Asperger syndrome — also referred to as Asperger's syndrome, Asperger's disorder, Asperger's, or just AS — is a pervasive developmental condition related to autism. It manifests to varying degrees with individual characteristics from case to case. It is classified as one of five neurobiological pervasive developmental disorders (PDD) and considered to be part of the autistic spectrum. It is typically characterized by problems with social skills and communication skills, but unlike autism, without delays in language or cognitive development.
Due to the mixed nature of the effects Asperger's Syndrome, its classification and diagnosis remain controversial among researchers, physicians, and those affected by it. It has been proposed to remove Asperger’s syndrome and 'pervasive developmental disorder not otherwise specified' from the Diagnostic and Statistical Manual of Mental Disorders V and include these two disorders into autism spectrum disorder.
Controverted classification: Asperger syndrome is not differentiated from other autistic spectrum disorders by a minority of clinicians. They refer to it in the research literature as high functioning autism (HFA)  in that early development is normal and there is no language delay and thus the symptoms differ only in degree from classic autism.
Learning disabilities: A large proportion of people diagnosed with AS do have learning disabilities, while tests of cognitive abilities may show normal or superior abilities in a portion of those who are diagnosed with it.
Issues in diagnosis: The diagnosis of AS is complicated by the lack of a standardized diagnostic instrument. Instead, numerous different instruments and diagnostic criteria are used. AS is often not identified in early childhood, and many individuals are not diagnosed until they are adults.
Intervention: Assistance for core symptoms of AS consists of therapies that apply behavior management strategies and address poor communication skills, obsessive or repetitive routines, and physical clumsiness. Many individuals with AS can adopt strategies for coping and do lead fulfilling lives - being gainfully employed, getting married or having successful relationships, and having families. In most cases, they are aware of their differences and can recognize if they need any support to maintain an independent life.
Asperger syndrome is named for Austrian psychiatrist and pediatrician Hans Asperger (1906-1980). In 1944, Asperger observed four children in his practice who had difficulty integrating socially. Although their intelligence appeared normal, the children lacked nonverbal communication skills, failed to demonstrate empathy with their peers, and were physically clumsy. Their way of speaking was either disjointed or overly formal, and their all-absorbing interest in a single topic dominated their conversations. Dr. Asperger called the condition “autistic psychopathy” and described it as a condition primarily marked by social isolation. He also stated that "exceptional human beings must be given exceptional educational treatment, treatment which takes into account their special difficulties. Further, we can show that despite abnormality, human beings can fulfill their social role within the community, especially if they find understanding, love and guidance".
The Austrian-American child psychiatrist Leo Kanner identified a very similar syndrome in 1943, although the population characterized by Kanner was perhaps less "socially functional" than Asperger's. Classic autism is therefore characterized by significant cognitive and communicative deficiencies, including delays in language development or complete lack of language. (In contrast, AS is characterized by normal language acquisition.)
Asperger’s observations were not widely known until 1981, when English psychologist Lorna Wing published a series of case studies of children showing similar symptoms, which she called "Asperger’s Syndrome". Wing’s writings were widely published and popularized. In 1992, the tenth published edition of the World Health Organization’s diagnostic manual and the International Classification of Diseases (ICD-10) included AS, making it a distinct diagnosis. In 1994, AS was recognized in the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) as Asperger's Disorder. 
Uta Frith (an early researcher of Kannerian autism) wrote that people with AS seem to have more than a touch of autism to them. Others, such as Lorna Wing and Tony Attwood, share Frith's assessment. Dr. Sally Ozonoff, of the University of California at Davis's MIND Institute, argues that there should be no dividing line 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 because they are identical in the way they need to be treated.
Classification and diagnosis
Note: The American Psychiatric Association, which publishes the Diagnostic and Statistical Manual of Mental Disorders, forbids the unauthorized reproduction of their diagnostic criteria. A narrative of the DSM-IV-TR criteria follows.
American Psychiatric Association
Asperger's Disorder (Asperger Syndrome) is defined in section 299.80 of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) by six main criteria:
- Quality of social interaction is markedly impaired;
- Behaviour and interests are demonstrably restricted, repetitive and stereotyped;
- Noticeable or measurable difficulties in functioning in other important areas;
- Language develops normally in that there is no significant delay in development;
- In infancy and early adolescence (up to three years of age), there must not be any demonstrable delay in intellectual development--curiosity, acquisition of skills in learning and independence, and behaviours that allow the child to adapt to different circumstances.
- The symptoms can not be explained better by symptomolgy of other specific pervasive developmental disorder or schizophrenia.
World Health Organization
The World Health Organization classification carries most of the same criteria as the APA's DSM-IV but also notes the disputed degree and substance of the symptomology.
Asperger's syndrome (F84.5)
This disorder is characterised by:
- social interaction disability of autistic type (see F84.0);
- restricted repetitive interests and activities (described in F84.0).
Asperger's syndrome is said by some authorities to differ from autism primarily in that there is no general delay or retardation in language or in cognitive development. However, the diagnosis is applicable to mentally retarded individuals who, while having no general retardation of language, do have highly deviant idiosyncratic or repetitive language.
Most affected individuals are markedly clumsy. The condition occurs predominantly in males (in a ratio of about 8 males to 1 female). The abnormalities persist into adolescence and adult life, and this is particularly characteristic of mentally retarded individuals affected by Asperger's syndrome. In some cases, often in individuals of borderline intelligence or with very mild degrees of mental retardation, psychotic episodes occasionally occur in early adult life.
Social interaction disability (F84.0 Childhood autism)
The basic disability is in the capacity to develop reciprocal social interaction, that is, a manner of behaviour which takes heed of, and responds to, the needs and behaviour of others. In mentally retarded subjects, this impairment commonly presents with:
- (i) lack of response to other people's emotions;
- (ii) deficient of inappropriate use of social signals.
Restricted repetitive behaviour (F84.0 Childhood autism)
An apparent preference for rigidity and routine in a wide range of aspects of daily living. There are many examples:
- (i) insistence to perform routines in nonfunctional rituals;
- (ii) motor stereotypies, especially in more severely retarded subjects;
- (iii) stereo typed interests, such as preoccupation with particular routes when travelling;
- (iv) resistance to change in personal environment (including moving of personal effects of furniture;
- (v) specific attachments to unusual, typically non-soft objects or interest in particular aspects of objects (such as smell or feel).
For any of these to be taken as an indicator of the presence of autism, it must be out of keeping with the general level of retardation. In more severely retarded individuals, only obvious and severe impairments of this type should be considered evidence of childhood autism.
All of these deficits may, in some individuals, occur as a result of general mental retardation. In assessing more severely retarded individuals, social interaction disability may be of more value in reaching the diagnosis of autism. As in the diagnosis of all developmental disorders in mentally retarded individuals, the coding should only be applied where the deficit is not simply due to the level of mental retardation. In addition to these specific diagnostic features, mentally retarded people with autism frequently show a variety of other non-specific problems such as self-injury (eg by headbanging or wrist biting), sleep disturbance, disturbances of eating behaviour (eg pica), temper tantrums and aggression. Most mentally retarded people who have autism lack spontaneity and initiative, and have difficulty applying themselves to any creative tasks (even when these are well within their general intellectual capacity). The manifestations of autism in any one individual change from childhood through to adulthood and into later adulthood, but a broadly persistent pattern is seen with continuity of deficits and socialisation, at any age, providing there is clear evidence of onset of the disorder within the first three years of life. 
Autism Spectrum Disorder
AS is classified as an autism spectrum disorder (ASD): AS is one of five neurological conditions characterized by difference in language and communication skills, as well as repetitive or restrictive patterns of thought and behavior. The four related disorders or conditions are Autism, Rett syndrome, childhood disintegrative disorder, and PDD-NOS (pervasive developmental disorder not otherwise specified).
The diagnosis of AS is complicated by the use of several different screening instruments. The diagnostic criteria of the Diagnostic and Statistical Manual are criticized for being vague and subjective. Other sets of diagnostic criteria for AS are the ICD 10, World Health Organization Diagnostic Criteria, Peter Szatmari Diagnostic Criteria, Christopher Gillberg's Criteria for Asperger's Disorder Diagnostic Criteria, and Attwood & Gray Discovery Criteria. The ICD-10 definition has similar criteria to the DSM-IV version. Asperger's syndrome had at different times been called Autistic psychopathy and "Schizoid personality disorder of childhood, although those terms are now understood as archaic and inaccurate, and are therefore no longer accepted in common use.
AS is also referred to in the literature as neither a separate or distinct disorder, referred to instead as high functioning autism (HFA). The diagnoses of AS or HFA are frequently used interchangeably in research literature, complicating prevalence estimates: the same child can receive different diagnoses, depending on the screening tool the doctor uses, and some children will be diagnosed with HFA instead of AS, and vice versa. Clinicians who do distinguish between HFA and As apply the early onset of High Functioning Autism or the regressive pattern of development as the distinguishing factor in differentiating between AS and HFA.
Greater precision to better differentiate between the various PDD diagnoses: The current classification of AS as a pervasive developmental disorders (PDDs) is disputed in that it may not reflect the true nature of the conditions. 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 rather than recognition of the conditions as distinct points on a spectrum, a strategy which has not been very useful in classification or in clinical practice.
- Narrow interests or preoccupation with a subject to the exclusion of other activities
- Repetitive behaviors or rituals
- Peculiarities in speech and language
- Extensive logical/technical patterns of thought
- Socially and emotionally inappropriate behavior and interpersonal interaction
- Problems with nonverbal communication
- Motor skills disorder: Clumsy and uncoordinated motor movements
The most common and important characteristics of AS can be divided into several broad categories: Social skills and social impairments, narrow but intense interests, and peculiarities of speech and language. Other features are commonly associated with this syndrome, but are not always regarded as necessary for diagnosis. This section mainly reflects the views of Attwood, Gillberg, and Wing on the most important characteristics of AS; the DSM-IV criteria represent a slightly different view. Unlike most forms of PDDs, AS is often camouflaged, and many people with the disorder blend in with those that do not have it. The effects of AS depend on how an affected individual responds to the syndrome itself.
Although there is no single feature that all people with AS share, difficulties with social behavior are nearly universal and are one of the most important defining criteria. Commonly, people with AS lack the natural ability to see the cultural nuances of social interaction and do not understand the unwritten rules of social behavior.They may lack the ability to communicate their own emotional state, resulting in well-meaning remarks that may offend, or finding it hard to know what is "acceptable".
One way to explain this inability to ascertain these social clues is labelled "mind-blindness". Mind-blindness (also known as a lack of "theory of mind") holds that people with AS can not learn social skills intuitively. By contrast, normally people are able to gather information about other people's cognitive and emotional states based on clues from the social environment, facial expressions and body language. To cope with the rules of socialisation, people with AS must learn these social skills intellectually through contrived, dry, math-like logic rather than intuitively through normal emotional interaction.
Without a theory of mind, it is reasoned, AS individuals lack the ability to recognize and understand the thoughts and feelings of others. Deprived of this insightful information, they are unable to interpret or understand the desires or intentions of others and thereby are unable to predict what to expect of others or what others may expect of them. This often leads to social awkwardness and inappropriate behavior.
- Difficulty reading the social and emotional messages in the eyes - People with AS don't look directly into another person's eyes, and when they do, they can't understand what they see.
- Making literal interpretation - AS individuals have trouble interpreting colloquialisms, sarcasm, and metaphors.
- Being considered disrespectful and rude - Prone to egocentric behavior, individuals with Asperger's miss cues and warning signs that their behavior is inappropriate.
- Honesty and deception - Children with Asperger's are often considered "too honest" and have difficulty being deceptive, even at the expense of hurting someone's feelings.
- Becoming aware of making social errors - As children with Asperger's mature, and become aware of their inability to connect, their fear of making a social mistake, and their self-criticism when they do so, can lead to a fear of interacting socially.
- A sense of paranoia - Because of their inability to develop rapport with others, persons with Asperger's have trouble distinguishing the difference between the deliberate or accidental actions of others, which can in turn lead to a feeling of paranoia.
- Managing conflict - Being unable to understand other points of view can lead to inflexibility and an inability to negotiate conflict resolution. Once the conflict is resolved, remorse may not be evident.
- Awareness of hurting the feelings of others - A lack of empathy often leads to unintentionally offensive or insensitive behaviors.
- Repairing someone's feelings - Lacking intuition about the feelings of others, people with AS have little understanding of how to console someone or how to make them feel better.
- Recognizing signs of boredom - Inability to understand other people's interests can lead AS persons to be inattentive to others. Conversely, people with AS often fail to notice when others are uninterested.
- Introspection and self-consciousness - Individuals with AS have difficulty understanding their own feelings or their impact on the feelings of other people.
- Clothing and personal hygiene - People with AS tend to be less affected by peer pressure than others. As a result, they often do what is comfortable and are unconcerned about their impact on others.
- Reciprocal love and grief - Since people with AS have difficulty emotionally, their expressions of affection and grief are often short and weak.
- Understanding of embarrassment and faux pas - Although persons with AS have an intellectual understanding of embarrassment and faux pas, they are unable to grasp concepts on an emotional level.
- Coping with criticism - People with AS are compelled to correct mistakes, even when they are made by someone in a position of authority, such as a teacher. For this reason, they can be unwittingly offensive.
- Speed and quality of social processing - Because they respond through reasoning and not intuition, AS individuals tend to process social information more slowly than the norm, leading to uncomfortable pauses or delays in response. This means that although the AS individual will tend to make a more reasoned and balanced understanding and/or decision, it can lead to the AS individual being told to use their 'common sense' to solve problems, a concept they cannot understand or use in the way a neurotypical person can.
- Exhaustion - As people with AS begin to understand theory of mind, they must make a deliberate effort to process social information. This often leads to mental exhaustion.
Given that a person with AS may have trouble understanding the emotions of other people, the messages that are conveyed by facial expression, eye contact and body language are often missed. They also might have trouble showing empathy with other people. Thus, people with AS might be seen as egotistical, selfish or uncaring. In most cases, these are unfair labels because affected people are emotionally unable to understand other people's emotional states. They are usually shocked, upset and remorseful when told that their actions are hurtful or inappropriate. It is clear that people with AS do not lack emotions. The concrete nature of emotional attachments they might have (i.e., to objects rather than to people), however, often seems curious or can even be a cause of concern to people who do not share their perspective.
The problem of understanding others may be exacerbated by the responses of people who interact with AS-affected persons. An Asperger patient's apparent emotional detachment may confuse and upset a typical person, who may in turn react illogically and emotionally — reactions that many Asperger patients find especially irritating. This can often become a vicious cycle and can sometimes cause families with Asperger-affected members to become especially dysfunctional.
Failing to show affection — or failing to do so in conventional ways — does not necessarily mean that people with AS do not feel affection. Understanding this can lead partners or care-givers to feel less rejected and to be more understanding. Increased understanding can also come from learning about AS and any comorbid disorders. Sometimes, the opposite problem occurs; a person with AS may be unusually affectionate to others or misinterprets signals, causing stress.
Another important aspect of the social differences often found in people with Asperger's is a lack of "central coherence", meaning that they may be so focused on details that they miss "the big picture". A person with a central coherence deficit might remember a story or an incident in great detail but be unable to make a statement about what the details mean, or they might understand a set of rules in detail but be unclear how or where they apply. That attention to details may be a seen as a bias rather than a deficit. There certainly appear to be many advantages to being detail oriented, particularly in activities and professions that require a high level of meticulousness. One also can see that this would cause problems if most non-autistic (but certainly not all) people are able to move fluidly between detail and big picture orientations.
Speech and language differences
People with AS typically have a highly pedantic way of speaking, using a far more formal language register than appropriate for a context. A five-year-old child with this condition may regularly speak in language that could easily have come from a university textbook, especially concerning his or her special area of interest.
Literal interpretation is another common, but not universal hallmark of this condition. Attwood gives the example of a girl with AS who answered the telephone one day and was asked, "Is Paul there?" Although the Paul in question was in the house, he was not in the room with her, so after looking around to ascertain this, she simply said "no" and hung up. The person on the other end had to call back and explain to her that he meant for her to find him and get him to pick up the telephone. A relatively famous example is that of physicist Richard Feynman who once recounted asking a librarian for a "map of the cat" when referring to an anatomical diagram.
Individuals with AS may use words idiosyncratically, including new neologisms (coinages) and unusual juxtapositions. This can develop into a rare gift for humor (especially puns, wordplay, doggerel and satire). A potential source of humor is the eventual realization that their literal interpretations can be used to amuse others. Some are so proficient at written language as to qualify as hyperlexic. Tony Attwood refers to a particular child's skill at inventing expressions, e.g., "tidying down" (the opposite of tidying up) or "broken" (when referring to a baby brother who cannot walk or talk).
Children with AS may show advanced abilities for their age in language, reading, mathematics, spatial skills, or music, sometimes into the 'gifted' range, but these talents may be counterbalanced by appreciable delays in the development of other cognitive functions. Some other typical behaviors are echolalia, the repetition or echoing of verbal utterances made by another person, and palilalia, the repetition of one's own words.
A study in 2003 investigated the written language of children and youth with AS. They were compared with non-AS children and youth of the same age in a standardized test of written language skills and legibility of handwriting. In written language skills, no significant differences were found between standardized scores of both groups; however, in hand-writing skills, the AS participants produced significantly fewer legible letters and words than the compared group. Another analysis of written samples of text, found that people with AS produce a similar quantity of text as their age group, but have difficulty in producing writing of quality.
A teacher may spend considerable time interpreting and correcting an AS child's indecipherable scrawl. When the child is also aware of the poor quality of his or her handwriting they may be reluctant to engage in activities that involve extensive writing. Unfortunately for some children and adults, high school teachers and prospective employers may consider the neatness of handwriting as a measure of intelligence and personality. The child may require assessment by an occupational therapist and remedial exercises, but current approaches can help minimize this problem. A parent or teacher aide could also act as the child's scribe or proofreader to ensure the legibility of the child's written answers or homework.
Narrow, intense interests
AS in children can involve an intense and obsessive level of focus on things of interest, many of which are those of ordinary children. The difference in children with AS is the unusual intensity of said interest. Some have suggested that these "obsessions" are essentially arbitrary and lacking in any real meaning or context; however, researchers note that these "obsessions" typically focus on the mechanical (how things work) as opposed to the psychological (how people work).
Sometimes these interests are lifelong; in other cases, they change at unpredictable intervals. In either case, there are normally one or two interests at any given time. In pursuit of these interests, people with AS often manifest extremely sophisticated reasoning, an almost obsessive focus, and a remarkably good memory for trivial facts (occasionally even eidetic memory). Hans Asperger called his young patients "little professors" because he thought his patients had as comprehensive and nuanced an understanding of their field of interest as university professors.
Some clinicians do not entirely agree with this description. For example, Wing and Gillberg both argue that, in children with AS, these areas of intense interest typically involve more rote memorization than real understanding, despite occasional appearances to the contrary. Such a limitation is an artifact of the diagnostic criteria, even under Gillberg's criteria, however.
People with AS may have little patience for things outside these narrow interests. In school, they may be perceived as highly intelligent underachievers or overachievers, clearly capable of outperforming their peers in their field of interest, yet persistently unmotivated to do regular homework assignments (sometimes even in their areas of interest). Others may be hypermotivated to outperform peers in school. The combination of social problems and intense interests can lead to unusual behavior, such as greeting a stranger by launching into a lengthy monologue about a special interest rather than introducing oneself in the socially accepted way. However, in many cases adults can outgrow this impatience and lack of motivation and develop more tolerance to new activities and meeting new people.
Those affected by AS may show a range of other sensory, developmental, and physiological anomalies. Children with AS may evidence a slight delay in the development of fine motor skills. In some cases, people with AS may have an odd way of walking, and may display compulsive finger, hand, arm or leg movements, including tics and stims.
In general, orderly things appeal to people with AS. Some researchers mention the imposition of rigid routines (on self or others) as a criterion for diagnosing this condition. It appears that changes to their routines cause inordinate levels of anxiety for some people with this condition.
Some people with AS experience varying degrees of sensory overload and are extremely sensitive to touch, smells, sounds, tastes, and sights. They may prefer soft clothing, familiar scents, or certain foods. Some may even be pathologically sensitive to loud noises (as some people with AS have hyperacusis), strong smells, or dislike being touched; for example, certain children with AS exhibit a strong dislike of having their head touched or their hair disturbed while others like to be touched but dislike loud noises. Sensory overload may exacerbate problems faced by such children at school, where levels of noise in the classroom can become intolerable for them. Some are unable to block out certain repetitive stimuli, such as the constant ticking of a clock. Whereas most children stop registering this sound after a short time and can hear it only if they consciously attend to it, a child with AS can become distracted, agitated, or even (in cases where the child has problems with regulating emotions such as anger) aggressive if the sound persists.
Strip-lighting, and computer monitors at low refresh rates (either of which may often be encountered in schools) can be very disturbing visual stimuli for AS people, contributing to otherwise inexplicable headaches, bad moods and agitation.
A study of parent measures of child temperament found that children with autism were rated as presenting with more extreme scores than typically-developing children.
Some research is to seek information about symptoms to aid in the diagnostic process. Other research is to identify a cause, although much of this research is still done on isolated symptoms. Many studies have exposed base differences in areas such as brain structure. To what end is currently unknown; research is ongoing, however.
Peter Szatmari suggests that AS was promoted as a diagnosis to spark more research into the syndrome: "It was introduced into the official classification systems in 1994 and has grown in popularity as a diagnosis, even though its validity has not been clearly established. It is interesting to note that it was introduced not so much as an indication of its status as a 'true' disorder, but more to stimulate research ... its validity is very much in question."
Research into causes
The direct cause(s) of AS is unknown. Even though no consensus exists for the cause(s) of AS, it is widely accepted that AS has a hereditary factor. It is suspected that multiple genes play a part in causing AS, since the number and severity of symptoms vary widely among individuals. Studies regarding the mirror neurons in the inferior parietal cortex have revealed differences which may underlie certain cognitive anomalies such as some of those which AS exhibits (e.g., understanding actions, learning through imitation, and the simulation of other people's behavior). Non-neurological factors such as poverty, lack of sleep, substance abuse by the mother during pregnancy, discrimination, trauma during early childhood, and abuse may also contribute.
Other possible causative mechanisms include a serotonin dysfunction and cerebellar dysfunction. Simon Baron-Cohen proposes a model for autism based on his empathising-systemising (E-S) theory. The E-S theory holds that the female brain is predominantly hard-wired for empathy, while the male brain is predominantly hard-wired for understanding and building systems, and that AS is an extreme of the male brain.
Some genetic studies point to involvement of neuroligins in AS. Neuroligins are a family of proteins thought to mediate cell-to-cell interactions between neurons. Neuroligins function as ligands for the neurexin family of cell surface receptors. Mutations in two X-linked genes encoding neuroligins NLGN3 and NLGN4 have been reported. These mutations affect cell-adhesion molecules localized at the synapse and suggest that a defect of synaptogenesis may predispose to autism.
There are other studies linking autism with differences in brain-volumes such as enlarged amygdala and hippocampus. Current research points to structural abnormalities in the brain as a cause of AS. These abnormalities impact neural circuits that control thought and behavior. Researchers suggest that gene/environment interactions cause some genes to turn on or turn off, or turn on too much or too little in the wrong places, and this interferes with the normal migration and wiring of embryonic brain cells during early development.
Other finds include brain region differences, such as decreased gray matter density in portions of the temporal cortex which are thought to play into the pathophysiology of ASDs (particularly in the integration of visual stimuli and affective information), and differing neural connectivity. Research on infants points to early differences in reflexes, which may be able to serve as an "early detector" of AS and autism.
Some professionals believe AS is not necessarily a disorder and thus should not be described in medical terms.
Treatment coordinates therapies that address the core symptoms of AS: poor communication skills, obsessive or repetitive routines, and physical clumsiness. AS and high-functioning autism may be considered together for the purpose of clinical management.
A typical treatment program generally includes:
- social skills training, to teach the skills to more successfully interact with others;
- cognitive behavioral therapy, to help in better managing emotions that may be explosive or anxious, and to cut back on obsessive interests and repetitive routines;
- medication, for co-existing conditions such as depression, anxiety, and ADD/ADHD;
- occupational or physical therapy, to assist with sensory integration problems or poor motor coordination;
- specialized speech therapy, to help with the trouble of the "give and take" in normal conversation;
- parent training and support, to teach parents behavioral techniques to use at home; and,
- counseling to support individuals with AS to increase self-awareness skills and to help them develop and manage the emotions around social experiences.
The techniques described above will not cure AS, but help those diagnosed with AS better function in society.
Children with AS can learn to manage their differences, but they may continue to find social situations and personal relationships challenging. Adults with AS are able to work successfully in mainstream jobs and live an independent life.
Individuals with AS may make great intellectual contributions: published case reports suggest an association with accomplishments in engineering, computer science, mathematics, and physics. The deficits associated with AS may be debilitating, but 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.
The prevalence 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. Three to four times as many boys have AS compared with girls. The universality of AS across races, and validity of epidemiologic studies to date, is questioned.
A 1993 cross-section study in Sweden found that 36 per 10,000 school-aged children met Gillberg's criteria for AS, rising to 71 per 10,000 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. The Sweden study demonstrated that AS may be more common than once thought and may be currently underdiagnosed. Gillberg estimates 30-50% of all persons with AS are undiagnosed. A survey found that 36 per 10,000 adults with an IQ of 100 or above may meet criteria for AS.
Leekam et al. documented significant differences between Gillberg's criteria and the ICD-10 criteria. Considering its requirement for "normal" development of cognitive skills, language, curiosity and self-help skills, the ICD-10 definition is considerably more narrow than Gillberg's criteria, which more closely matches Hans Asperger's own descriptions.
Like other autism spectrum disorders, AS prevalence estimates for males are higher than for females, but some clinicians believe that this may not reflect the actual incidence rates. Tony Attwood suggests that females learn to compensate better for their impairments due to gender differences in the handling of socialization. The Ehlers & Gillberg 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 prevalence of AS in adults is not well understood, but Baron-Cohen et al. documented that 2% of adults score higher than 32 in his Autism Spectrum Quotient (AQ) questionnaire, developed in 2001 to measure the extent to which an adult of normal intelligence has the traits associated with autism spectrum conditions. All interviewed high-scorers met at least 3 DSM-IV criteria, and 63% met threshold criteria for an ASD diagnosis; a Japanese study found similar AQ Test results.
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. A study of referred adult patients found that 30% presenting with ADHD had ASD as well.
Research indicates people with AS may be far more likely to have the associated conditions. People with AS symptoms may frequently be diagnosed with clinical depression, oppositional defiant disorder, antisocial personality disorder, Tourette syndrome, ADHD, general anxiety disorder, bipolar disorder, obsessive compulsive disorder or obsessive-compulsive personality disorder. Dysgraphia, dyspraxia, dyslexia or dyscalculia may also be diagnosed.
The particularly high comorbidity with anxiety often requires special attention. One study reported that about 84 percent of individuals with a Pervasive Developmental Disorder (PDD) also met the criteria to be diagnosed with an 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. Treatment of anxiety disorders that accompany a PDD can be handled in a number of ways, such as through medication or individual and group cognitive behavioral therapy, where relaxation or distraction-type activities may be used along with other techniques in order to diffuse the feelings of anxiety.
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