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Asperger's syndrome

 
Dictionary: As·per·ger's syndrome   (ăs'pər-gərz) pronunciation
 
n.

A pervasive developmental disorder, usually of childhood, characterized by impairments in social interactions and repetitive behavior patterns.

[After Hans Asperger (1906–1980), Austrian pediatrician.]


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Neurological Disorder:

Asperger's disorder

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Definition

Asperger's disorder, which is also called Asperger's syndrome (AS) or autistic psychopathy, belongs to a group of childhood disorders known as pervasive developmental disorders (PDDs) or autistic spectrum disorders. The essential features of Asperger's disorder are severe social interaction impairment and restricted, repetitive patterns of behavior and activities. It is similar to autism, but children with Asperger's do not have the same difficulties in acquiring language that children with autism have.

In the mental health professional's diagnostic handbook, the Diagnostic and Statistical Manual of Mental Disorders fourth edition text revised, or DSM-IV-TR, Asperger's disorder is classified as a developmental disorder of childhood.

Description

AS was first described by Hans Asperger, an Austrian psychiatrist, in 1944. Asperger's work was unavailable in English before the mid-1970s; as a result, AS was often unrecognized in English-speaking countries until the late 1980s. Before DSM-IV (published in 1994) there was no officially agreed-upon definition of AS. In the words of ICD-10, the European equivalent of the DSM-IV, Asperger's is "a disorder of uncertain nosological validity." (Nosological refers to the classification of diseases.) There are three major reasons for this lack of clarity: differences between the diagnostic criteria used in Europe and those used in the United States; the fact that some of the diagnostic criteria depend on the observer's interpretation rather than objective measurements; and the fact that the clinical picture of Asperger's changes as the child grows older.

Asperger's disorder is one of the milder pervasive developmental disorders. Children with AS learn to talk at the usual age and often have above-average verbal skills. They have normal or above-normal intelligence and the ability to feed or dress themselves and take care of their other daily needs. The distinguishing features of AS are problems with social interaction, particularly reciprocating and empathizing with the feelings of others; difficulties with nonverbal communication (such as facial expressions); peculiar speech habits that include repeated words or phrases and a flat, emotionless vocal tone; an apparent lack of "common sense"; a fascination with obscure or limited subjects (for example, the parts of a clock or small machine, railroad schedules, astronomical data, etc.) often to the exclusion of other interests; clumsy and awkward physical movements; and odd or eccentric behaviors (hand wringing or finger flapping; swaying or other repetitious whole-body movements; watching spinning objects for long periods of time).

Demographics

Although the incidence of AS has been variously estimated between 0.024% and 0.36% of the general population in North America and northern Europe, further research is required to determine its true rate of occurrence—especially because the diagnostic criteria have been defined so recently. In addition, no research regarding the incidence of AS has been done on the populations of developing countries, and nothing is known about the incidence of the disorder in different racial or ethnic groups.

With regard to gender differences, AS appears to be much more common in boys. Dr. Asperger's first patients were all boys, but girls have been diagnosed with AS since the 1980s. One Swedish study found the male/female ratio to be 4:1; however, the World Health Organization's ICD-10 classification gives the male to female ratio as 8 to 1.

Causes and symptoms

There is some indication that AS runs in families, particularly in families with histories of depression and bipolar disorder. Asperger noted that his initial group of patients had fathers with AS symptoms. Knowledge of the genetic profile of the disorder continues to be quite limited, however.

In addition, about 50% of AS patients have a history of oxygen deprivation during the birth process, which has led to the hypothesis that the disorder is caused by damage to brain tissue before or during childbirth. Another cause that has been suggested is an organic defect in the functioning of the brain.

Research studies have made no connection between Asperger's disorder and childhood trauma, abuse or neglect.

In young children, the symptoms of AS typically include problems picking up social cues and understanding the basics of interacting with other children. The child may want friendships but find him- or herself unable to make friends.

Most children with Asperger's are diagnosed during the elementary school years because the symptoms of the disorder become more apparent at this point. They include:

  • Poor pragmatic language skills. This phrase means that the child does not use the right tone or volume of voice for a specific context, and does not understand that using humorous or slang expressions also depends on social context.
  • Problems with hand-eye coordination and other visual skills
  • Problems making eye contact with others
  • Learning difficulties, which may range from mild to severe
  • Tendency to become absorbed in a particular topic and not know when others are bored with conversation about it. At this stage in their education, children with AS are likely to be labeled as "nerds."
  • Repetitive behaviors. These include such behaviors as counting a group of coins or marbles over and over; reciting the same song or poem several times; buttoning and unbuttoning a jacket repeatedly; etc.

Adolescence is one of the most painful periods of life for young people with Asperger's, because social interactions are more complex in this age group and require more subtle social skills. Some boys with AS become frustrated trying to relate to their peers and may become aggressive. Both boys and girls with the disorder are often quite naive for their age and easily manipulated by "street-wise" classmates. They are also more vulnerable than most youngsters to peer pressure.

Little research has been done regarding adults with AS. Some have serious difficulties with social and occupational functioning, but others are able to finish their schooling, join the workforce, and marry and have families.

Diagnosis

Currently, there are no blood tests or brain scans that can be used to diagnose AS. Until DSM-IV (1994), there was no "official" list of symptoms for the disorder, which made its diagnosis both difficult and inexact. Although most children with AS are diagnosed between five and nine years of age, many are not diagnosed until adulthood. Misdiagnoses are common; AS has been confused with such other neurological disorders as Tourette's syndrome, or with attention-deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), or obsessive-compulsive disorder (OCD). Some researchers think that AS may overlap with some types of learning disability, such as the nonverbal learning disability (NLD) syndrome identified in 1989.

The inclusion of AS as a separate diagnostic category in DSM-IV was justified on the basis of a large international field trial of over a thousand children and adolescents. Nevertheless, the diagnosis of AS is also complicated by confusion with such other diagnostic categories as "high-functioning (IQ higher than 70) autism" or HFA, and "schizoid personality disorder of childhood." Unlike schizoid personality disorder of childhood, AS is not an unchanging set of personality traits—AS has a developmental dimension. AS is distinguished from HFA by the following characteristics:

  • Later onset of symptoms (usually around three years of age)
  • Early development of grammatical speech; the AS child's verbal IQ (scores on verbal sections of standardized intelligence tests) is usually higher than performance IQ (how well the child performs in school). The reverse is usually true for autistic children
  • Less severe deficiencies in social and communication skills
  • Presence of intense interest in one or two topics
  • Physical clumsiness and lack of coordination
  • Family is more likely to have a history of the disorder
  • Lower frequency of neurological disorders
  • More positive outcome in later life

DSM-IV-TR criteria for Asperger's disorder

The DSM-IV-TR specifies the following diagnostic criteria for AS:

  • The child's social interactions are impaired in at least two of the following ways: markedly limited use of nonverbal communication (facial expressions, for example); lack of age-appropriate peer relationships; failure to share enjoyment, interests, or accomplishment with others; lack of reciprocity (turn-taking) in social interactions.
  • The child's behavior, interests, and activities are characterized by repetitive or rigid patterns, such as an abnormal preoccupation with one or two topics, or with parts of objects; repetitive physical movements; or rigid insistence on certain routines and rituals.
  • The patient's social, occupational, or educational functioning is significantly impaired.
  • The child has normal age-appropriate language skills.
  • The child has normal age-appropriate cognitive skills, self-help abilities, and curiosity about the environment.
  • The child does not meet criteria for another specific PDD or schizophrenia.

To establish the diagnosis, the child psychiatrist or psychologist would observe the child, and would interview parents, possibly teachers, and the affected child (depending on the child's age), and would gather a comprehensive medical and social history.

Other diagnostic scales and checklists

Other instruments that have been used to identify children with AS include Gillberg's criteria, a six-item list compiled by a Swedish researcher that specifies problems in social interaction, a preoccupying narrow interest, forcing routines and interests on the self or others, speech and language problems, nonverbal communication problems, and physical clumsiness; and the Australian Scale for Asperger's Syndrome, a detailed multi-item questionnaire developed in 1996.

Brain imaging findings

Current research has linked only a few structural abnormalities of the brain to AS. Findings include abnormally large folds in the brain tissue in the left frontal region, abnormally small folds in the operculum (a lid-like structure composed of portions of three adjoining brain lobes), and damage to the left temporal lobe (a part of the brain containing a sensory area associated with hearing). The first single photon emission tomography (SPECT) study of an AS patient found a lower-than-normal supply of blood to the left parietal area of the brain, an area associated with bodily sensations. Brain imaging studies on a larger sample of AS patients is the next stage of research.

Treatment team

The treatment team needed for a child with Asperger's syndrome will vary based on the specifics and the severity of the child's disabilities. Pediatricians, developmental pediatricians, neurologists, and child psychiatrists can all play a part in the diagnosis and the treatment planning for a child with Asperger's syndrome. Physical therapy, occupational therapy, speech and language therapy, individual and group behavioral therapy, and psychoeducational planning are all crucial to helping a child with Asperger's syndrome progress optimally.

Treatments

There is no cure for AS and no prescribed treatment regimen for all AS patients. Specific treatments are based on the individual's symptom pattern.

Medications

Many children with AS do not require any medication. For those who do, the drugs that are recommended most often include psychostimulants (methylphenidate, pemoline), clonidine, or one of the tricyclic antidepressants (TCAs) for hyperactivity or inattention; beta blockers, neuroleptics (antipsychotic medications), or lithium (lithium carbonate) for anger or aggression; selective serotonin reuptake inhibitors (SSRIs) or TCAs for rituals (repetitive behaviors) and preoccupations; and SSRIs or TCAs for anxiety symptoms. One alternative herbal remedy that has been tried with AS patients is St. John's wort.

Psychotherapy

AS patients often benefit from individual psychotherapy, particularly during adolescence, in order to cope with depression and other painful feelings related to their social difficulties. Many children with AS are also helped by group therapy, which brings them together with others facing the same challenges. There are therapy groups for parents as well.

Therapists who are experienced in treating children with Asperger's disorder have found that the child should be allowed to proceed slowly in forming an emotional bond with the therapist. Too much emotional intensity at the beginning may be more than the child can handle. Behavioral approaches seem to work best with these children. Play therapy can be helpful in teaching the child to recognize social cues as well as lowering the level of emotional tension.

Adults with AS are most likely to benefit from individual therapy using a cognitive-behavioral approach, although many also attend group therapy. Some adults have been helped by working with speech therapists on their pragmatic language skills. A relatively new approach called behavioral coaching has been used to help adults with Asperger's learn to organize and set priorities for their daily activities.

Prognosis

AS is a lifelong but stable condition. The prognosis for children with AS is generally good as far as intellectual development is concerned, although few school districts are equipped to meet the special social needs of this group of children. Adults with AS appear to be at greater risk of depression than the general population. In addition, some researchers believe that people with AS have an increased risk of a psychotic episode (a period of time during which the affected person loses touch with reality) in adolescence or adult life.

Special concerns

Educational considerations

Most AS patients have normal or above-normal intelligence, and are able to complete their education up through the graduate or professional school level. Many are unusually skilled in music or good in subjects requiring rote memorization. On the other hand, the verbal skills of children with AS frequently cause difficulties with teachers, who may not understand why these "bright" children have social and communication problems. Some AS children are dyslexic; others have difficulty with writing or mathematics. In some cases, AS children have been mistakenly put in special programs either for children with much lower levels of functioning, or for children with conduct disorders. AS children do best in structured learning situations in which they learn problem-solving and social skills as well as academic subjects. They frequently need protection from the teasing and bullying of other children, and often become hypersensitive to criticism by their teenage years. One approach that has been found helpful at the high-school level is to pair the adolescent with AS with a slightly older teenager who can serve as a mentor. The mentor can "clue in" the younger adolescent about the slang, dress code, cliques, and other "facts of life" at the local high school.

Employment

Adults with AS are productively employed in a wide variety of fields, including the learned professions. They do best, however, in jobs with regular routines or occupations that allow them to work in isolation. In large companies, employers or supervisors and workplace colleagues may need some information about AS in order to understand the new employee's "eccentricities."

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.

"Psychiatric Conditions in Childhood and Adolescence." Section 19, Chapter 274. In The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, M.D., and Robert Berkow, M.D. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Thoene, Jess G., ed. Physicians' Guide to Rare Diseases. Montvale, NJ: Dowden Publishing Company, 1995.

World Health Organization (WHO). The ICD-10 Classification of Mental and Behavioural Disorders. Geneva: WHO, 1992.

PERIODICALS

Bishop, D. V. M. "Autism, Asperger's Syndrome & Semantic-Pragmatic Disorder: Where Are the Boundaries?" British Journal of Disorders of Communication 24 (1989): 107–121.

Gillberg, C. "The Neurobiology of Infantile Autism." Journal of Child Psychology and Psychiatry 29 (1988): 257–266.

ORGANIZATIONS

Autism Research Institute. 4182 Adams Avenue, San Diego, CA 92116.

Families of Adults Afflicted with Asperger's Syndrome (FAAAS). P.O. Box 514, Centerville, MA 02632. www.faaas.org.

National Association of Rare Disorders (NORD). P.O. Box 8923, New Fairfield, CT 06812-8923. (800) 999-NORD or (203) 746-6518.

Yale-LDA Social Learning Disabilities Project. Yale Child Study Center, New Haven, CT. The Project is looking for study subjects with PDDs between the ages of 8 and 24, including AS patients. Contact person: Sanno Zack at (203) 785-3488 or Sanno.Zack@yale.edu. www.info.med.Yale.edu/chldstdy/autism.

OTHER

American Academy of Child & Adolescent Psychiatry (AACAP). "Asperger's Disorder." AACAP Facts For Families Pamphlet #69. Washington, DC: American Academy of Child & Adolescent Psychiatry, 1999.


Rebecca Frey, Ph.D.


 
Wikipedia: Asperger syndrome
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Asperger syndrome
Classification and external resources
Seated boy facing 3/4 away from camera, looking at a ball-and-stick model of a molecular structure. The model is made of colored magnets and steel balls.
People with AS often display intense interests, such as this boy's fascination with molecular structure.
ICD-10 F84.5
ICD-9 299.80
OMIM 608638
DiseasesDB 31268
MedlinePlus 001549
eMedicine ped/147 
MeSH F03.550.325.100

Asperger syndrome is an autism spectrum disorder (ASD), and people with it therefore show significant difficulties in social interaction, along with stereotypies and other restricted and repetitive patterns of behavior and interests. It differs from other ASDs by its relative preservation of linguistic and cognitive development. Although not required for diagnosis, physical clumsiness and atypical use of language are frequently reported.[1][2]

Asperger syndrome (AS) is also called Asperger's syndrome, Asperger (or Asperger's) disorder, or just Asperger's. It is named after the Austrian pediatrician Hans Asperger who, in 1944, described children in his practice who lacked nonverbal communication skills, demonstrated limited empathy with their peers, and were physically clumsy.[3] Fifty years later, AS was standardized as a diagnosis, but questions about many aspects remain.[4] For example, there is lingering doubt about the distinction between AS and high-functioning autism (HFA);[5] partly because of this, the prevalence of AS is not firmly established. The exact cause is unknown, although research supports the likelihood of a genetic basis; brain imaging techniques have not identified a clear common pathology.[1]

There is no single treatment for Asperger syndrome, and the effectiveness of particular interventions is supported by only limited data.[1] Intervention is aimed at improving symptoms and function. The mainstay of management is behavioral therapy, focusing on specific deficits to address poor communication skills, obsessive or repetitive routines, and physical clumsiness.[6] Most individuals with AS improve over time, but difficulties with communication, social adjustment and independent living continue into adulthood.[4] Some researchers and people with AS have advocated a shift in attitudes toward the view that AS is a difference, rather than a disability that must be treated or cured.[7]

Contents

Classification

Asperger syndrome is one of the autism spectrum disorders (ASD) or pervasive developmental disorders (PDD), which are a spectrum of psychological conditions that are characterized by abnormalities of social interaction and communication that pervade the individual's functioning, and by restricted and repetitive interests and behavior. Like other psychological development disorders, ASD begins in infancy or childhood, has a steady course without remission or relapse, and has impairments that result from maturation-related changes in various systems of the brain.[8] ASD, in turn, is a subset of the broader autism phenotype (BAP), which describes individuals who may not have ASD but do have autistic-like traits, such as social deficits.[9] Of the other four ASD forms, autism is the most similar to AS in signs and likely causes but its diagnosis requires impaired communication and allows delay in cognitive development, Rett syndrome and childhood disintegrative disorder share several signs with autism but may have unrelated causes, and pervasive developmental disorder not otherwise specified (PDD-NOS) is diagnosed when the criteria for a more specific disorder are unmet.[10]

The extent of the overlap between AS and high-functioning autism (HFA—autism unaccompanied by mental retardation) is unclear.[5][11][12] The current ASD classification is to some extent an artifact of how autism was discovered,[13] and may not reflect the true nature of the spectrum.[14] A panel session at a 2008 diagnosis-related autism research planning conference noted problems with the classification of AS as a distinct subgroup of ASD, and two of three breakout groups recommended eliminating AS as a separate diagnosis in future versions of the Diagnostic and Statistical Manual of Mental Disorders and of the International Statistical Classification of Diseases and Related Health Problems.[15]

Characteristics

A pervasive developmental disorder, Asperger syndrome is distinguished by a pattern of symptoms rather than a single symptom. It is characterized by qualitative impairment in social interaction, by stereotyped and restricted patterns of behavior, activities and interests, and by no clinically significant delay in cognitive development or general delay in language.[16] Intense preoccupation with a narrow subject, one-sided verbosity, restricted prosody, and physical clumsiness are typical of the condition, but are not required for diagnosis.[5]

Social interaction

The lack of demonstrated empathy is possibly the most dysfunctional aspect of Asperger syndrome.[2] Individuals with AS experience difficulties in basic elements of social interaction, which may include a failure to develop friendships or to seek shared enjoyments or achievements with others (for example, showing others objects of interest), a lack of social or emotional reciprocity, and impaired nonverbal behaviors in areas such as eye contact, facial expression, posture, and gesture.[1]

Unlike those with autism, people with AS are not usually withdrawn around others; they approach others, even if awkwardly. For example a person with AS may engage in a one-sided, long-winded speech about a favorite topic, while misunderstanding or not recognizing the listener's feelings or reactions, such as a need for privacy or haste to leave.[5] This social awkwardness has been called "active but odd".[1] This failure to react appropriately to social interaction may appear as disregard for other people's feelings, and may come across as insensitive.[5]

The cognitive ability of children with AS often allows them to articulate social norms in a laboratory context,[1] where they may be able to show a theoretical understanding of other people's emotions; however, they typically have difficulty acting on this knowledge in fluid, real-life situations.[5] People with AS may analyze and distill their observation of social interaction into rigid behavioral guidelines, and apply these rules in awkward ways, such as forced eye contact, resulting in a demeanor that appears rigid or socially naive. Childhood desire for companionship can become numbed through a history of failed social encounters.[1]

The hypothesis that individuals with AS are predisposed to violent or criminal behavior has been investigated but is not supported by data.[1][17] More evidence suggests children with AS are victims rather than victimizers.[18] A 2008 review found that an overwhelming number of reported violent criminals with AS had coexisting psychiatric disorders such as schizoaffective disorder.[19]

Restricted and repetitive interests and behavior

People with Asperger syndrome often display behavior, interests, and activities that are restricted and repetitive and are sometimes abnormally intense or focused. They may stick to inflexible routines, move in stereotyped and repetitive ways, or preoccupy themselves with parts of objects.[16]

Pursuit of specific and narrow areas of interest is one of the most striking features of AS.[1] Individuals with AS may collect volumes of detailed information on a relatively narrow topic such as dinosaurs or members of congress, without necessarily having genuine understanding of the broader topic.[1][5] For example, a child might memorize camera model numbers while caring little about photography.[1] This behavior is usually apparent by grade school, typically age 5 or 6 in the United States.[1] Although these special interests may change from time to time, they typically become more unusual and narrowly focused, and often dominate social interaction so much that the entire family may become immersed. Because narrow topics often capture the interest of children, this symptom may go unrecognized.[5]

Stereotyped and repetitive motor behaviors are a core part of the diagnosis of AS and other ASDs.[20] They include hand movements such as flapping or twisting, and complex whole-body movements.[16] These are typically repeated in longer bursts and look more voluntary or ritualistic than tics, which are usually faster, less rhythmical and less often symmetrical.[21]

Speech and language

Although individuals with Asperger syndrome acquire language skills without significant general delay and their speech typically lacks significant abnormalities, language acquisition and use is often atypical.[5] Abnormalities include verbosity, abrupt transitions, literal interpretations and miscomprehension of nuance, use of metaphor meaningful only to the speaker, auditory perception deficits, unusually pedantic, formal or idiosyncratic speech, and oddities in loudness, pitch, intonation, prosody, and rhythm.[1]

Three aspects of communication patterns are of clinical interest: poor prosody, tangential and circumstantial speech, and marked verbosity. Although inflection and intonation may be less rigid or monotonic than in autism, people with AS often have a limited range of intonation: speech may be unusually fast, jerky or loud. Speech may convey a sense of incoherence; the conversational style often includes monologues about topics that bore the listener, fails to provide context for comments, or fails to suppress internal thoughts. Individuals with AS may fail to monitor whether the listener is interested or engaged in the conversation. The speaker's conclusion or point may never be made, and attempts by the listener to elaborate on the speech's content or logic, or to shift to related topics, are often unsuccessful.[5]

Children with AS may have an unusually sophisticated vocabulary at a young age and have been colloquially called "little professors", but have difficulty understanding figurative language and tend to use language literally.[1] Children with AS appear to have particular weaknesses in areas of nonliteral language that include humor, irony, and teasing. Although individuals with AS usually understand the cognitive basis of humor they seem to lack understanding of the intent of humor to share enjoyment with others.[12] Despite strong evidence of impaired humor appreciation, anecdotal reports of humor in individuals with AS seem to challenge some psychological theories of AS and autism.[22]

Other

Individuals with Asperger syndrome may have signs or symptoms that are independent of the diagnosis, but can affect the individual or the family. These include differences in perception and problems with motor skills, sleep, and emotions.

Individuals with AS often have excellent auditory and visual perception.[23] Children with ASD often demonstrate enhanced perception of small changes in patterns such as arrangements of objects or well-known images; typically this is domain-specific and involves processing of fine-grained features.[24] Conversely, compared to individuals with high-functioning autism, individuals with AS have deficits in some tasks involving visual-spatial perception, auditory perception, or visual memory.[1] Many accounts of individuals with AS and ASD report other unusual sensory and perceptual skills and experiences. They may be unusually sensitive or insensitive to sound, light, touch, texture, taste, smell, pain, temperature, and other stimuli, and they may exhibit synesthesia;[25] these sensory responses are found in other developmental disorders and are not specific to AS or to ASD. There is little support for increased fight-or-flight response or failure of habituation in autism; there is more evidence of decreased responsiveness to sensory stimuli, although several studies show no differences.[26]

Hans Asperger's initial accounts[1] and other diagnostic schemes[27] include descriptions of physical clumsiness. Children with AS may be delayed in acquiring skills requiring motor dexterity, such as riding a bicycle or opening a jar, and may seem to move awkwardly or feel "uncomfortable in their own skin". They may be poorly coordinated, or have an odd or bouncy gait or posture, poor handwriting, or problems with visual-motor integration.[1][5] They may show problems with proprioception (sensation of body position) on measures of apraxia (motor planning disorder), balance, tandem gait, and finger-thumb apposition. There is no evidence that these motor skills problems differentiate AS from other high-functioning ASDs.[1]

Children with AS are more likely to have sleep problems, including difficulty in falling asleep, frequent nocturnal awakenings, and early morning awakenings.[28][29] AS is also associated with high levels of alexithymia, which is difficulty in identifying and describing one's emotions.[30] Although AS, lower sleep quality, and alexithymia are associated, their causative relationship is unclear.[29]

As with other forms of ASD, parents of children with AS have higher levels of stress.[31]

Causes

Hans Asperger described common symptoms among his patients' family members, especially fathers, and research supports this observation and suggests a genetic contribution to Asperger syndrome. Although no specific gene has yet been identified, multiple factors are believed to play a role in the expression of autism, given the phenotypic variability seen in this group of children.[1][32] Evidence for a genetic link is the tendency for AS to run in families and an observed higher incidence of family members who have behavioral symptoms similar to AS but in a more limited form (for example, slight difficulties with social interaction, language, or reading).[6] Most research suggests that all autism spectrum disorders have shared genetic mechanisms, but AS may have a stronger genetic component than autism.[1] There is probably a common group of genes where particular alleles render an individual vulnerable to developing AS; if this is the case, the particular combination of alleles would determine the severity and symptoms for each individual with AS.[6]

A few ASD cases have been linked to exposure to teratogens (agents that cause birth defects) during the first eight weeks from conception. Although this does not exclude the possibility that ASD can be initiated or affected later, it is strong evidence that it arises very early in development.[33] Many environmental factors have been hypothesized to act after birth, but none has been confirmed by scientific investigation.[34]

Mechanism

Asperger syndrome appears to result from developmental factors that affect many or all functional brain systems, as opposed to localized effects.[35] Although the specific underpinnings of AS or factors that distinguish it from other ASDs are unknown, and no clear pathology common to individuals with AS has emerged,[1] it is still possible that AS's mechanism is separate from other ASD.[36] Neuroanatomical studies and the associations with teratogens strongly suggest that the mechanism includes alteration of brain development soon after conception.[33] Abnormal migration of embryonic cells during fetal development may affect the final structure and connectivity of the brain, resulting in alterations in the neural circuits that control thought and behavior.[37] Several theories of mechanism are available; none is likely to provide a complete explanation.[38]

Monochrome fMRI image of a horizontal cross-section of a human brain. A few regions, mostly to the rear, are highlighted in orange and yellow.
Functional magnetic resonance imaging provides some evidence for both underconnectivity and mirror neuron theories.[39][40]

The underconnectivity theory hypothesizes underfunctioning high-level neural connections and synchronization, along with an excess of low-level processes.[39] It maps well to general-processing theories such as weak central coherence theory, which hypothesizes that a limited ability to see the big picture underlies the central disturbance in ASD.[41] A related theory—enhanced perceptual functioning—focuses more on the superiority of locally oriented and perceptual operations in autistic individuals.[42]

The mirror neuron system (MNS) theory hypothesizes that alterations to the development of the MNS interfere with imitation and lead to Asperger's core feature of social impairment.[40][43] For example, one study found that activation is delayed in the core circuit for imitation in individuals with AS.[44] This theory maps well to social cognition theories like the theory of mind, which hypothesizes that autistic behavior arises from impairments in ascribing mental states to oneself and others,[45] or hyper-systemizing, which hypothesizes that autistic individuals can systematize internal operation to handle internal events but are less effective at empathizing by handling events generated by other agents.[46]

Other possible mechanisms include serotonin dysfunction[47] and cerebellar dysfunction.[48]

Screening

Parents of children with Asperger syndrome can typically trace differences in their children's development to as early as 30 months of age.[32] Developmental screening during a routine check-up by a general practitioner or pediatrician may identify signs that warrant further investigation.[1][6] The diagnosis of AS is complicated by the use of several different screening instruments,[6][27] including the Asperger Syndrome Diagnostic Scale (ASDS), Autism Spectrum Screening Questionnaire (ASSQ), Childhood Asperger Syndrome Test (CAST), Gilliam Asperger's Disorder Scale (GADS), Krug Asperger's Disorder Index (KADI),[49] and the Autism Spectrum Quotient (AQ; with versions for children,[50] adolescents[51] and adults[52]). None have been shown to reliably differentiate between AS and other ASDs.[1]

Diagnosis

Standard diagnostic criteria require impairment in social interaction, and repetitive and stereotyped patterns of behavior, activities and interests, without significant delay in language or cognitive development. Unlike the international standard,[8] U.S. criteria also require significant impairment in day-to-day functioning.[16] Other sets of diagnostic criteria have been proposed by Szatmari et al.[53] and by Gillberg and Gillberg.[54]

Diagnosis is most commonly made between the ages of four and eleven.[1] A comprehensive assessment involves a multidisciplinary team[2][6][55] that observes across multiple settings,[1] and includes neurological and genetic assessment as well as tests for cognition, psychomotor function, verbal and nonverbal strengths and weaknesses, style of learning, and skills for independent living.[6] The current "gold standard" in diagnosing ASDs combines clinical judgment with the Autism Diagnostic Interview-Revised (ADI-R)—a semistructured parent interview—and the Autism Diagnostic Observation Schedule (ADOS)—a conversation and play-based interview with the child.[4] Delayed or mistaken diagnosis can be traumatic for individuals and families; for example, misdiagnosis can lead to medications that worsen behavior.[55] Many children with AS are initially misdiagnosed with attention-deficit hyperactivity disorder (ADHD).[1] Diagnosing adults is more challenging, as standard diagnostic criteria are designed for children and the expression of AS changes with age;[56] adult diagnosis requires painstaking clinical examination and thorough medical history gained from both the individual and other people who know the person, focusing on childhood behavior.[57] Conditions that must be considered in a differential diagnosis include other ASDs, the schizophrenia spectrum, ADHD, obsessive compulsive disorder, major depressive disorder, semantic pragmatic disorder, nonverbal learning disorder,[55] Tourette syndrome,[21] stereotypic movement disorder and bipolar disorder.[32]

Underdiagnosis and overdiagnosis are problems in marginal cases. The cost of screening and diagnosis and the challenge of obtaining payment can inhibit or delay diagnosis. Conversely, the increasing popularity of drug treatment options and the expansion of benefits has motivated providers to overdiagnose ASD.[58] There are indications AS has been diagnosed more frequently in recent years, partly as a residual diagnosis for children of normal intelligence who do not have autism but have social difficulties.[59] In 2006, it was reported to be the fastest-growing psychiatric diagnosis in Silicon Valley children; also, there is a predilection for adults to self-diagnose it.[60] There are questions about the external validity of the AS diagnosis. That is, it is unclear whether there is a practical benefit in distinguishing AS from HFA and from PDD-NOS;[59] the same child can receive different diagnoses depending on the screening tool.[6] The debate about distinguishing AS from HFA is partly due to a tautological dilemma where disorders are defined based on severity of impairment, so that studies that appear to confirm differences based on severity are to be expected.[61]

Management

Asperger syndrome treatment attempts to manage distressing symptoms and to teach age-appropriate social, communication and vocational skills that are not naturally acquired during development,[1] with intervention tailored to the needs of the individual child, based on multidisciplinary assessment.[62] Although progress has been made, data supporting the efficacy of particular interventions are limited.[1][63]

Therapies

The ideal treatment for AS coordinates therapies that address core symptoms of the disorder, including poor communication skills and obsessive or repetitive routines. While most professionals agree that the earlier the intervention, the better, there is no single best treatment package.[6] AS treatment resembles that of other high-functioning ASDs, except that it takes into account the linguistic capabilities, verbal strengths, and nonverbal vulnerabilities of individuals with AS.[1] A typical program generally includes:[6]

Of the many studies on behavior-based early intervention programs, most are case studies of up to five participants, and typically examine a few problem behaviors such as self-injury, aggression, noncompliance, stereotypies, or spontaneous language; unintended side effects are largely ignored.[68] Despite the popularity of social skills training, its effectiveness is not firmly established.[69] A randomized controlled study of a model for training parents in problem behaviors in their children with AS showed that parents attending a one-day workshop or six individual lessons reported fewer behavioral problems, while parents receiving the individual lessons reported less intense behavioral problems in their AS children.[70] Vocational training is important to teach job interview etiquette and workplace behavior to older children and adults with AS, and organization software and personal data assistants to improve the work and life management of people with AS are useful.[1]

Medications

No medications directly treat the core symptoms of AS.[66] Although research into the efficacy of pharmaceutical intervention for AS is limited,[1] it is essential to diagnose and treat comorbid conditions.[2] Deficits in self-identifying emotions or in observing effects of one's behavior on others can make it difficult for individuals with AS to see why medication may be appropriate.[66] Medication can be effective in combination with behavioral interventions and environmental accommodations in treating comorbid symptoms such as anxiety disorder, major depressive disorder, inattention and aggression.[1] The atypical neuroleptic medications risperidone and olanzapine have been shown to reduce the associated symptoms of AS;[1] risperidone can reduce repetitive and self-injurious behaviors, aggressive outbursts and impulsivity, and improve stereotypical patterns of behavior and social relatedness. The selective serotonin reuptake inhibitors (SSRIs) fluoxetine, fluvoxamine and sertraline have been effective in treating restricted and repetitive interests and behaviors.[1][2][32]

Care must be taken with medications; abnormalities in metabolism, cardiac conduction times, and an increased risk of type 2 diabetes have been raised as concerns with these medications,[71][72] along with serious long-term neurological side effects.[68] SSRIs can lead to manifestations of behavioral activation such as increased impulsivity, aggression and sleep disturbance.[32] Weight gain and fatigue are commonly reported side effects of risperidone, which may also lead to increased risk for extrapyramidal symptoms such as restlessness and dystonia[32] and increased serum prolactin levels.[73] Sedation and weight gain are more common with olanzapine,[72] which has also been linked with diabetes.[71] Sedative side-effects in school-age children[74] have ramifications for classroom learning. Individuals with AS may be unable to identify and communicate their internal moods and emotions or to tolerate side effects that for most people would not be problematic.[75]

Prognosis

There is some evidence that as many as 20% of children with AS "grow out" of it, and fail to meet the diagnostic criteria as adults.[4] As of 2006, no studies addressing the long-term outcome of individuals with Asperger syndrome are available and there are no systematic long-term follow-up studies of children with AS.[5] Individuals with AS appear to have normal life expectancy but have an increased prevalence of comorbid psychiatric conditions such as major depressive disorder and anxiety disorder that may significantly affect prognosis. Although social impairment is lifelong, outcome is generally more positive than with individuals with lower functioning autism spectrum disorders;[1] for example, ASD symptoms are more likely to diminish with time in children with AS or HFA.[76] Although most students with AS/HFA have average mathematical ability and test slightly worse in mathematics than in general intelligence, some are gifted in mathematics[77] and AS has not prevented some adults from major accomplishments such as winning the Nobel Prize.[78]

Children with AS may require special education services because of their social and behavioral difficulties although many attend regular education classes.[5] Adolescents with AS may exhibit ongoing difficulty with self care, organization and disturbances in social and romantic relationships; despite high cognitive potential, most young adults with AS remain at home, although some do marry and work independently.[1] The "different-ness" adolescents experience can be traumatic.[79] Anxiety may stem from preoccupation over possible violations of routines and rituals, from being placed in a situation without a clear schedule or expectations, or from concern with failing in social encounters;[1] the resulting stress may manifest as inattention, withdrawal, reliance on obsessions, hyperactivity, or aggressive or oppositional behavior.[65] Depression is often the result of chronic frustration from repeated failure to engage others socially, and mood disorders requiring treatment may develop.[1] Clinical experience suggests the rate of suicide may be higher among those with AS, but this has not been confirmed by systematic empirical studies.[80]

Education of families is critical in developing strategies for understanding strengths and weaknesses;[2] helping the family to cope improves outcomes in children.[18] Prognosis may be improved by diagnosis at a younger age that allows for early interventions, while interventions in adulthood are valuable but less beneficial.[2] There are legal implications for individuals with AS as they run the risk of exploitation by others and may be unable to comprehend the societal implications of their actions.[2]

Epidemiology

Prevalence estimates vary enormously. A 2003 review of epidemiological studies of children found prevalence rates ranging from 0.03 to 4.84 per 1,000, with the ratio of autism to Asperger syndrome ranging from 1.5:1 to 16:1;[81] combining the average ratio of 5:1 with a conservative prevalence estimate for autism of 1.3 per 1,000 suggests indirectly that the prevalence of AS might be around 0.26 per 1,000.[82] Part of the variance in estimates arises from differences in diagnostic criteria. For example, a relatively small 2007 study of 5,484 eight-year-old children in Finland found 2.9 children per 1,000 met the ICD-10 criteria for an AS diagnosis, 2.7 per 1,000 for Gillberg and Gillberg criteria, 2.5 for DSM-IV, 1.6 for Szatmari et al., and 4.3 per 1,000 for the union of the four criteria. Boys seem to be more likely to have AS than girls; estimates of the sex ratio range from 1.6:1 to 4:1, using the Gillberg and Gillberg criteria.[83]

Anxiety disorder and major depressive disorder are the most common conditions seen at the same time; comorbidity of these in persons with AS is estimated at 65%.[1] Depression is common in adolescents and adults; children are likely to present with ADHD.[84] Reports have associated AS with medical conditions such as aminoaciduria and ligamentous laxity, but these have been case reports or small studies and no factors have been associated with AS across studies.[1] One study of males with AS found an increased rate of epilepsy and a high rate (51%) of nonverbal learning disorder.[85] AS is associated with tics, Tourette syndrome, and bipolar disorder, and the repetitive behaviors of AS have many similarities with the symptoms of obsessive-compulsive disorder and obsessive-compulsive personality disorder.[86] Although many of these studies are based on psychiatric clinic samples without using standardized measures, it seems reasonable to conclude that comorbid conditions are relatively common.[4]

History

Named after the Austrian pediatrician Hans Asperger (1906–80), Asperger syndrome is a relatively new diagnosis in the field of autism.[87] In 1944, Asperger described four children in his practice[2] who had difficulty in integrating themselves socially. The children lacked nonverbal communication skills, failed to demonstrate empathy with their peers, and were physically clumsy. Asperger called the condition "autistic psychopathy" and described it as primarily marked by social isolation.[6] Unlike today's AS, autistic psychopathy could be found in people of all levels of intelligence, including those with mental retardation.[88] In the context of the Nazi eugenics policy of sterilizing and killing social deviants and the mentally handicapped, Asperger passionately defended the value of autistic individuals, writing "We are convinced, then, that autistic people have their place in the organism of the social community. They fulfil their role well, perhaps better than anyone else could, and we are talking of people who as children had the greatest difficulties and caused untold worries to their care-givers."[3] Asperger also called his young patients "little professors",[3] and believed some would be capable of exceptional achievement and original thought later in life.[2] His paper was published during wartime and in German, so it was not widely read elsewhere.

Lorna Wing popularized the term Asperger syndrome in the English-speaking medical community in her 1981 publication[89] of a series of case studies of children showing similar symptoms,[87] and Uta Frith translated Asperger's paper to English in 1991.[3] Sets of diagnostic criteria were outlined by Gillberg and Gillberg in 1989 and by Szatmari et al. in the same year.[83] AS became a standard diagnosis in 1992, when it was included in the tenth edition of the World Health Organization's diagnostic manual, International Classification of Diseases (ICD-10); in 1994, it was added to the fourth edition of the American Psychiatric Association's diagnostic reference, Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).[6]

Hundreds of books, articles and websites now describe AS, and prevalence estimates have increased dramatically for ASD, with AS recognized as an important subgroup.[87] Whether it should be seen as distinct from high-functioning autism is a fundamental issue requiring further study.[2] There is little consensus among clinical researchers about the use of the terms Asperger's syndrome or Asperger's disorder, and there are questions about the empirical validation of the DSM-IV and ICD-10 criteria.[5]

Cultural aspects

People with Asperger syndrome may refer to themselves in casual conversation as aspies, coined by Liane Holliday Willey in 1999.[90] The word neurotypical (abbreviated NT) describes a person whose neurological development and state are typical, and is often used to refer to non-autistic people. The Internet has allowed individuals with AS to communicate and celebrate with each other in a way that was not previously possible because of their rarity and geographic dispersal. A subculture of aspies has formed. Internet sites like Wrong Planet have made it easier for individuals to connect.[7]

Autistic people have advocated a shift in perception of autism spectrum disorders as complex syndromes rather than diseases that must be cured. Proponents of this view reject the notion that there is an "ideal" brain configuration and that any deviation from the norm is pathological; they promote tolerance for what they call neurodiversity.[91] These views are the basis for the autistic rights and autistic pride movements.[92] There is a contrast between the attitude of adults with self-identified AS, who typically do not want to be cured and are proud of their identity, and parents of children with AS, who typically seek assistance and a cure for their children.[93]

Some researchers have argued that AS can be viewed as a different cognitive style, not a disorder or a disability.[7][94] In a 2002 paper, Simon Baron-Cohen wrote of those with AS, "In the social world there is no great benefit to a precise eye for detail, but in the worlds of math, computing, cataloguing, music, linguistics, engineering, and science, such an eye for detail can lead to success rather than failure." Baron-Cohen cited two reasons why it might still be useful to consider AS to be a disability: to ensure provision for legally required special support, and to recognize emotional difficulties from reduced empathy.[95] It has been argued that the genes for Asperger's combination of abilities have operated throughout recent human evolution and have made remarkable contributions to human history.[96]

Notes

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
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Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Asperger syndrome" Read more