Asperger syndrome

Asperger syndrome
Specialty	Psychiatry

Asperger syndrome (also Asperger's syndrome, Asperger's disorder, Asperger's, or AS) is one of five autism spectrum disorders (ASD) that are characterized by difficulties in social communication, interaction and reciprocity. AS is distinguished from other ASDs by linguistic and cognitive abilities that are relatively intact. Although motor clumsiness and the delayed acquisition of language capacity are not mentioned in standard diagnostic criteria, odd speech, language peculiarities and motor skills difficulties are frequently reported features of AS.

Asperger syndrome was named in honor of Hans Asperger who, in 1944, decribed children in his practice who appeared to have normal intelligence but lacked nonverbal communication skills, failed to demonstrate empathy with their peers, and were physically clumsy. In 1994, AS was recognized in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) as Asperger's Disorder.

The diagnosis of AS is complicated by the use of several different screening instruments and sets of diagnostic criteria. Less than two decades after the standardization of AS as a diagnosis, questions about many aspects of AS remain: the diagnostic validity of Asperger syndrome is disputed and there is lingering doubt about the distinction between AS and high-functioning autism (HFA). Experienced clinicians use characteristics beyond the diagnostic criteria to diagnose AS and to distinguish between AS and HFA. The prevalence of AS is not firmly established, due partly to the use of differing sets of diagnostic criteria. The exact cause of AS is unknown, although research supports the likelihood of a genetic contribution, and advanced brain imaging techniques have identified structural and functional differences in specific regions of the brain.

There is no single treatment for AS, and data supporting the effectiveness of particular interventions are limited; intervention is aimed at ameliorating symptoms and improving function. The mainstay of treatment is behavioral therapy, focusing on specific deficits to address poor communication skills, obsessive or repetitive routines, and clumsiness. Most individuals with AS can learn to cope with their differences, but may continue to need support to maintain an independent life. The deficits associated with AS may be debilitating and lifelong, but individuals who are able to excel in areas that are less dependent on social interaction may experience positive outcomes and one researcher suggests that people with AS may accomplish innovative research in fields such as computer science, mathematics and physics. Researchers and people with AS have contributed to a shift in attitudes, away from the notion that AS is a deviation from the norm that must be treated or cured, and towards the view that AS is a difference rather than a disability.

File:Asperger kl2.jpg

Hans Asperger described his young patients in the 1940s as "little professors".

Classification

Asperger syndrome is one of the five pervasive developmental disorders (PDD) or autism spectrum disorders (ASD), which are characterized by widespread abnormalities of social interaction and communication, and severely restricted interests and highly repetitive behavior. Of the other four autism spectrum disorders, autism is closest to AS in signs and likely causes; 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 are not met for a more specific disorder. Unlike autism, AS has no substantial delay in language or cognitive development under the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and World Health Organization ICD-10 diagnostic criteria.

The extent of the overlap between AS and high-functioning autism (HFA—autism unaccompanied by mental retardation) is unclear; there is significant debate over the difference between AS and HFA and whether they are distinct and separate disorders. Some clinicians deny that AS is differentiated from other autistic spectrum disorders and indicate that a "DSM-IV diagnosis of Asperger's disorder is unlikely or impossible". Instead they refer to Asperger's as HFA, or treat the diagnoses interchangeably, arguing that language delay is a difference in degree and not kind. While HFA has no standardized definition, and AS has several distinct definitions, diagnosticians and other clinicians often distinguish the two according to speech development. However, objective tests have yet to demonstrate the validity of this position, and at least one diagnostic guide takes the position that delayed speech may be a sign of AS. The diagnoses of AS or HFA are sometimes used interchangeably; the same child can receive different diagnoses depending on the screening tool the doctor uses. Some researchers argue that there should be no boundary between high-functioning autism and AS, and that the fact that some people do not start to produce speech until a later age is no reason to divide the two groups, since they are identical in the way they need to be treated. In some countries, diagnoses may be influenced by non-technical issues, such as availability of government benefits for one condition but not the other; clinicians may diagnose autism rather than the more correct Asperger's if that helps a child receive classroom support, government funding or services covered by insurance.

Canadian researcher Peter Szatmari writes that the current classification of the pervasive developmental disorders is "deeply unsatisfying to many parents, front-line clinicians, and academic researchers", and may not reflect the true nature of the conditions; he writes that the DSM-IV and ICD-10 focus on the idea that discrete biological entities exist within PDD, which "leads to a preoccupation with searching for cross-sectional differences between PDD subtypes, a strategy which has not been very useful in classification or in clinical practice".

Characteristics

AS is characterized in the DSM-IV by impairments in social interaction and restricted interests and behaviors. Intense preoccupation with a narrow subject, one-sided verbosity, restricted prosody and intonation, and motor clumsiness are typical of the condition, but are not required for a DSM-IV diagnosis; these features are included in other diagnostic schemes (see Diagnosis). Experienced clinicians use characteristics beyond the diagnostic criteria to distinguish between AS and HFA.

Describing the social interaction of individuals with AS, Harvard Medical School's Baskin, Sperber and Price have written that "the lack of empathy demonstrated by AS patients is possibly the most dysfunctional aspect of the syndrome". With respect to the restricted interests of those with AS, "one of the most striking features of individuals with AS is their passionate pursuit of specific areas of interest" (McPartland and Klin of the Yale Child Study Center). The DSM-IV does not specify language delays, but clinicians acknowledge abnormalities in speech and communication. Although individuals with AS "have considerable verbal ability they fail to utilize language appropriately in social interactions" (UCLA's Kasari and Rotheram-Fuller). Klin has written that "significant abnormalities of speech are not typical of individuals with AS", but "aspects of these individuals' communication patterns" are of clinical interest. Christopher Gillberg writes "Children with autism spectrum disorders, notably those with Asperger syndrome, have long been reported to suffer from the kind of motor clumsiness currently subsumed under the DCD [Developmental Coordination Disorder] label." "These are kids who talk before they walk," according to Fred Volkmar, the director of the Yale Child Study Center. "Words are their lifeline, and from a research perspective that's a critical observation that captures the difference from autism."

Social interaction

Individuals with Asperger syndrome experience difficulties in the basic elements of social interaction, which may be manifested in their impaired use of nonverbal behaviors such as eye contact, facial expressions, and bodily postures and gestures; a failure to develop friendships or enjoy spontaneous interests or achievements with others; or deficient social or emotional reciprocity. People with AS have a lower capacity for empathy, which was confirmed in a controlled study comparing AS and HFA individuals and has significant negative implications to people with AS.

Within the family, children with AS may or may not bond or show affection, while outside the family, they may make inappropriate attempts to socialize, leading to peer rejection. Dating and marriage present additional difficulties; men with AS may want to marry without an understanding of courtship. The concrete nature of emotional attachment for people with AS (for example, attachment to objects rather than people) may seem curious or be a cause of concern to others, although the opposite may occur: a person with AS may be unusually affectionate to significant others and not perceive or misinterpret signals from a partner.

People with AS may find themselves socially isolated, although unlike those with autism, they are not usually withdrawn around others; they approach others, even if awkwardly, for example by engaging in a one-sided, long-winded speech about an unusual topic while being insensitive to or unaware of the other person’s feelings or reactions, such as signs of boredom or wanting to leave. This failure to interpret the context of, or react appropriately to social interaction may appear as disregard for other people's feelings, and may come across as highly insensitive. However, the cognitive ability of people with AS sometimes permits them to articulate social norms in a laboratory context, where they may be able to describe social conventions and show a theoretical understanding of other people’s emotions, but have difficulty acting on this knowledge in real-life situations and fluid social interactions. People with AS may analyze and distill their observation of social interaction into rigid behavioral guidelines, yet apply these rules in ways that are awkward—such as forced eye contact—resulting in a demeanor that appears rigid or socially naïve.

Repetitive behaviors and restricted interests

People with AS display restricted repetitive and stereotyped patterns of behavior, interests, and activities that can include interests that are abnormal in intensity or focus, inflexible adherence to routines or rituals, stereotyped and repetitive motor mannerisms, or a preoccupation with parts of objects.

Individuals with AS may amass volumes of detailed information on their topics of special interest. While many children have developmentally appropriate interests in topics such as dinosaurs or trains, a child with AS may also be interested in transistors, subway tokens, deep fat fryers, or members of congress. These interests may have an exclusive, obsessive quality and an absence of genuine understanding of broader phenomena related to the topic. For example, "a child might be interested in memorizing the model numbers of antique cameras without any interest in photography". Asperger described good memory for trivial facts (occasionally even eidetic memory) in some of his patients; but this may involve more rote memorization than real understanding, despite occasional appearances to the contrary.

The passionate pursuit of peculiar and narrow interests is typically apparent by the time children with AS enter grade school, and may be at the expense of their developing typical peer relationships or pursuing other activities. The topic of interest may change over time, but often dominates social relationships, contributing to the social difficulties accompanying AS. The entire family may become immersed in the narrow topic of interest. Because topics such as dinosaurs and fictional characters often capture the interest of children, this symptom may go unrecognized, and may not be apparent until the interests become more unusual and focused over time.

Circumscribed interests may dominate a child’s social interaction, and the monologues characteristic of their preoccupations may alienate other children. Children with AS are "notoriously oblivious" to the effect their conversation is having on the listener, and their excessive enthusiasm to share the interest with others causes them to engage in a socially awkward manner that has been called "active but odd". Childhood desires for social companionship can be numbed through a history of failed social encounters.

Stereotyped and repetitive motor mannerisms may involve hand movements such as flapping or twisting, or complex whole-body movements; people with AS may display compulsive finger, hand, arm or leg movements, including tics and stims. Stereotypies are typically repeated in longer bursts and look more voluntary or ritualistic than tics, which are usually faster, less rhythmical and more often asymmetrical than stereotypies. Although there is overlap, experienced clinicians rarely have difficulty distinguishing tics from stereotypies.

Speech and language

Although language skills are not mentioned in the DSM-IV or ICD-10 diagnostic criteria, there is evidence that while children with AS acquire language on time, their use of language may be atypical; "speech and language peculiarities" and "odd speech" are included in other diagnostic schemes. Individuals with AS may demonstrate abnormal speech and language, including pedantic speech; oddities in pitch, intonation, prosody, and rhythm; literal interpretations and miscomprehension of nuance; a lack of sensitivity or an inability to use language in social contexts (for example, interrupting others or inserting irrelevant commentary and inappropriate personal remarks); unusually formal or idiosyncratic speech; verbosity, speech reflecting the idiosyncratic interests of the speaker or the use of metaphors meaningful only to the individual; selective mutism; and auditory discrimination issues, particularly when multiple people are speaking simultaneously.

According to Klin, at least three aspects of these individuals' 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 overly fast, jerky or loud. Speech may convey a sense of incoherence; although some of these cases may be symptomatic of a thought disorder, there is often a conversational style that includes monologues about topics of little or no interest the listener, a failure to provide context or background for comments, and a failure to suppress internal thoughts. Individuals with AS may talk incessantly about a favorite topic, and may fail to monitor whether the listener is interested or engaged in the conversation. The conclusion or point of long-winded monologues may never be made, and attempts by the listener to elaborate on the content or logic of the exchange, or to shift the focus to related topics, are often unsuccessful.

Children with AS may have an unusually sophisticated vocabulary at a young age (and have been colloquially referred to as "little professors") but have difficulty understanding metaphorical language and tend to use language literally. Autism researcher Tony Attwood gives the example of a girl with AS who answered the telephone and was asked, "Is Paul there?" Although Paul was in the house, he was not in the room with her, so she said "no" and hung up. The caller had to call back and explain that he meant for her to find Paul and have him pick up the telephone. Individuals with AS appear to have particular weaknesses in several areas of nonliteral language, including humor, irony and teasing. A study analyzing adolescents’ responses to cartoons found that individuals with AS and HFA had difficulty comprehending humor. Another study of young adults with AS found they understood ironic jokes less readily than typical controls and were poor at using social context to interpret conversational meaning; people with AS usually understand the cognitive basis of humor, but may lack understanding of the intent of humor—to "share enjoyment with others".

Other

Problems with motor skills are not part of the DSM-IV diagnostic criteria, but Asperger’s initial accounts and other diagnostic schemes include descriptions of motor clumsiness. Children with AS may be delayed in acquiring motor skills that require motor dexterity, such as bicycle riding or opening a jar, and may appear awkward or "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, visual–perceptual skills, and conceptual learning, while having "relative strengths in auditory and verbal skills and rote learning". Research also shows problems with proprioception and "deficits on measures of apraxia, balance tandem gait, and finger–thumb apposition". There is no evidence that these motor skills problems differentiate AS from other high-functioning ASDs.

Children with AS may be sensitive to sound (hyperacusis), touch, taste, sight, smell, pain, temperature, and the texture of foods; they may exhibit synesthesia, a neurologically based phenomenon in which the stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. A review of all controlled investigations published since 1960 showed that sensory symptoms were more frequent in children with autism, but there was little support for hyperarousal or habituation in autism; there was evidence of hyporesponsiveness to sensory stimuli, although many of these findings have not been replicated.

According to McPartland and Klin (2006), a unique neuropsychological profile has been described for AS and confirmed in a review of the literature; if verified, it could differentiate between AS and HFA and aid in differential diagnosis. Relative to HFA, people with AS have deficits in "fine and gross motor skills; visual motor integration; visual-spatial perception; nonverbal concept formation; and visual memory with preserved articulation, verbal output, auditory perception, vocabulary, and verbal memory". Verbal abilities are stronger than performance abilities and indicate weakness in visual–spatial organization and graphomotor skills. Most subjects with AS in another study had a "neuropsychologic profile consistent with a nonverbal learning disability". The literature review did not reveal consistent findings of "nonverbal weaknesses or increased spatial or motor problems relative to individuals with HFA", leading some researchers to argue that increased cognitive ability is evidenced in AS relative to HFA regardless of differences in verbal and nonverbal ability.

Alexithymia is a personality trait of people who have difficulty recognizing, processing and regulating emotions. Uta Frith reported that alexithymia overlaps with AS, and that at least half of the Asperger syndrome subjects in a study obtained scores that indicate severe impairment. Other researchers concur that both conditions are characterized by core disturbances in speech and language and social relationships and the limbic system and prefrontal cortex may be involved in both. Alexithymic traits in AS may be linked to depression or anxiety; the mediating factors are unknown and it is possible that alexithymia predisposes a person to anxiety.

Diagnosis

Asperger's Disorder is defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) by six main criteria:

1. qualitative impairment in social interaction
2. restricted, repetitive and stereotyped behaviors and interests
3. significant impairment in important areas of functioning
4. no significant delay in language development
5. no significant delay in cognitive development, self-help skills or adaptive behaviors (other than social interaction)
6. criteria are not met for another specific pervasive developmental disorder or schizophrenia.

Developmental screening during a routine check-up by a general practitioner or pediatrician may identify signs that warrant further investigation. This will require a comprehensive team evaluation to either confirm or exclude a diagnosis of AS. This team usually includes a psychologist, neurologist, psychiatrist, speech and language pathologist, occupational therapist and other professionals with expertise in diagnosing children with AS. Observation should occur across multiple settings; the social disability in AS may be more evident during periods when social expectations are unclear and children are free of adult direction. A comprehensive evaluation includes neurologic and genetic assessment, with in-depth cognitive and language testing to establish IQ and evaluate psychomotor function, verbal and nonverbal strengths and weaknesses, style of learning, and skills for independent living. An assessment of communication strengths and weaknesses includes the evaluation of nonverbal forms of communication (gaze and gestures); the use of non-literal language (metaphor, irony, absurdities and humor); patterns of speech inflection, stress and volume; pragmatics (turn-taking and sensitivity to verbal cues); and the content, clarity and coherence of conversation. Testing may include an audiological referral to exclude hearing impairment. The determination of whether there is a family history of autism spectrum conditions is important. A medical practitioner will diagnose on the basis of the test results and the child’s developmental history and current symptoms. Because multiple domains of functioning are involved, a multidisciplinary team approach is critical; an accurate assessment of the individual's strengths and weaknesses is more useful than a diagnostic label. Delayed or mistaken diagnosis is a serious problem that can be traumatic for individuals and families; diagnosis based solely on a neurological, speech and language, or educational attainment may yield only a partial diagnosis.

Parents of children with AS can typically trace differences in their children's development to as early as 30 months of age, although diagnosis is not made on average until the age of 11. By definition, children with AS develop language and self-help skills on schedule, so early signs may not be apparent and the condition may not be diagnosed until later childhood. Impairment in social interaction is sometimes not in evidence until a child attains an age at which these behaviors become important; social disabilities are often first noticed when children encounter peers in daycare or preschool. Diagnosis is most commonly made between the ages of four and eleven, and one study suggests that diagnosis cannot be rendered reliably before age four.

Asperger syndrome can be misdiagnosed as a number of other conditions, leading to medications that are unnecessary or even worsen behavior; the condition may be at the root of treatment-resistant mental illness in adults. Diagnostic confusion burdens individuals and families and may cause them to seek unhelpful therapies. Conditions that must be considered in a differential diagnosis include other pervasive developmental disorders (autism, PDD-NOS, childhood disintegrative disorder, Rett disorder), schizophrenia spectrum disorders (schizophrenia, schizotypal disorder, schizoid personality disorder), attention-deficit hyperactivity disorder, obsessive compulsive disorder, depression, semantic pragmatic disorder, multiple complex developmental disorder and nonverbal learning disorder. Tourette syndrome (TS) should also be considered in differential diagnosis: "It is in nonretarded, rigid individuals on the autistic spectrum, especially those with so-called Asperger syndrome, that differences with less severely affected individuals with TS and OCD may become blurred, or that both disorders may coexist." Other problems to be considered in the differential diagnosis include selective mutism, stereotypic movement disorder and bipolar disorder as well as traumatic brain injury or birth trauma, conduct disorder, Cornelia De Lange syndrome, fetal alcohol syndrome, fragile X syndrome, dyslexia, Fahr syndrome, hyperlexia, leukodystrophy, multiple sclerosis and Triple X syndrome.

Multiple sets of diagnostic criteria

The diagnosis of AS is complicated by the use of several different screening instruments. In addition to the DSM-IV and the similar World Health Organization ICD-10 criteria, other sets of diagnostic criteria for AS are the Szatmari et al. criteria and the Gillberg and Gillberg criteria.

Partial Diagnostic Criteria for Asperger Syndrome Adapted from Mattila et al. Blank = not defined by the criteria Substantial differences between criteria listed: all sub-sections of criteria not included
	DSM-IV	ICD-10	Gillberg	Szatmari
Language delay	No	No	Maybe
Cognitive development delay	No	No
Self-help skill delay	No	No
Social interaction impairment	Yes	Yes	Yes	Yes
– Impaired nonverbal communication	Maybe	Maybe	Yes	Yes
– Inadequate friendships	Maybe	Maybe	Maybe	Yes
Repetitive, stereotyped behavior	Yes	Yes	Yes
– All-absorbing interest	Maybe	Maybe	Yes
– Routines or rituals	Maybe	Maybe	Yes
Odd speech			Yes	Yes
Motor clumsiness		Maybe	Yes
Isolated special skills		Common
Clinically significant impairmenta	Yes
Exclusion of other disorder	Yesb	Yesc	No	Yesd
a Impairment in social, occupational, or other important areas of functioning b Does not meet criteria for another pervasive developmental disorder or schizophrenia c Not attributed to pervasive developmental disorder, schizotypal disorder, simple schizophrenia, reactive and disinhibited attachment disorder, obsessional personality disorder, obsessive compulsive disorder d Does not meet criteria for autistic disorder

The ICD-10 criteria are almost identical to DSM-IV: ICD-10 adds the statement that motor clumsiness is usual (although not necessarily a diagnostic feature); ICD-10 adds the statement that isolated special skills, often related to abnormal preoccupations, are common but are not required for diagnosis; and the DSM-IV requirement for clinically significant impairment in social, occupational, or other important areas of functioning is not included in ICD-10.

The Gillberg and Gillberg criteria are considered closest to Asperger's original description of the syndrome; the aggression, rage and abnormal prosody that defined Asperger's patients are not mentioned in any criteria. Compared with the DSM-IV and ICD-10 criteria, the requirements of normal early language and cognitive development are not mentioned by Szatmari et al., whereas speech delay is allowed in the Gillberg and Gillberg criteria. Szatmari et al. emphasize solitariness, and both Gillberg and Szatmari include "odd speech" and "language" in their criteria. Although Szatmari does not mention stereotyped behaviors, one of four described stereotyped functions is required by DSM-IV and ICD-10, and two are required by Gillberg and Gillberg. Abnormal responses to sensory stimuli are not mentioned in any diagnostic scheme, although they have been associated with AS. Because DSM-IV and ICD-10 exclude speech and language difficulties, these definitions exclude some of the original cases described by Hans Asperger. According to one researcher, the majority of individuals with AS do have speech and language abnormalities, and the recent DSM–IV says that "the occurrence of 'no clinically significant delays in language does not imply that individuals with Asperger Disorder have no problems with communication' (American Psychiatric Association, 2000, p. 80)".

The DSM-IV and ICD-10 diagnostic criteria have been criticized for being too broad and inadequate for assessing adults, overly narrow (particularly in relation to Hans Asperger's original description of individuals with AS), and vague; results of a large study in 2007 comparing the four sets of criteria point to a "huge need to reconsider the diagnostic criteria of AS". The study found complete overlap across all sets of diagnostic criteria in the impairment of social interaction with the exception of four cases not diagnosed by the Szatmari et al. criteria because of its emphasis on social solitariness. Lack of overlap was strongest in the language delay and odd speech requirements of the Gillberg and the Szatmari requirements relative to DSM-IV and ICD-10, and in the differing requirements regarding general delays.

Causes

See also: Causes of autism

Asperger described common symptoms among his patients' family members, especially fathers, and research supports this observation and suggests a genetic contribution to AS. 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. 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). Most research suggests that all autism spectrum disorders have shared genetic mechanisms, but AS may have a stronger genetic component than autism. 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. No gene has been identified for AS, although studies suggest specific genetic abnormalities: such as various types of chromosomal translocations in chromosomes 1, 5, 11, 13, 14, 15 and 17; autosomal fragile site, fragile X syndrome, fragile Y, and 21pþ. Anomalies in chromosome 22 were related to the diagnosis of autism and Asperger syndrome in five children. The distal tip of the long arm of the chromosome 22 contains the SHANK3 gene, which is thought to have a role in the maturation and maintenance of brain synapses. The deletion of this part of the chromosome (22q13 deletion syndrome) was found in low-functioning autistic subjects, and its duplication observed in a subject diagnosed with Asperger syndrome.

Environmental factors may interact with genetic influences to play a role in the cause of ASDs, but research has identified no consistent correlations. There is strong evidence that genetic factors play a major role in the causes of autism spectrum disorders, while none of the possible environmental causes has been confirmed by scientific investigation.

Mechanism

Brain imaging techniques have revealed structural and functional differences in specific regions of the brains of AS children; these are most likely caused by the abnormal migration of embryonic cells during fetal development, which affects the final structure and connectivity of the brain, resulting in alterations in the neural circuits that control thought and behavior. Although progress has been made, brain imaging technologies have failed to identify the specific underpinnings of AS or factors that distinguish it from other ASDs and no clear pathology common to individuals with AS has emerged. Functional MRI has provided interesting findings, but no convincing evidence reproducibly indicates differences among AS and other ASDs.

One study reported a reduction of brain activity in the frontal lobe of AS children when they were asked to respond to tasks that required them to use their judgment. These differences in activity were also seen when children were asked to respond to facial expressions. Another study, of brain function in adults with AS, revealed abnormal levels of some proteins and demonstrated a correlation between these levels and obsessive and repetitive behaviors. Possible differences in AS include: gray tissue anomalies, left temporal lobe damage, and left occipital hypoperfusion. Other possible causative mechanisms include serotonin dysfunction and cerebellar dysfunction. Differences in brain volumes—such as enlarged amygdala and hippocampus—have been linked to autism; the most robust findings are of the reduced size of the corpus callosum and rapid brain growth and increased brain volume in early childhood that normalizes in mid-childhood. Other research suggests abnormal right hemisphere functioning in AS, dysfunction in brain regions affecting social cognition, and problems with functional connectivity among separate brain regions.

Simon Baron-Cohen proposes a model for Asperger's that extends the extreme male brain theory, which hypothesizes that autism is an extreme case of the male brain, defined psychometrically as individuals in whom systemizing is better than empathizing. Hyper-systemizing hypothesizes that autistic individuals can systematize—that is, they can develop internal rules of operation to handle internal events—but are less effective at empathizing by handling events generated by other agents. This in turn is related to the earlier theory of mind, which hypothesizes that autistic behavior arises from an inability to ascribe mental states to oneself and others. Two studies showed that Asperger subjects had a second-order theory of mind; compared to younger or more impaired autistic individuals, they were able to understand problems of the type "Peter thinks that Jane thinks that ..." although their explanationns of their solutions did not use mental states. There is some evidence that the mind-reading capacity of children in the higher-functioning range of the autistic spectrum are intact.

Treatment

See also: Autism therapies

The goal of treatment is the development of age-appropriate social, communication and vocational abilities, and the successful management of distressing symptoms, aiming to teach through explicit instruction the skills that are not naturally acquired during development. Intervention should be tailored to the needs of the individual child, based on multidisciplinary assessment. Although progress has been made, data supporting the efficacy of particular interventions are limited.

The ideal treatment for AS coordinates therapies that address the three core symptoms of the disorder: poor communication skills, obsessive or repetitive routines, and physical clumsiness. While most professionals agree that the earlier the intervention, the better, there is no single best treatment package. 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. A typical treatment program generally includes:

• the training of social skills for more effective interpersonal interactions;
• cognitive behavioral therapy to improve the management of anxiety or explosive emotions, and to reduce the prevalence of obsessive interests and repetitive routines;
• medication, for coexisting conditions such as depression and anxiety;
• occupational or physical therapy to assist with poor sensory integration and motor coordination;
• specialized speech therapy, to help with the pragmatics of the "give and take" of normal conversation;
• the training and support of parents, particularly in behavioral techniques to use in the home.

There have been many studies on psychologically based early intervention programs; most of these are case studies of up to five participants. These studies typically examine non-core autistic problem behaviors such as self-injury, aggression, noncompliance, stereotypies and spontaneous language. Despite the widespread application of social skills training, its effectiveness is not firmly established. A randomized controlled study of a model for training parents in problem behaviors in their children with AS showed that parents attending a 1-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. 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.

No medications specifically target AS or directly treat the core symptoms of autism spectrum disorders; research into the efficacy of pharmaceutical intervention for AS is limited. However, it is essential to diagnose and treat comorbid conditions; medication can be effective in combination with behavioral interventions and environmental accommodations in treating comorbid symptoms such as anxiety, depression, inattention and aggression. The atypical neuroleptic medications risperidone and olanzapine have been shown to reduce the associated symptoms of AS; 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 repetitive behaviors and restricted interests.

Care must be taken in the management of pharmacotherapy; abnormalities in metabolism, cardiac conduction times, and an increased risk of type 2 diabetes have been raised as concerns with these medications and unintended side effects have largely been ignored in the literature. SSRIs can lead to manifestations of behavioral activation such as increased impulsivity, aggression and sleep disturbance. 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 and increased serum prolactin levels. Sedation and weight gain are more common with olanzapine, which has also been linked with diabetes. Sedative side-effects in school-age children 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.

Shift in view

Autistic people have contributed to 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 demand tolerance for what they call their neurodiversity. These views are the basis for the autistic rights and autistic pride movements.

Researcher Simon Baron-Cohen has argued that both AS and high-functioning autism are "differences" and not necessarily "disabilities." In proposing the more neutral term "difference", he suggests a subtle but important shift of emphasis to characterization of autism as a different cognitive style; this small shift in a term could mean the difference between a diagnosis of AS being received as a family tragedy, or as interesting information, such as learning that a child is left-handed. People with Asperger's, according to Baron-Cohen, "might not necessarily be disabled in an environment in which an exact mind, attracted to detecting small details, is an advantage". Attwood argues that "... the unusual profile of abilities that we define as Asperger's Syndrome has probably been an important and valuable characteristic of our species throughout evolution".

Prognosis

As of 2006, no studies addressing the long-term outcome of individuals with AS are available and there are no systematic long-term follow-up studies of children with AS. Individuals with AS appear to have normal life expectancy but have an increased prevalence of comorbid psychiatric conditions such as depression, mood disorders, and obsessive-compulsive disorder that may significantly affect prognosis. Although the social impairment is believed to be lifelong, outcome is generally more positive than with individuals with lower functioning autism spectrum disorders.

Children with AS are vulnerable to being teased and victimized; some may require special education services because of their social and behavioral difficulties although many attend regular education classes. Adolescents with AS may exhibit ongoing difficulty with self-care, organization and disturbances in social and romantic relationships; despite high cognitive potential, most remain at home, although some do marry and work independently. The "different-ness" adolescents experience can be traumatic. Although the deficits associated with AS are often debilitating, many individuals experience positive outcomes—particularly those who are able to excel in areas less dependent on social interaction, such as mathematics, music, and the sciences. Reports suggest that many people with AS are highly creative and accomplish innovative research in fields such as computer science, mathematics, and physics. Baron-Cohen reports a link between AS and high-achieving mathematicians, physicists and computer scientists that shows that the condition need not be an obstacle to achievement. The symptoms of AS can at some point "fade to normal" and people with AS can become valued workers as adults because of the "intensity of interest and volume of knowledge" that they may bring to idiosyncratic subjects, but they may lose employment if impaired understanding of social norms leads to poor judgment in work site behavior.

Education of families is critical in developing strategies for understanding strengths and weaknesses; prognosis is improved when individuals with AS have supportive families who are knowledgeable about Asperger's. Prognosis may be improved by diagnosis at a younger age that allows for early interventions, while interventions in adulthood are valuable but less beneficial. 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. The hypothesis that the combination of intact intellectual and linguistic ability with limited empathy and social understanding may predispose individuals with AS to violent or criminal behavior has been investigated and found to be unsupported by data.

Epidemiology

The incidence of AS is not well established, but conservative estimates using the DSM-IV criteria indicate that two to three of every 10,000 children have the condition, making it rarer than autistic disorder itself. A computerized registry in Denmark indicates an annual incidence of 1.4 per 10,000 for AS. Advocacy and parent support organizations have proliferated around the concept of AS, and there are indications that this has resulted in more frequent diagnoses of AS, which may be given as a "residual diagnosis" to children of normal intelligence who do not meet diagnostic criteria for autism but have some social difficulties.

A 2003 review of epidemiological studies found prevalence rates ranging from .03 to 4.8 per 1,000; the authors suggested a working rate of .26 per 1,000. A 1993 Sweden study found the prevalence of AS was 3.6 per 1,000 among school-aged children aged 7–16 using Gillberg's criteria, rising to 7.1 per 1,000 if suspected cases are included. The estimate is convincing for Sweden, but the findings may not apply elsewhere because they are based on a homogeneous population.

Prevalence estimates vary according to the diagnostic criteria employed. An epidemiological 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 and 1.6 for Szatmari et al. The number of children diagnosed as having AS according to any of the four criteria was 4.3 per 1,000. Leekam et al. documented significant differences between Gillberg's criteria and the ICD-10 criteria.

Like other autism spectrum disorders, AS prevalence estimates for males are higher than for females. The Sweden study found a 4:1 male to female ratio in subjects meeting Gillberg's criteria for AS, but a lower 2.3:1 ratio when suspected or borderline cases were included. The Finland study found a "somewhat surprising" male-to-female ratio according to DSM-IV criteria of 0.8:1; Gillberg and Gillberg criteria yielded a 2:1 ratio and the ratio when including children diagnosed per any of the four sets of diagnostic criteria was 1.7:1. Females with AS may not be recognized in studies as they tend to be superficially more sociable than boys, although closer examination reveals problems in social interaction.

Comorbidities

See also: Conditions comorbid to autism spectrum disorders

Most patients presenting in clinical settings with AS have other comorbid psychiatric disorders; children are likely to present with attention-deficit hyperactivity disorder (ADHD), while depression is a common diagnosis in adolescents and adults. Many children with AS are initially misdiagnosed with ADHD. Individuals with AS may also be diagnosed with oppositional defiant disorder, antisocial personality disorder, tic disorders and Tourette syndrome, general anxiety disorder, bipolar disorder, obsessive compulsive disorder or obsessive-compulsive personality disorder.

The conditions most commonly seen are depression and anxiety; comorbidity of these in persons with AS is estimated at 65%. Anxiety may stem from preoccupation over possible violations of routines and rituals or result from being placed in a situation without a clear schedule or expectations. Social anxiety (concern with failing in social encounters) may also manifest. Depression is often the result of chronic frustration from repeated failure to engage others socially, and mood disorders requiring treatment may develop.

The particularly high comorbidity with anxiety often requires special attention; one study reported that about 84% of individuals with a pervasive developmental disorder also met the criteria for anxiety disorder. Because of the social differences experienced by those with AS, such as trouble initiating or maintaining a conversation or adherence to strict rituals or schedules, additional stress to any of these activities may result in feelings of anxiety, which can negatively affect multiple areas of one's life, including school, family, and work. Anxiety disorders can be treated with medication or individual and group cognitive behavioral therapy, where relaxation or distraction-type activities may be used along with other techniques to diffuse the feelings of anxiety.

Psychosocial factors may contribute to poor adjustment or psychiatric issues. An Internet survey of middle-class mothers of children with AS and nonverbal learning disorders found peer and sibling victimization of the children was common; 94% of mothers reported peer victimization of their children. According to the mothers, in the year leading up to the study, almost three-quarters of the children had been hit by peers or siblings and 75% had been emotionally bullied. More seriously, 10% of the children were attacked by a gang and 15% were victims of nonsexual assaults to the genitals. Many of the children ate alone at lunch or were picked last for sports teams, and a third had not been invited to a birthday party in the past year.

Reports of high frequencies of medical anomalies common to AS and autism have not been replicated. 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. An increased rate of epilepsy is reported in individuals with AS, and there is a high rate (51%) of non-verbal learning disability.

History

Asperger syndrome is a relatively new diagnosis in the field of autism, named in honor of Hans Asperger (1906–80), an Austrian psychiatrist and pediatrician. An English psychiatrist, Lorna Wing popularized the term "Asperger's syndrome" in a 1981 publication; the first book in English on Asperger syndrome was written by Uta Frith in 1991 and the condition was subsequently recognized in formal diagnostic manuals later in the 1990s.

Asperger was the director of the University Children's Clinic in Vienna, spending most of his professional life in Vienna and publishing largely in German. In 1944, Asperger described in the paper " 'Autistic psychopathy' in childhood" four children in his practice who had difficulty in integrating themselves socially. Although their intelligence appeared normal, the children lacked nonverbal communication skills, failed to demonstrate empathy with their peers, and were physically clumsy. Their speaking was either disjointed or overly formal, and their all-absorbing interest in a single topic dominated their conversations. Asperger called the condition "autistic psychopathy" and described it as primarily marked by social isolation. Asperger called his young patients "little professors", and believed the individuals he described would be capable of exceptional achievement and original thought later in life.

Two subtypes of autism were described between 1943 and 1944 by two Austrian researchers working independently—Asperger and Austrian-born child psychiatrist Leo Kanner (1894–1981). Kanner immigrated to the United States in 1924; he described a similar syndrome in 1943, known as "classic autism" or "Kannerian autism", characterized by significant cognitive and communicative deficiencies, including delayed or absent language development. Kanner's descriptions were influenced by the developmental approach of Arnold Gesell, while Asperger was influenced by accounts of schizophrenia and personality disorders. Asperger's frame of reference was Eugen Bleuler's typology, which Gillberg described as "out of keeping with current diagnostic manuals", adding that Asperger's desriptions are "penetrating but not sufficiently systematic". Asperger was unaware of Kanner's description published a year before his; the two researchers were separated by an ocean and a raging war, and Asperger's descriptions were ignored in the United States. During his lifetime, Asperger's work, in German, remained largely unknown outside the German-speaking world.

According to Ishikawa and Ichihashi in the Japanese Journal of Clinical Medicine, the first author to use the term Asperger's syndrome in the English-language literature was the German physician, Gerhard Bosch. Between 1951 and 1962, Bosch worked as a psychiatrist at Frankfurt University. In 1962, he published a monograph detailing five case histories of individuals with PDD that was translated to English eight years later, becoming one of the first to establish German research on autism, and attracting attention outside the German-speaking world.

Lorna Wing is credited with widely popularizing the term "Asperger's syndrome" in the English-speaking medical community in her 1981 publication of a series of case studies of children showing similar symptoms. Wing also placed AS on the autism spectrum, although Asperger was uncomfortable characterizing his patient on the continuum of autistic spectrum disorders. She chose "Asperger's syndrome" as a neutral term to avoid the misunderstanding equated by the term autistic psychopathy with sociopathic behavior. Wing's translation and publication effectively introduced the diagnostic concept into American psychiatry and renamed the condition as Asperger's; however, her accounts blurred some of the distinctions between Asperger's and Kanner's descriptions because she included some mildly retarded children and some children who presented with language delays early in life.

The first systematic studies appeared in the late 1980s in publications by Tantam (1988) in the UK, Gillberg and Gilbert in Sweden (1989), and Szatmari, Bartolucci and Bremmer (1989) in North America. The diagnostic criteria for AS were outlined by Gillberg and Gillberg in 1989; Szatmari also proposed criteria in 1989. Asperger's work became more widely available in English when Uta Frith, an early researcher of Kannerian autism, translated his original paper in 1991. AS became a distinct diagnosis in 1992, when it was included in the 10th published 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 Diagnostic and statistical manual of mental disorders (DSM-IV) as Asperger's Disorder.

Less than two decades after the widespread introduction of AS to English-speaking audiences, there are hundreds of books, articles and websites describing it; prevalence figures have increased dramatically, with AS recognized as an important subgroup of the autism spectrum. However, questions remain concerning many aspects of AS; whether it should be a separate condition from high-functioning autism is a fundamental issue requiring further study. The diagnostic validity of Asperger syndrome is tentative, there is little consensus among clinical researchers about the usage of the term "Asperger's syndrome", and there are questions about the empirical validation of the DSM-IV and ICD-10 criteria. It is likely that the definition of the condition will change as new studies emerge and it will eventually be understood as a multifactorial heterogenous neurodevelopmental disorder involving a catalyst that results in prenatal or perinatal changes in brain structures.

Cultural aspects

See also: Autistic culture

People with AS may refer to themselves in casual conversation as "aspies", coined by Liane Holliday Willey in 1999, or as an "Aspergian". The term "neurotypical" (NT) describes a person whose neurological development and state are typical, and is often used to refer to people who are non-autistic.

A Wired magazine article, "The Geek Syndrome", suggested that AS is more common in Silicon Valley, a haven for computer scientists and mathematicians. It posited that AS may be the result of assortative mating by geeks in mathematical and technological areas. AS can be found in all occupations, however, and is not limited to those in the math and science fields.

The popularization of the Internet has allowed individuals with AS to communicate with each other in a way that was not previously possible due to the rarity and the geographic dispersal of individuals with AS. As a result of increasing ability to connect with one another, a subculture of "Aspies" has formed. Internet sites like Wrong Planet have made it easier for individuals to connect with each other.

See also

• Picture thinking
• Autistic Pride Day

External links

• Asperger's Syndrome at Curlie
• Asperger syndrome fact sheets - Fact sheets from autism-help.org for both parents of a child on the autistic spectrum and adults on the spectrum
• BBC's h2g2: "Autism and Asperger's Syndrome: The 'Little Professors'" (2006 April 19)
• CDC's "Learn the Signs. Act Early.” campaign - Information for parents on early childhood development and developmental disabilities
• Fresh Air with Terry Gross - National Public Radio (NPR) Program on Asperger's (2004 May 5)
• James I (2003). "Singular scientists". J R Soc Med. 96 (1): 36–9. PMID 12519805.
• MedlinePlus Asperger Syndrome Resources
• Radio Times with Marty Moss-Coane Real audio feed of hour long public radio segment on coping with Asperger's (2007 February 7)