD according to the predominance of symptoms of:

1. Inattention;
2. Hyperactivity–impulsivity;
3. or a combination of both (Combined type).

This subdivision is based on presence of at least six out of nine long-term maladaptive symptoms (lasting at least 6 months) of either inattention, hyperactivity–impulsivity, or both. Thus, a child who is diagnosed with the inattention subtype may also show signs of hyperactivity–impulsivity, and vice-versa. To be considered, the symptoms must have appeared before the age of 6, manifest in more than one environment (e.g. at home and at school or work), and not be better explained by another mental disorder.

Most children with ADHD have the combined type. Children with the inattention subtype are less likely to act out or have difficulties getting along with other children. They may sit quietly, but without paying attention to what they are doing. Therefore, the child may be overlooked, and parents and teachers may not notice symptoms of ADHD.

DSM-IV

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 is a combination of the two other ADHD subtypes.
2. ADHD Predominantly Inattentive Type presents with symptoms including being easily distracted, forgetful, daydreaming, disorganisation, poor concentration, and difficulty completing tasks.
3. ADHD, Predominantly Hyperactive-Impulsive Type presents with excessive fidgetiness and restlessness, hyperactivity, difficulty waiting and remaining seated, immature behaviour; destructive behaviors may also be present.

For a diagnosis of ADHD to be made the signs must not be due to the course of a Pervasive Developmental Disorder, Schizophrenia, or other Psychotic Disorder. The signs are not better accounted for by another mental disorder (such as Mood Disorder, Anxiety Disorder, Dissociative Identity Disorder, or a Personality Disorder).

ICD-10

In the tenth edition of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) the signs of ADHD are given the name "hyperkinetic disorders". When a conduct disorder (as defined by ICD-10) is present, the condition is referred to as "hperkinetic 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".

Other 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:

• The use of explicit criteria for the diagnosis using the DSM-IV-TR.
• The importance of obtaining information about the child’s signs 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 signs must have been present prior to the age of seven. Questioning parents or guardians as to how the person behaved and developed as a child also forms part of the clinical assessment of the individual; a family history of ADHD also adds weight to a diagnosis of adult ADHD due the strong heritability of ADHD. While the core symptoms of ADHD are similar in children and adults they often present differently in adults than in children, for example excessive physical activity seen in children may present as feelings of restlessness and constant mental activity in adults.

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.

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.

Differential

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

Medical conditions that must be excluded as causing the ADHD symptoms include: hypothyroidism, anemia, lead poisoning, chronic illness, hearing or vision impairment, substance abuse, medication side-effects, sleep disorders and child abuse, and cluttering (tachyphemia) among others.

As with 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. 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.

Behavioral manifestations of sleepiness in children range from the classic ones (yawning, rubbing eyes), to externalizing behaviors (impulsivity, hyperactivity, aggressiveness), to mood lability and inattentiveness. Many sleep disorders are important causes of symptoms that may overlap with the cardinal symptoms of ADHD; children with ADHD should be regularly and systematically assessed for sleep problems.

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). A study in the Netherlands compared two groups of unmedicated 6-12-year-olds, all of them with "rigorously diagnosed ADHD". 87 of them had problems getting to sleep, 33 had no sleep problems. The larger group had a significantly later dim light melatonin onset (DLMO) than did the children with no sleep problems.

Management

Main article: Attention deficit hyperactivity disorder management

Methods of treatment often involve some combination of Positive behavior support (PBS), life-style changes, counseling, and medication. A 2005 study found that medical management and behavioral treatment is the most effective ADHD management strategy, followed by medication alone, and then behavioral treatment. While medication has been shown to improve behavior when taken over the short term, they have not been shown to alter long-term outcomes. Medications have at least some effect in about 80% of people. Dietary modifications may also be of benefit.

Psychosocial

The evidence is strong for the effectiveness of behavioral treatments in ADHD. It is recommended first line in those who have mild symptoms and in preschool-aged children. Psychological therapies used include psychoeducational input, behavior therapy, cognitive behavioral therapy (CBT), interpersonal psychotherapy (IPT), family therapy, school-based interventions, social skills training, parent management training, neurofeedback, and nature exposure. Parent training and education have been found to have short-term benefits. There is a deficiency of good research on the effectiveness of family therapy for ADHD, but the evidence that exists shows that it is comparable in effectiveness to treatment as usual in the community and is superior to medication placebo. Several ADHD specific support groups exist as informational sources and to help families cope with challenges associated with dealing with ADHD.

Medication

methylphenidate (Ritalin) 10 mg tablets

Stimulant medications are the medical treatment of choice. There are a number of non-stimulant medications, such as atomoxetine, that may be used as alternatives. There are no good studies of comparative effectiveness between various medications, and there is a lack of evidence on their effects on academic performance and social behaviors. While stimulants and atomoxetine are generally safe, there are side-effects and contraindications to their use. Medications are not recommended for preschool children, as their long-term effects in such young people are unknown. There is very little data on the long-term benefits or adverse effects of stimulants for ADHD. Any drug used for ADHD may have adverse drug reactions such as psychosis and mania, though methylphenidate-induced psychosis is uncommon. Regular monitoring of individuals receiving long-term stimulant therapy for possible treatment emergent psychosis has been recommended. Tolerance to the therapeutic effects of stimulants can occur, and abrupt withdrawal is not recommended. People with ADHD have an increased risk of substance abuse, and stimulant medications reduce this risk. Stimulant medications in and of themselves however have the potential for abuse and dependence. Guidelines on when to use medications vary internationally, with the UK's National Institute of Clinical Excellence, for example, recommending use only in severe cases, while most United States guidelines recommend medications in nearly all cases. Deficiency in zinc is more commonly found in ADHD children compared to other children. There is evidence that zinc supplementation can benefit ADHD children who have low zinc levels.

Prognosis

Children diagnosed with ADHD have significant difficulties in adolescence, regardless of treatment. In the United States, 37 percent of those with ADHD do not get a high school diploma even though many of them will receive special education services. A 1995 briefing citing a 1994 book review says the combined outcomes of the expulsion and dropout rates indicate that almost half of all ADHD students never finish high school. Also in the US, less than 5 percent of individuals with ADHD get a college degree compared to 28 percent of the general population. The proportion of children meeting the diagnostic criteria for ADHD drops by about 50 percent over three years after the diagnosis. This occurs regardless of the treatments used and also occurs in untreated children with ADHD. ADHD persists into adulthood in about 30 to 50 percent of cases. Those affected are likely to develop coping mechanisms as they mature, thus compensating for their previous ADHD.

Epidemiology

Percent of United States youth 4–17 ever diagnosed with ADHD as of 2007

  14%–15.9%

  11%–13.9%

  9.6%–10.9%

  8.0%–9.5%

  5.6%–7.9%

Percent of United States youth 4–17 ever diagnosed with ADHD as of 2003

ADHD's global prevalence is estimated at 3 to 5 percent in people under the age of 19. There is, however, both geographical and local variability among studies. Children in North America appear to have a higher rate of ADHD than children in Africa and the Middle East. Published studies have found rates of ADHD as low as 2 percent and as high as 14 percent among school-aged children. The rates of diagnosis and treatment of ADHD are also much higher on the east cast of the United States than on its west coast. The frequency of the diagnosis differs between male children (10%) and female children (4%) in the United States. This difference between genders may reflect either a difference in susceptibility or that females with ADHD are less likely to be diagnosed than males.

Rates of ADHD diagnosis and treatment have increased in both the UK and the US 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 US 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.

In the UK in 2003 a prevalence of 3.6 percent is reported in male children and less than 1 percent is reported in female children.

History

Main article: History of attention-deficit hyperactivity disorder

Hyperactivity has long been part of the human condition. Sir Alexander Crichton describes "mental restlessness" in his book An inquiry into the nature and origin of mental derangement written in 1798. The terminology used to describe the symptoms of ADHD has gone through many changes over history including: "minimal brain damage", "minimal brain dysfunction" (or disorder), "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. The use of stimulants to treat ADHD was first described in 1937.

Society and culture

See also: List of notable individuals with attention-deficit hyperactivity disorder

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 2005. In this interview he spoke about postpartum depression and also referred to Ritalin and Adderall as being "street drugs" rather than as ADHD medication. In England Baroness Susan Greenfield, a leading neuroscientist, spoke out publicly in 2007 in the House of Lords about the need for a wide-ranging inquiry into the dramatic increase in the diagnosis of ADHD in the UK and possible causes following a BBC Panorama programme that highlighted US research (The Multimodal Treatment Study of Children with ADHD by the University of Buffalo) suggesting drugs are no better than other forms of therapy for ADHD in the long term. However, in 2010 the BBC Trust criticized the 2007 BBC Panorama programme for summarizing the US research as showing "no demonstrable improvement in children's behaviour after staying on ADHD medication for three years" when in actuality "the study found that medication did offer a significant improvement over time" although the long-term benefits of medication were found to be "no better than children who were treated with behaviour therapy."

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

Legal status of medications

Stimulants legal status was recently reviewed by several international organizations:

• Internationally, methylphenidate is a Schedule II drug under the Convention on Psychotropic Substances.
• In the United States, methylphenidate and amphetamines are classified as Schedule II controlled substances, the designation used for substances that have a recognized medical value but present a high likelihood for abuse because of their addictive potential.
• In the United Kingdom, methylphenidate is a controlled 'Class B' substance, and possession without prescription is illegal, with a sentence up to 14 years and/or an unlimited fine.
• In Australia, stimulants such as methylphenidate and dexamphetamine are Schedule 8 controlled poisons, and as a result have strict prescribing rules due to their potential for abuse.

Controversies

Main article: Attention-deficit hyperactivity disorder controversies

ADHD and its diagnosis and treatment have been considered controversial since the 1970s. The controversies have involved clinicians, teachers, policymakers, parents and the media. Opinions regarding ADHD range from not believing it exists at all to believing there are genetic and physiological bases for the condition as well as disagreement about the use of stimulant medications in treatment. Some sociologists consider ADHD to be a "classic example of the medicalization of deviant behavior, defining a previously nonmedical problem as a medical one". Most healthcare providers in U.S. accept that ADHD is a genuine disorder with debate in centering mainly around how it is diagnosed and treated.

The British Psychological Society said in a 1997 report that physicians and psychiatrists should not follow the American example of applying medical labels to such a wide variety of attention-related disorders: "The idea that children who don’t attend or who don’t sit still in school have a mental disorder is not entertained by most British clinicians." In 2009, the British Psychological Society, in collaboration with the Royal College of Psychiatrists, released a set of guidelines for the diagnosis and treatment of ADHD. In its guideline, it states that available evidence indicate that ADHD is a valid diagnosis and that medication should be the first-line treatment for adults, for children with severe ADHD, or for children with mild ADHD who do not respond to non-medication interventions. However, it states that the diagnosis lack any biological basis and that "[c]ontroversial issues surround changing thresholds applied to the definition of illness as new knowledge and treatments are developed and the extent to which it is acknowledged that clinical thresholds are socially and culturally influenced and determine how an individual's level of functioning within the 'normal cultural environment' is assessed". It further states that "the acceptable thresholds for impairment are partly driven by the contemporary societal view of what is an acceptable level of deviation from the norm."

Others have included that it may stem from a misunderstanding of the diagnostic criteria and how they are utilized by clinicians,teachers, policymakers, parents and the media. Debates center around key controversial issues; whether ADHD is a disability or merely a neurological description, the cause of the disorder, the changing of the diagnostic criteria, the rapid increase in diagnosis of ADHD, and the use of stimulants to treat the disorder. Possible long-term side-effects of stimulants and their usefulness are largely unknown because of a lack of long-term studies. Some research raises questions about the long-term effectiveness and side-effects of medications used to treat ADHD.

In 1998, the US National Institutes of Health (NIH) released a consensus statement on the diagnosis and treatment of ADHD. The statement, while recognizing that stimulant treatment is controversial, supports the validity of the ADHD diagnosis and the efficacy of stimulant treatment. It found controversy only in the lack of sufficient data on long-term use of medications, and in the need for more research in many areas.

With a "wide variation in diagnosis across states, races, and ethnicities" some investigators suspect that factors other than neurological conditions play a role when the diagnosis of ADHD is made. Two studies published in 2010 suggest that the diagnosis is more likely to be made in the younger children within a grade; the authors propose that such a misdiagnosis of ADHD within a grade may be due to different states of maturity and may lead to potentially inappropriate treatment. A further study involving a million children in British Columbia (Canada) published in 2012 using data from 1997 to 2008 unambiguously confirmed the phenomenon, finding children born in December (the youngest) 39% more likely to be diagnosed with ADHD than those born in January (the oldest).

In adults

Main article: Adult attention deficit hyperactivity disorder

Between 2 and 5 percent of adults have ADHD. Between one-third, and up to 80 percent of the children diagnosed with ADHD continue having symptoms well into adulthood. Many adults, however, remain untreated. 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.They often have such associated psychiatric comorbidities as depression, anxiety disorder, substance abuse, or a learning disability. 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.

References

Bibliography

• Jennifer Erkulwater; Rick Mayes; Catherine Bagwell (2009). Medicating Children: ADHD and Pediatric Mental Health. Cambridge: Harvard University Press. p. 5. ISBN 0-674-03163-6.

Further reading

• Faraone Stephen V (2005). "The scientific foundation for understanding attention-deficit/hyperactivity disorder as a valid psychiatric disorder". Eur Child Adolesc Psychiatry 14 (1): 1–10. doi:10.1007/s00787-005-0429-z. PMID 15756510.
• Faraone, Stephen, V. (2003). Straight Talk about Your Child's Mental Health: What to Do When Something Seems Wrong. New York: Guilford Press. OCLC 51630861.
• Hartmann, Thom (2003). The Edison gene: ADHD and the gift of the hunter child. Rochester, Vt: Park Street Press. ISBN 0-89281-128-5.
• Matlen, Terry (2005). Survival Tips for Women with AD/HD. ISBN 1-886941-59-9. OCLC 56729582.
• Millichap, J. Gordon (2010). Attention Deficit Hyperactivity Disorder Handbook: A Physician’s Guide to ADHD. New York: Springer. ISBN 978-1-4419-1396-8. http://books.google.com/books?id=CTWLzYgQWqEC&lpg=PP1&pg=PP1#v=onepage&q=&f=false.
• Southall, Angela (2007). The Other Side of ADHD:Attention Deficit Hyperactivity Disorder Exposed and Explained. Radcliffe Publishing Ltd. ISBN 1-84619-068-1. http://books.google.com/?id=AKXhThWgvyYC&pg=PA41&lpg=PA41&dq=barkley+drug+company+funding. Retrieved 2009-05-02.

External links

• National Institute of Mental Health on ADHD
• "CG72 Attention deficit hyperactivity disorder (ADHD): full guideline" (PDF). NHS. 9 March 2009. http://www.nice.org.uk/nicemedia/pdf/ADHDFullGuideline.pdf. Retrieved 2009-01-08.
• New Zealand MOH Guidelines for the Assessment and Treatment of Attention-Deficit/Hyperactivity Disorder