|Classification and external resources|
People with Asperger syndrome often display intense interests, such as this boy's fascination with molecular structure.
|Patient UK||Asperger syndrome|
Asperger syndrome (AS), also known as Asperger disorder (AD) or simply Asperger's, is an autism spectrum disorder (ASD) that is characterized by significant difficulties in social interaction and nonverbal communication, alongside restricted and repetitive patterns of behavior and interests. It differs from other autism spectrum disorders by its relative preservation of linguistic and cognitive development. Although not required for diagnosis, physical clumsiness and atypical (peculiar or odd) use of language are frequently reported. The diagnosis of Asperger's was eliminated in the 2013 fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and replaced by a diagnosis of autism spectrum disorder on a severity scale.
The syndrome is named after the Austrian pediatrician Hans Asperger who, in 1944, studied and described children in his practice who lacked nonverbal communication skills, demonstrated limited empathy with their peers, and were physically clumsy. The modern conception of Asperger syndrome came into existence in 1981 and went through a period of popularization, becoming standardized as a diagnosis in the early 1990s. Many questions and controversies remain about aspects of the disorder. There is doubt about whether it is distinct from high-functioning autism (HFA); partly because of this, its prevalence is not firmly established.
The exact cause of Asperger's is unknown. Although research suggests the likelihood of a genetic basis, there is no known genetic cause and brain imaging techniques have not identified a clear common pathology. There is no single treatment, and the effectiveness of particular interventions is supported by only limited data. Intervention is aimed at improving symptoms and function. The mainstay of management is behavioral therapy, focusing on specific deficits to address poor communication skills, obsessive or repetitive routines, and physical clumsiness. Most children improve as they mature to adulthood, but social and communication difficulties may persist. Some researchers and people with Asperger's have advocated a shift in attitudes toward the view that it is a difference, rather than a disability that must be treated or cured.
- 1 Classification
- 2 Characteristics
- 3 Causes
- 4 Mechanism
- 5 Diagnosis
- 6 Screening
- 7 Management
- 8 Prognosis
- 9 Epidemiology
- 10 History
- 11 Society and culture
- 12 References
- 13 External links
The extent of the overlap between AS and high-functioning autism (HFA—autism unaccompanied by intellectual disability) is unclear. The ASD classification is to some extent an artifact of how autism was discovered, and may not reflect the true nature of the spectrum; methodological problems have beset Asperger syndrome as a valid diagnosis from the outset. In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published in May 2013, AS, as a separate diagnosis, was eliminated and folded into autism spectrum disorder. Like the diagnosis of Asperger syndrome, the change was controversial and AS was not removed from the WHO's ICD-10.
The World Health Organization (WHO) defines Asperger syndrome (AS) as one of the autism spectrum disorders (ASD) or pervasive developmental disorders (PDD), which are a spectrum of psychological conditions that are characterized by abnormalities of social interaction and communication that pervade the individual's functioning, and by restricted and repetitive interests and behavior. Like other psychological development disorders, ASD begins in infancy or childhood, has a steady course without remission or relapse, and has impairments that result from maturation-related changes in various systems of the brain. ASD, in turn, is a subset of the broader autism phenotype, which describes individuals who may not have ASD but do have autistic-like traits, such as social deficits. Of the other four ASD forms, autism is the most similar to AS in signs and likely causes, but its diagnosis requires impaired communication and allows delay in cognitive development; Rett syndrome and childhood disintegrative disorder share several signs with autism but may have unrelated causes; and pervasive developmental disorder not otherwise specified (PDD-NOS) is diagnosed when the criteria for a more specific disorder are unmet.
As a pervasive developmental disorder, Asperger syndrome is distinguished by a pattern of symptoms rather than a single symptom. It is characterized by qualitative impairment in social interaction, by stereotyped and restricted patterns of behavior, activities and interests, and by no clinically significant delay in cognitive development or general delay in language. Intense preoccupation with a narrow subject, one-sided verbosity, restricted prosody, and physical clumsiness are typical of the condition, but are not required for diagnosis.
A lack of demonstrated empathy has a significant impact on aspects of communal living for persons with Asperger syndrome. Individuals with AS experience difficulties in basic elements of social interaction, which may include a failure to develop friendships or to seek shared enjoyments or achievements with others (for example, showing others objects of interest), a lack of social or emotional reciprocity (social "games" give-and-take mechanic), and impaired nonverbal behaviors in areas such as eye contact, facial expression, posture, and gesture.
People with AS may not be as withdrawn around others compared to those with other, more debilitating forms of autism; they approach others, even if awkwardly. For example, a person with AS may engage in a one-sided, long-winded speech about a favorite topic, while misunderstanding or not recognizing the listener's feelings or reactions, such as a wish to change the topic of talk or end the interaction. This social awkwardness has been called "active but odd". This failure to react appropriately to social interaction may appear as disregard for other people's feelings, and may come across as insensitive. However, not all individuals with AS will approach others. Some of them may even display selective mutism, speaking not at all to most people and excessively to specific people. Some may choose only to talk to people they like.
The cognitive ability of children with AS often allows them to articulate social norms in a laboratory context, where they may be able to show a theoretical understanding of other people's emotions; however, they typically have difficulty acting on this knowledge in fluid, real-life situations. People with AS may analyze and distill their observations of social interaction into rigid behavioral guidelines, and apply these rules in awkward ways, such as forced eye contact, resulting in a demeanor that appears rigid or socially naive. Childhood desire for companionship can become numbed through a history of failed social encounters.
The hypothesis that individuals with AS are predisposed to violent or criminal behavior has been investigated, but is not supported by data. More evidence suggests children with AS are victims rather than victimizers. A 2008 review found that an overwhelming number of reported violent criminals with AS had coexisting psychiatric disorders such as schizoaffective disorder.
Restricted and repetitive interests and behavior
People with Asperger syndrome display behavior, interests, and activities that are restricted and repetitive and are sometimes abnormally intense or focused. They may stick to inflexible routines, move in stereotyped and repetitive ways, or preoccupy themselves with parts of objects.
Pursuit of specific and narrow areas of interest is one of the most striking features of AS. Individuals with AS may collect volumes of detailed information on a relatively narrow topic such as weather data or star names, without necessarily having a genuine understanding of the broader topic. For example, a child might memorize camera model numbers while caring little about photography. This behavior is usually apparent by age 5 or 6. Although these special interests may change from time to time, they typically become more unusual and narrowly focused, and often dominate social interaction so much that the entire family may become immersed. Because narrow topics often capture the interest of children, this symptom may go unrecognized.
Stereotyped and repetitive motor behaviors are a core part of the diagnosis of AS and other ASDs. They include hand movements such as flapping or twisting, and complex whole-body movements. These are typically repeated in longer bursts and look more voluntary or ritualistic than tics, which are usually faster, less rhythmical and less often symmetrical.
According to the Adult Asperger Assessment (AAA) diagnostic test, a lack of interest in fiction and a positive preference towards non-fiction is common among adults with AS.
Speech and language
Although individuals with Asperger syndrome acquire language skills without significant general delay and their speech typically lacks significant abnormalities, language acquisition and use is often atypical. Abnormalities include verbosity, abrupt transitions, literal interpretations and miscomprehension of nuance, use of metaphor meaningful only to the speaker, auditory perception deficits, unusually pedantic, formal or idiosyncratic speech, and oddities in loudness, pitch, intonation, prosody, and rhythm. Echolalia has also been observed in individuals with AS.
Three aspects of communication patterns are of clinical interest: poor prosody, tangential and circumstantial speech, and marked verbosity. Although inflection and intonation may be less rigid or monotonic than in classic autism, people with AS often have a limited range of intonation: speech may be unusually fast, jerky or loud. Speech may convey a sense of incoherence; the conversational style often includes monologues about topics that bore the listener, fails to provide context for comments, or fails to suppress internal thoughts. Individuals with AS may fail to detect whether the listener is interested or engaged in the conversation. The speaker's conclusion or point may never be made, and attempts by the listener to elaborate on the speech's content or logic, or to shift to related topics, are often unsuccessful.
Children with AS may have an unusually sophisticated vocabulary at a young age and have been colloquially called "little professors", but have difficulty understanding figurative language and tend to use language literally. Children with AS appear to have particular weaknesses in areas of nonliteral language that include humor, irony, teasing, and sarcasm. Although individuals with AS usually understand the cognitive basis of humor, they seem to lack understanding of the intent of humor to share enjoyment with others. Despite strong evidence of impaired humor appreciation, anecdotal reports of humor in individuals with AS seem to challenge some psychological theories of AS and autism.
Motor and sensory perception
Individuals with Asperger syndrome may have signs or symptoms that are independent of the diagnosis, but can affect the individual or the family. These include differences in perception and problems with motor skills, sleep, and emotions.
Individuals with AS often have excellent auditory and visual perception. Children with ASD often demonstrate enhanced perception of small changes in patterns such as arrangements of objects or well-known images; typically this is domain-specific and involves processing of fine-grained features. Conversely, compared to individuals with high-functioning autism, individuals with AS have deficits in some tasks involving visual-spatial perception, auditory perception, or visual memory. Many accounts of individuals with AS and ASD report other unusual sensory and perceptual skills and experiences. They may be unusually sensitive or insensitive to sound, light, and other stimuli; these sensory responses are found in other developmental disorders and are not specific to AS or to ASD. There is little support for increased fight-or-flight response or failure of habituation in autism; there is more evidence of decreased responsiveness to sensory stimuli, although several studies show no differences.
Hans Asperger's initial accounts and other diagnostic schemes include descriptions of physical clumsiness. Children with AS may be delayed in acquiring skills requiring motor dexterity, such as riding a bicycle or opening a jar, and may seem to move awkwardly or feel "uncomfortable in their own skin". They may be poorly coordinated, or have an odd or bouncy gait or posture, poor handwriting, or problems with visual-motor integration. They may show problems with proprioception (sensation of body position) on measures of developmental coordination disorder (motor planning disorder), balance, tandem gait, and finger-thumb apposition. There is no evidence that these motor skills problems differentiate AS from other high-functioning ASDs.
Children with AS are more likely to have sleep problems, including difficulty in falling asleep, frequent nocturnal awakenings, and early morning awakenings. AS is also associated with high levels of alexithymia, which is difficulty in identifying and describing one's emotions. Although AS, lower sleep quality, and alexithymia are associated, their causal relationship is unclear.
Hans Asperger described common symptoms among his patients' family members, especially fathers, and research supports this observation and suggests a genetic contribution to Asperger syndrome. Although no specific gene has yet been identified, multiple factors are believed to play a role in the expression of autism, given the phenotypic variability seen in children with AS. 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.
A few ASD cases have been linked to exposure to teratogens (agents that cause birth defects) during the first eight weeks from conception. Although this does not exclude the possibility that ASD can be initiated or affected later, it is strong evidence that it arises very early in development. Many environmental factors have been hypothesized to act after birth, but none has been confirmed by scientific investigation.
Asperger syndrome appears to result from developmental factors that affect many or all functional brain systems, as opposed to localized effects. Although the specific underpinnings of AS or factors that distinguish it from other ASDs are unknown, and no clear pathology common to individuals with AS has emerged, it is still possible that AS's mechanism is separate from other ASDs. Neuroanatomical studies and the associations with teratogens strongly suggest that the mechanism includes alteration of brain development soon after conception. Abnormal migration of embryonic cells during fetal development may affect the final structure and connectivity of the brain, resulting in alterations in the neural circuits that control thought and behavior. Several theories of mechanism are available; none are likely to provide a complete explanation.
The underconnectivity theory hypothesizes underfunctioning high-level neural connections and synchronization, along with an excess of low-level processes. It maps well to general-processing theories such as weak central coherence theory, which hypothesizes that a limited ability to see the big picture underlies the central disturbance in ASD. A related theory—enhanced perceptual functioning—focuses more on the superiority of locally oriented and perceptual operations in autistic individuals.
The mirror neuron system (MNS) theory hypothesizes that alterations to the development of the MNS interfere with imitation and lead to Asperger's core feature of social impairment. For example, one study found that activation is delayed in the core circuit for imitation in individuals with AS. This theory maps well to social cognition theories like the theory of mind, which hypothesizes that autistic behavior arises from impairments in ascribing mental states to oneself and others, or hyper-systemizing, which hypothesizes that autistic individuals can systematize internal operation to handle internal events but are less effective at empathizing by handling events generated by other agents.
Standard diagnostic criteria require impairment in social interaction and repetitive and stereotyped patterns of behavior, activities and interests, without significant delay in language or cognitive development. Unlike the international standard, the DSM-IV-TR criteria also required significant impairment in day-to-day functioning; DSM-5 eliminated AS as a separate diagnosis in 2013, and folded it into the umbrella of autism spectrum disorders. Other sets of diagnostic criteria have been proposed by Szatmari et al. and by Gillberg and Gillberg.
Diagnosis is most commonly made between the ages of four and eleven. A comprehensive assessment involves a multidisciplinary team that observes across multiple settings, and includes neurological and genetic assessment as well as tests for cognition, psychomotor function, verbal and nonverbal strengths and weaknesses, style of learning, and skills for independent living. The "gold standard" in diagnosing ASDs combines clinical judgment with the Autism Diagnostic Interview-Revised (ADI-R)—a semistructured parent interview—and the Autism Diagnostic Observation Schedule (ADOS)—a conversation and play-based interview with the child. Delayed or mistaken diagnosis can be traumatic for individuals and families; for example, misdiagnosis can lead to medications that worsen behavior. Many children with AS are initially misdiagnosed with attention deficit hyperactivity disorder (ADHD). Diagnosing adults is more challenging, as standard diagnostic criteria are designed for children and the expression of AS changes with age; adult diagnosis requires painstaking clinical examination and thorough medical history gained from both the individual and other people who know the person, focusing on childhood behavior. Conditions that must be considered in a differential diagnosis include other ASDs, the schizophrenia spectrum, ADHD, obsessive–compulsive disorder, major depressive disorder, semantic pragmatic disorder, nonverbal learning disorder, Tourette syndrome, stereotypic movement disorder, bipolar disorder,  and social-cognitive deficits due to brain damage from alcohol abuse.
Underdiagnosis and overdiagnosis are problems in marginal cases. The cost and difficulty of screening and assessment can delay diagnosis. Conversely, the increasing popularity of drug treatment options and the expansion of benefits has motivated providers to overdiagnose ASD. There are indications AS has been diagnosed more frequently in recent years, partly as a residual diagnosis for children of normal intelligence who are not autistic but have social difficulties.
There are questions about the external validity of the AS diagnosis. That is, it is unclear whether there is a practical benefit in distinguishing AS from HFA and from PDD-NOS; the same child can receive different diagnoses depending on the screening tool. The debate about distinguishing AS from HFA is partly due to a tautological dilemma where disorders are defined based on severity of impairment, so that studies that appear to confirm differences based on severity are to be expected.
Parents of children with Asperger syndrome can typically trace differences in their children's development to as early as 30 months of age. Developmental screening during a routine check-up by a general practitioner or pediatrician may identify signs that warrant further investigation. The diagnosis of AS is complicated by the use of several different screening instruments, including the Asperger Syndrome Diagnostic Scale (ASDS), Autism Spectrum Screening Questionnaire (ASSQ), Childhood Autism Spectrum Test (CAST) (previously called the Childhood Asperger Syndrome Test), Gilliam Asperger's Disorder Scale (GADS), Krug Asperger's Disorder Index (KADI), and the Autism Spectrum Quotient (AQ; with versions for children, adolescents and adults). None have been shown to reliably differentiate between AS and other ASDs.
Asperger syndrome treatment attempts to manage distressing symptoms and to teach age-appropriate social, communication and vocational skills that are not naturally acquired during development, with intervention tailored to the needs of the individual 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 core symptoms of the disorder, including poor communication skills and obsessive or repetitive routines. While most professionals agree that the earlier the intervention, the better, there is no single best treatment package. 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 program generally includes:
- An applied behavior analysis (ABA) technique called social skills training for more effective interpersonal interactions;
- Cognitive behavioral therapy to improve stress management relating to anxiety or explosive emotions and to cut back on obsessive interests and repetitive routines;
- Medication, for coexisting conditions such as major depressive disorder and anxiety disorder;
- Occupational or physical therapy to assist with poor sensory processing and motor coordination;
- Social communication intervention, which is specialized speech therapy to help with the pragmatics of the give and take of normal conversation;
- An ABA procedure known as positive behavior support includes training and support of parents and school faculty in behavior management strategies to use in the home and school.
Of the many studies on behavior-based early intervention programs, most are case reports of up to five participants and typically examine a few problem behaviors such as self-injury, aggression, noncompliance, stereotypies, or spontaneous language; unintended side effects are largely ignored. Despite the popularity 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 one-day workshop or six individual lessons reported fewer behavioral problems, while parents receiving the individual lessons reported less intense behavioral problems in their AS children. 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 can improve the work and life management of people with AS.
No medications directly treat the core symptoms of AS. Although research into the efficacy of pharmaceutical intervention for AS is limited, it is essential to diagnose and treat comorbid conditions. Deficits in self-identifying emotions or in observing effects of one's behavior on others can make it difficult for individuals with AS to see why medication may be appropriate. Medication can be effective in combination with behavioral interventions and environmental accommodations in treating comorbid symptoms such as anxiety disorder, major depressive disorder, inattention and aggression. The atypical antipsychotic 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 restricted and repetitive interests and behaviors.
Care must be taken with medications, as side effects may be more common and harder to evaluate in individuals with AS, and tests of drugs' effectiveness against comorbid conditions routinely exclude individuals from the autism spectrum. Abnormalities in metabolism, cardiac conduction times, and an increased risk of type 2 diabetes have been raised as concerns with these medications, along with serious long-term neurological side effects. 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.
There is some evidence that children with AS may see a lessening of symptoms; up to 20% of children may no longer meet the diagnostic criteria as adults, although social and communication difficulties may persist. As of 2006, no studies addressing the long-term outcome of individuals with Asperger syndrome are available and there are no systematic long-term follow-up studies of children with AS. Individuals with AS appear to have normal life expectancy, but have an increased prevalence of comorbid psychiatric conditions, such as major depressive disorder and anxiety disorder that may significantly affect prognosis. Although social impairment is lifelong, the outcome is generally more positive than with individuals with lower functioning autism spectrum disorders; for example, ASD symptoms are more likely to diminish with time in children with AS or HFA. Although most students with AS/HFA have average mathematical ability and test slightly worse in mathematics than in general intelligence, some are gifted in mathematics and AS has not prevented some adults from major accomplishments such as Vernon L. Smith winning the Nobel Prize.
Although many attend regular education classes, some children with AS may utilize special education services because of their social and behavioral difficulties. Adolescents with AS may exhibit ongoing difficulty with self care or organization, and disturbances in social and romantic relationships. Despite high cognitive potential, most young adults with AS remain at home, although some do marry and work independently. The "different-ness" adolescents experience can be traumatic. Anxiety may stem from preoccupation over possible violations of routines and rituals, from being placed in a situation without a clear schedule or expectations, or from concern with failing in social encounters; the resulting stress may manifest as inattention, withdrawal, reliance on obsessions, hyperactivity, or aggressive or oppositional behavior. Depression is often the result of chronic frustration from repeated failure to engage others socially, and mood disorders requiring treatment may develop. Clinical experience suggests the rate of suicide may be higher among those with AS, but this has not been confirmed by systematic empirical studies.
Education of families is critical in developing strategies for understanding strengths and weaknesses; helping the family to cope improves outcomes in children. 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.
Prevalence estimates vary enormously. A 2003 review of epidemiological studies of children found autism prevalence rates ranging from 0.03 to 4.84 per 1,000, with the ratio of autism to Asperger syndrome ranging from 1.5:1 to 16:1; combining the geometric mean ratio of 5:1 with a conservative prevalence estimate for autism of 1.3 per 1,000 suggests indirectly that the prevalence of AS might be around 0.26 per 1,000. Part of the variance in estimates arises from differences in diagnostic criteria. For example, a relatively small 2007 study of 5,484 eight-year-old children in Finland found 2.9 children per 1,000 met the ICD-10 criteria for an AS diagnosis, 2.7 per 1,000 for Gillberg and Gillberg criteria, 2.5 for DSM-IV, 1.6 for Szatmari et al., and 4.3 per 1,000 for the union of the four criteria. Boys seem to be more likely to have AS than girls; estimates of the sex ratio range from 1.6:1 to 4:1, using the Gillberg and Gillberg criteria.
Anxiety disorder and major depressive disorder are the most common conditions seen at the same time; comorbidity of these in persons with AS is estimated at 65%. 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. One study of males with AS found an increased rate of epilepsy and a high rate (51%) of nonverbal learning disorder. AS is associated with tics, Tourette syndrome, and bipolar disorder, and the repetitive behaviors of AS have many similarities with the symptoms of obsessive–compulsive disorder and obsessive–compulsive personality disorder. However many of these studies are based on clinical samples or lack standardized measures; nonetheless, comorbid conditions are relatively common.
Named after the Austrian pediatrician Hans Asperger (1906–1980), Asperger syndrome is a relatively new diagnosis in the field of autism. As a child, Asperger appears to have exhibited some features of the very condition named after him, such as remoteness and talent in language. In 1944, Asperger described four children in his practice who had difficulty in integrating themselves socially. The children lacked nonverbal communication skills, failed to demonstrate empathy with their peers, and were physically clumsy. Asperger called the condition "autistic psychopathy" and described it as primarily marked by social isolation. Fifty years later, several standardizations of AS as a diagnosis were tentatively proposed, many of which diverge significantly from Asperger's original work.
Unlike today's AS, autistic psychopathy could be found in people of all levels of intelligence, including those with intellectual disability. In the context of the Nazi eugenics policy of sterilizing and killing social deviants and the mentally handicapped, Asperger passionately defended the value of autistic individuals, writing "We are convinced, then, that autistic people have their place in the organism of the social community. They fulfill their role well, perhaps better than anyone else could, and we are talking of people who as children had the greatest difficulties and caused untold worries to their care-givers." Asperger also called his young patients "little professors", and believed some would be capable of exceptional achievement and original thought later in life. His paper was published during wartime and in German, so it was not widely read elsewhere.
Lorna Wing popularized the term Asperger syndrome in the English-speaking medical community in her 1981 publication of a series of case studies of children showing similar symptoms, and Uta Frith translated Asperger's paper to English in 1991. Sets of diagnostic criteria were outlined by Gillberg and Gillberg in 1989 and by Szatmari et al. in the same year. AS became a standard diagnosis in 1992, when it was included in the tenth edition of the World Health Organization's diagnostic manual, International Classification of Diseases (ICD-10); in 1994, it was added to the fourth edition of the American Psychiatric Association's diagnostic reference, Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).
Hundreds of books, articles and websites now describe AS, and prevalence estimates have increased dramatically for ASD, with AS recognized as an important subgroup. Whether it should be seen as distinct from high-functioning autism is a fundamental issue requiring further study, and there are questions about the empirical validation of the DSM-IV and ICD-10 criteria. In 2013, DSM-5 eliminated AS as a separate diagnosis, folding it into the autism spectrum on a severity scale.
Society and culture
People identifying with Asperger syndrome may refer to themselves in casual conversation as aspies (a term first used in print by Liane Holliday Willey in 1999). The word neurotypical (abbreviated NT) describes a person whose neurological development and state are typical, and is often used to refer to non-autistic people. The Internet has allowed individuals with AS to communicate and celebrate diversity with each other in a way that was not previously possible because of their rarity and geographic dispersal. A subculture of aspies has formed. Internet sites like Wrong Planet have made it easier for individuals to connect.
Autistic people have advocated a shift in perception of autism spectrum disorders as complex syndromes rather than diseases that must be cured. Proponents of this view reject the notion that there is an "ideal" brain configuration and that any deviation from the norm is pathological; they promote tolerance for what they call neurodiversity. These views are the basis for the autistic rights and autistic pride movements. There is a contrast between the attitude of adults with self-identified AS, who typically do not want to be cured and are proud of their identity, and parents of children with AS, who typically seek assistance and a cure for their children.
Some researchers have argued that AS can be viewed as a different cognitive style, not a disorder or a disability, and that it should be removed from the standard Diagnostic and Statistical Manual, much as homosexuality was removed. In a 2002 paper, Simon Baron-Cohen wrote of those with AS, "In the social world, there is no great benefit to a precise eye for detail, but in the worlds of maths, computing, cataloging, music, linguistics, engineering, and science, such an eye for detail can lead to success rather than failure." Baron-Cohen cited two reasons why it might still be useful to consider AS to be a disability: to ensure provision for legally required special support, and to recognize emotional difficulties from reduced empathy. Baron-Cohen argues that the genes for Asperger's combination of abilities have operated throughout recent human evolution and have made remarkable contributions to human history.
- McPartland J, Klin A (2006). "Asperger's syndrome". Adolesc Med Clin 17 (3): 771–88. doi:10.1016/j.admecli.2006.06.010. PMID 17030291.
- Baskin JH, Sperber M, Price BH (2006). "Asperger syndrome revisited". Rev Neurol Dis 3 (1): 1–7. PMID 16596080.
- "299.80 Asperger's Disorder". DSM-5 Development. American Psychiatric Association. Archived from the original on 25 December 2010. Retrieved 21 December 2010.
- Asperger H; tr. and annot. Frith U (1991) . "'Autistic psychopathy' in childhood". In Frith U. Autism and Asperger syndrome. Cambridge University Press. pp. 37–92. ISBN 0-521-38608-X.
- Klin A, Pauls D, Schultz R, Volkmar F (2005). "Three diagnostic approaches to Asperger syndrome: Implications for research". J of Autism and Dev Dis 35 (2): 221–34. doi:10.1007/s10803-004-2001-y. PMID 15909408.
- Wing L (1998). "The history of Asperger syndrome". In Schopler E, Mesibov GB, Kunce LJ. Asperger syndrome or high-functioning autism?. New York: Plenum press. pp. 11–25. ISBN 0-306-45746-6.
- Woodbury-Smith M, Klin A, Volkmar F (2005). "Asperger's Syndrome: A Comparison of Clinical Diagnoses and Those Made According to the ICD-10 and DSM-IV". J of Autism and Dev Disord. 35 (2): 235–240. doi:10.1007/s10803-004-2002-x. PMID 15909409.
- Woodbury-Smith MR, Volkmar FR (January 2009). "Asperger syndrome". Eur Child Adolesc Psychiatry 18 (1): 2–11. doi:10.1007/s00787-008-0701-0. PMID 18563474.
- Klin A (2006). "Autism and Asperger syndrome: an overview". Rev Bras Psiquiatr 28 (suppl 1): S3–S11. doi:10.1590/S1516-44462006000500002. PMID 16791390.
- Matson JL, Minshawi NF (2006). "Etiology and prevalence". Early intervention for autism spectrum disorders: a critical analysis. Amsterdam: Elsevier Science. p. 33. ISBN 0-08-044675-2.
- Klauck SM (2006). "Genetics of autism spectrum disorder" (PDF). European Journal of Human Genetics 14 (6): 714–720. doi:10.1038/sj.ejhg.5201610.
- National Institute of Neurological Disorders and Stroke (NINDS) (31 July 2007). "Asperger syndrome fact sheet". Archived from the original on 21 August 2007. Retrieved 24 August 2007. NIH Publication No. 05-5624.
- Clarke J, van Amerom G (2007). "'Surplus suffering': differences between organizational understandings of Asperger's syndrome and those people who claim the 'disorder'". Disabil Soc 22 (7): 761–76. doi:10.1080/09687590701659618.
- Baron-Cohen S (2002). "Is Asperger syndrome necessarily viewed as a disability?". Focus Autism Other Dev Disabl 17 (3): 186–91. doi:10.1177/10883576020170030801. A preliminary, freely readable draft, with slightly different wording in the quoted text, is in: Baron-Cohen S (2002). "Is Asperger's syndrome necessarily a disability?" (PDF). Cambridge: Autism Research Centre. Archived from the original on 17 December 2008. Retrieved 2 December 2008.
- Kasari C, Rotheram-Fuller E (2005). "Current trends in psychological research on children with high-functioning autism and Asperger disorder". Current Opinion in Psychiatry 18 (5): 497–501. doi:10.1097/01.yco.0000179486.47144.61. PMID 16639107.
- Witwer AN, Lecavalier L (2008). "Examining the validity of autism spectrum disorder subtypes". J Autism Dev Disord 38 (9): 1611–24. doi:10.1007/s10803-008-0541-2. PMID 18327636.
- Sanders JL (2009). "Qualitative or quantitative differences between Asperger's Disorder and autism? historical considerations". J Autism Dev Disord 39 (11): 1560–7. doi:10.1007/s10803-009-0798-0. PMID 19548078.
- Szatmari P (2000). "The classification of autism, Asperger's syndrome, and pervasive developmental disorder". Can J Psychiatry 45 (8): 731–38. PMID 11086556.
- Matson JL, Minshawi NF (2006). "History and development of autism spectrum disorders". Early intervention for autism spectrum disorders: a critical analysis. Amsterdam: Elsevier Science. p. 21. ISBN 0-08-044675-2.
- Schopler E (1998). "Premature popularization of Asperger syndrome". In Schopler E, Mesibov GB, Kunce LJ. Asperger syndrome or high-functioning autism?. New York: Plenum press. pp. 388–90. ISBN 0-306-45746-6.
- "DSM-5 development". American Psychiatric Association. 2010. Archived from the original on 13 February 2010. Retrieved 20 February 2010.
- Ghaziuddin M (2010). "Should the DSM V drop Asperger syndrome?". J Autism Dev Disord 40 (9): 1146–8. doi:10.1007/s10803-010-0969-z. PMID 20151184.
- Faras H, Al Ateeqi N, Tidmarsh L (2010). "Autism spectrum disorders". Ann Saudi Med 30 (4): 295–300. doi:10.4103/0256-4947.65261. PMC 2931781. PMID 20622347.
- World Health Organization (2006). "F84. Pervasive developmental disorders". International Statistical Classification of Diseases and Related Health Problems (10th (ICD-10) ed.). ISBN 92-4-154419-8. Retrieved 25 June 2007.
- Piven J, Palmer P, Jacobi D, Childress D, Arndt S (1997). "Broader autism phenotype: evidence from a family history study of multiple-incidence autism families" (PDF). Am J Psychiatry 154 (2): 185–90. PMID 9016266.
- Lord C, Cook EH, Leventhal BL, Amaral DG (2000). "Autism spectrum disorders". Neuron 28 (2): 355–63. doi:10.1016/S0896-6273(00)00115-X. PMID 11144346.
- American Psychiatric Association (2000). "Diagnostic criteria for 299.80 Asperger's Disorder (AD)". Diagnostic and Statistical Manual of Mental Disorders (4th, text revision (DSM-IV-TR) ed.). ISBN 0-89042-025-4. Retrieved 28 June 2007.
- Brasic JR (7 July 2010). "Asperger's Syndrome". Medscape eMedicine. Retrieved 25 November 2010.
- Allen D, Evans C, Hider A, Hawkins S, Peckett H, Morgan H (2008). "Offending behaviour in adults with Asperger syndrome". J Autism Dev Disord 38 (4): 748–58. doi:10.1007/s10803-007-0442-9. PMID 17805955.
- Tsatsanis KD (2003). "Outcome research in Asperger syndrome and autism". Child Adolesc Psychiatr Clin N Am 12 (1): 47–63. doi:10.1016/S1056-4993(02)00056-1. PMID 12512398.
- Newman SS, Ghaziuddin M (2008). "Violent crime in Asperger syndrome: the role of psychiatric comorbidity". J Autism Dev Disord 38 (10): 1848–52. doi:10.1007/s10803-008-0580-8. PMID 18449633.
- South M, Ozonoff S, McMahon WM (2005). "Repetitive behavior profiles in Asperger syndrome and high-functioning autism". J Autism Dev Disord 35 (2): 145–58. doi:10.1007/s10803-004-1992-8. PMID 15909401.
- Rapin I (2001). "Autism spectrum disorders: relevance to Tourette syndrome". Adv Neurol 85: 89–101. PMID 11530449.
- Roy M, Dillo W, Emrich HM, Ohlmeier MD (2009). "Asperger's syndrome in adulthood". Dtsch Arztebl Int 106 (5): 59–64. doi:10.3238/arztebl.2009.0059. PMC 2695286. PMID 19562011.
- Frith U (January 1996). "Social communication and its disorder in autism and Asperger syndrome". J. Psychopharmacol. (Oxford) 10 (1): 48–53. doi:10.1177/026988119601000108. PMID 22302727.
- Lyons V, Fitzgerald M (2004). "Humor in autism and Asperger syndrome". J Autism Dev Disord 34 (5): 521–31. doi:10.1007/s10803-004-2547-8. PMID 15628606.
- Filipek PA, Accardo PJ, Baranek GT, et al (1999). "The screening and diagnosis of autistic spectrum disorders". J Autism Dev Disord 29 (6): 439–84. doi:10.1023/A:1021943802493. PMID 10638459.
- Frith U (2004). "Emanuel Miller lecture: confusions and controversies about Asperger syndrome". J Child Psychol Psychiatry 45 (4): 672–86. doi:10.1111/j.1469-7610.2004.00262.x. PMID 15056300.
- Prior M, Ozonoff S (2007). "Psychological factors in autism". In Volkmar FR. Autism and Pervasive Developmental Disorders (2nd ed.). Cambridge University Press. pp. 69–128. ISBN 0-521-54957-4.
- Bogdashina O (2003). Sensory Perceptional Issues in Autism and Asperger Syndrome: Different Sensory Experiences, Different Perceptual Worlds. Jessica Kingsley. ISBN 1-84310-166-1.
- Rogers SJ, Ozonoff S (2005). "Annotation: what do we know about sensory dysfunction in autism? A critical review of the empirical evidence". J Child Psychol Psychiatry 46 (12): 1255–68. doi:10.1111/j.1469-7610.2005.01431.x. PMID 16313426.
- Ehlers S, Gillberg C (1993). "The epidemiology of Asperger's syndrome. A total population study". J Child Psychol Psychiat 34 (8): 1327–50. doi:10.1111/j.1469-7610.1993.tb02094.x. PMID 8294522.
- Polimeni MA, Richdale AL, Francis AJ (2005). "A survey of sleep problems in autism, Asperger's disorder and typically developing children". J Intellect Disabil Res 49 (4): 260–8. doi:10.1111/j.1365-2788.2005.00642.x. PMID 15816813.
- Tani P, Lindberg N, Joukamaa M, et al (2004). "Asperger syndrome, alexithymia and perception of sleep". Neuropsychobiology 49 (2): 64–70. doi:10.1159/000076412. PMID 14981336.
- Alexithymia and AS:
- Fitzgerald M, Bellgrove MA (2006). "The overlap between alexithymia and Asperger's syndrome". J Autism Dev Disord 36 (4): 573–6. doi:10.1007/s10803-006-0096-z. PMC 2092499. PMID 16755385.
- Hill E, Berthoz S (2006). "Response". J Autism Dev Disord 36 (8): 1143–5. doi:10.1007/s10803-006-0287-7. PMID 17080269.
- Lombardo MV, Barnes JL, Wheelwright SJ, Baron-Cohen S (2007). Zak, Paul, ed. "Self-referential cognition and empathy in autism". PLoS ONE 2 (9): e883. doi:10.1371/journal.pone.0000883. PMC 1964804. PMID 17849012.
- Foster B, King BH (2003). "Asperger syndrome: to be or not to be?". Current Opinion in Pediatrics 15 (5): 491–4. doi:10.1097/00008480-200310000-00008. PMID 14508298.
- Arndt TL, Stodgell CJ, Rodier PM (2005). "The teratology of autism". Int J Dev Neurosci 23 (2–3): 189–99. doi:10.1016/j.ijdevneu.2004.11.001. PMID 15749245.
- Rutter M (2005). "Incidence of autism spectrum disorders: changes over time and their meaning". Acta Paediatr 94 (1): 2–15. doi:10.1111/j.1651-2227.2005.tb01779.x. PMID 15858952.
- Müller RA (2007). "The study of autism as a distributed disorder". Ment Retard Dev Disabil Res Rev 13 (1): 85–95. doi:10.1002/mrdd.20141. PMC 3315379. PMID 17326118.
- Rinehart NJ, Bradshaw JL, Brereton AV, Tonge BJ (2002). "A clinical and neurobehavioural review of high-functioning autism and Asperger's disorder". Aust N Z J Psychiatry 36 (6): 762–70. doi:10.1046/j.1440-1614.2002.01097.x. PMID 12406118.
- Berthier ML, Starkstein SE, Leiguarda R (1990). "Developmental cortical anomalies in Asperger's syndrome: neuroradiological findings in two patients". J Neuropsychiatry Clin Neurosci 2 (2): 197–201. PMID 2136076.
- Happé F, Ronald A, Plomin R (2006). "Time to give up on a single explanation for autism". Nature Neuroscience 9 (10): 1218–20. doi:10.1038/nn1770. PMID 17001340.
- Just MA, Cherkassky VL, Keller TA, Kana RK, Minshew NJ (2007). "Functional and anatomical cortical underconnectivity in autism: evidence from an FMRI study of an executive function task and corpus callosum morphometry". Cereb Cortex 17 (4): 951–61. doi:10.1093/cercor/bhl006. PMID 16772313.
- Iacoboni M, Dapretto M (2006). "The mirror neuron system and the consequences of its dysfunction". Nature Reviews Neuroscience 7 (12): 942–51. doi:10.1038/nrn2024. PMID 17115076.
- Happé F, Frith U (2006). "The weak coherence account: detail-focused cognitive style in autism spectrum disorders". J Autism Dev Disord 36 (1): 5–25. doi:10.1007/s10803-005-0039-0. PMID 16450045.
- Mottron L, Dawson M, Soulières I, Hubert B, Burack J (2006). "Enhanced perceptual functioning in autism: an update, and eight principles of autistic perception". J Autism Dev Disord 36 (1): 27–43. doi:10.1007/s10803-005-0040-7. PMID 16453071.
- Ramachandran VS, Oberman LM (2006). "Broken mirrors: a theory of autism" (PDF). Sci Am 295 (5): 62–9. doi:10.1038/scientificamerican1106-62. PMID 17076085. Archived from the original on 5 February 2009. Retrieved 13 February 2009.
- Nishitani N, Avikainen S, Hari R (2004). "Abnormal imitation-related cortical activation sequences in Asperger's syndrome". Annals of Neurology 55 (4): 558–62. doi:10.1002/ana.20031. PMID 15048895.
- Baron-Cohen S, Leslie AM, Frith U (1985). "Does the autistic child have a 'theory of mind'?" (PDF). Cognition 21 (1): 37–46. doi:10.1016/0010-0277(85)90022-8. PMID 2934210. Archived from the original on 28 June 2007. Retrieved 28 June 2007.
- Baron-Cohen S (2006). "The hyper-systemizing, assortative mating theory of autism" (PDF). Prog Neuropsychopharmacol Biol Psychiatry 30 (5): 865–72. doi:10.1016/j.pnpbp.2006.01.010. PMID 16519981. Retrieved 8 June 2009.
- Szatmari P, Bremner R, Nagy J (1989). "Asperger's syndrome: a review of clinical features". Can J Psychiatry 34 (6): 554–60. PMID 2766209.
- Gillberg IC, Gillberg C (1989). "Asperger syndrome—some epidemiological considerations: a research note". J Child Psychol Psychiatry 30 (4): 631–8. doi:10.1111/j.1469-7610.1989.tb00275.x. PMID 2670981.
- Fitzgerald M, Corvin A (2001). "Diagnosis and differential diagnosis of Asperger syndrome". Adv Psychiatric Treat 7 (4): 310–8. doi:10.1192/apt.7.4.310.
- Leskovec TJ, Rowles BM, Findling RL (2008). "Pharmacological treatment options for autism spectrum disorders in children and adolescents". Harv Rev Psychiatry 16 (2): 97–112. doi:10.1080/10673220802075852. PMID 18415882.
- Tantam D (2003). "The challenge of adolescents and adults with Asperger syndrome". Child Adolesc Psychiatr Clin N Am 12 (1): 143–63. doi:10.1016/S1056-4993(02)00053-6. PMID 12512403.
- Uekermann J, Daum I (May 2008). "Social cognition in alcoholism: a link to prefrontal cortex dysfunction?". Addiction 103 (5): 726–35. doi:10.1111/j.1360-0443.2008.02157.x. PMID 18412750.
- Shattuck PT, Grosse SD (2007). "Issues related to the diagnosis and treatment of autism spectrum disorders". Ment Retard Dev Disabil Res Rev 13 (2): 129–35. doi:10.1002/mrdd.20143. PMID 17563895.
- Klin A, Volkmar FR (2003). "Asperger syndrome: diagnosis and external validity". Child Adolesc Psychiatr Clin N Am 12 (1): 1–13. doi:10.1016/S1056-4993(02)00052-4. PMID 12512395.
- Toth K, King BH (2008). "Asperger's syndrome: diagnosis and treatment". Am J Psychiatry 165 (8): 958–63. doi:10.1176/appi.ajp.2008.08020272. PMID 18676600.
- The CAST has been renamed from the Childhood Asperger Syndrome Test to the Childhood Autism Spectrum Test, reflecting the removal of Asperger's Syndrome from the DSM-5
- Campbell JM (2005). "Diagnostic assessment of Asperger's disorder: a review of five third-party rating scales". J Autism Dev Disord 35 (1): 25–35. doi:10.1007/s10803-004-1028-4. PMID 15796119.
- Auyeung B, Baron-Cohen S, Wheelwright S, Allison C (2008). "The Autism Spectrum Quotient: Children's Version (AQ-Child)" (PDF). J Autism Dev Disord 38 (7): 1230–40. doi:10.1007/s10803-007-0504-z. PMID 18064550. Archived from the original on 5 February 2009. Retrieved 2 January 2009.
- Baron-Cohen S, Hoekstra RA, Knickmeyer R, Wheelwright S (2006). "The Autism-Spectrum Quotient (AQ)—adolescent version" (PDF). J Autism Dev Disord 36 (3): 343–50. doi:10.1007/s10803-006-0073-6. PMID 16552625. Archived from the original on 5 February 2009. Retrieved 2 January 2009.
- Woodbury-Smith MR, Robinson J, Wheelwright S, Baron-Cohen S (2005). "Screening adults for Asperger Syndrome using the AQ: a preliminary study of its diagnostic validity in clinical practice" (PDF). J Autism Dev Disord 35 (3): 331–5. doi:10.1007/s10803-005-3300-7. PMID 16119474. Archived from the original on 17 December 2008. Retrieved 2 January 2009.
- Khouzam HR, El-Gabalawi F, Pirwani N, Priest F (2004). "Asperger's disorder: a review of its diagnosis and treatment". Compr Psychiatry 45 (3): 184–91. doi:10.1016/j.comppsych.2004.02.004. PMID 15124148.
- Attwood T (2003). "Frameworks for behavioral interventions". Child Adolesc Psychiatr Clin N Am 12 (1): 65–86. doi:10.1016/S1056-4993(02)00054-8. PMID 12512399.
- Krasny L, Williams BJ, Provencal S, Ozonoff S (2003). "Social skills interventions for the autism spectrum: essential ingredients and a model curriculum". Child Adolesc Psychiatr Clin N Am 12 (1): 107–22. doi:10.1016/S1056-4993(02)00051-2. PMID 12512401.
- Myles BS (2003). "Behavioral forms of stress management for individuals with Asperger syndrome". Child Adolesc Psychiatr Clin N Am 12 (1): 123–41. doi:10.1016/S1056-4993(02)00048-2. PMID 12512402.
- Towbin KE (2003). "Strategies for pharmacologic treatment of high functioning autism and Asperger syndrome". Child Adolesc Psychiatr Clin N Am 12 (1): 23–45. doi:10.1016/S1056-4993(02)00049-4. PMID 12512397.
- Paul R (2003). "Promoting social communication in high functioning individuals with autistic spectrum disorders". Child Adolesc Psychiatr Clin N Am 12 (1): 87–106. doi:10.1016/S1056-4993(02)00047-0. PMID 12512400.
- Matson JL (2007). "Determining treatment outcome in early intervention programs for autism spectrum disorders: a critical analysis of measurement issues in learning based interventions". Res Dev Disabil 28 (2): 207–18. doi:10.1016/j.ridd.2005.07.006. PMID 16682171.
- Rao PA, Beidel DC, Murray MJ (2008). "Social skills interventions for children with Asperger's syndrome or high-functioning autism: a review and recommendations". J Autism Dev Disord 38 (2): 353–61. doi:10.1007/s10803-007-0402-4. PMID 17641962.
- Sofronoff K, Leslie A, Brown W (2004). "Parent management training and Asperger syndrome: a randomized controlled trial to evaluate a parent based intervention". Autism 8 (3): 301–17. doi:10.1177/1362361304045215. PMID 15358872.
- Newcomer JW (2007). "Antipsychotic medications: metabolic and cardiovascular risk". J Clin Psychiatry 68 (suppl 4): 8–13. PMID 17539694.
- Chavez B, Chavez-Brown M, Sopko MA, Rey JA (2007). "Atypical antipsychotics in children with pervasive developmental disorders". Pediatr Drugs 9 (4): 249–66. doi:10.2165/00148581-200709040-00006. PMID 17705564.
- Staller J (2006). "The effect of long-term antipsychotic treatment on prolactin". J Child Adolesc Psychopharmacol 16 (3): 317–26. doi:10.1089/cap.2006.16.317. PMID 16768639.
- Stachnik JM, Nunn-Thompson C (2007). "Use of atypical antipsychotics in the treatment of autistic disorder". Annals of Pharmacotherapy 41 (4): 626–34. doi:10.1345/aph.1H527. PMID 17389666.
- Blacher J, Kraemer B, Schalow M (2003). "Asperger syndrome and high functioning autism: research concerns and emerging foci". Current Opinion in Psychiatry 16 (5): 535–542. doi:10.1097/00001504-200309000-00008.
- Coplan J, Jawad AF (2005). "Modeling clinical outcome of children with autistic spectrum disorders". Pediatrics 116 (1): 117–22. doi:10.1542/peds.2004-1118. PMID 15995041. Lay summary – press release (5 July 2005).
- Chiang HM, Lin YH (2007). "Mathematical ability of students with Asperger syndrome and high-functioning autism" (PDF). Autism 11 (6): 547–56. doi:10.1177/1362361307083259. PMID 17947290. Archived from the original on 7 April 2009. Retrieved 6 March 2009. – via SAGE Journals (subscription required)
- Herera S (25 February 2005). "Mild autism has 'selective advantages'". CNBC. Archived from the original on 1 November 2007. Retrieved 14 November 2007.
- Moran M (2006). "Asperger's may be answer to diagnostic mysteries". Psychiatr News 41 (19): 21.
- Gillberg C (2008). "Asperger syndrome—mortality and morbidity". In Rausch JL, Johnson ME, Casanova MF (eds.). Asperger's Disorder. Informa Healthcare. pp. 63–80. ISBN 0-8493-8360-9.
- Fombonne E, Tidmarsh L (2003). "Epidemiologic data on Asperger disorder". Child Adolesc Psychiatr Clin N Am 12 (1): 15–21. doi:10.1016/S1056-4993(02)00050-0. PMID 12512396.
- Fombonne E (2007). "Epidemiological surveys of pervasive developmental disorders". In Volkmar FR. Autism and Pervasive Developmental Disorders (2nd ed.). Cambridge University Press. pp. 33–68. ISBN 0-521-54957-4.
- Mattila ML, Kielinen M, Jussila K, et al (2007). "An epidemiological and diagnostic study of Asperger syndrome according to four sets of diagnostic criteria". J Am Acad Child Adolesc Psychiatry 46 (5): 636–46. doi:10.1097/chi.0b013e318033ff42. PMID 17450055.
- Cederlund M, Gillberg C (2004). "One hundred males with Asperger syndrome: a clinical study of background and associated factors". Dev Med Child Neurol 46 (10): 652–60. doi:10.1111/j.1469-8749.2004.tb00977.x. PMID 15473168.
- Gillberg C, Billstedt E (2000). "Autism and Asperger syndrome: coexistence with other clinical disorders". Acta Psychiatr Scand 102 (5): 321–30. doi:10.1034/j.1600-0447.2000.102005321.x. PMID 11098802.
- Baron-Cohen S, Klin A (2006). "What's so special about Asperger Syndrome?" (PDF). Brain Cogn 61 (1): 1–4. doi:10.1016/j.bandc.2006.02.002. PMID 16563588.
- Lyons V, Fitzgerald M (2007). "Did Hans Asperger (1906–1980) have Asperger Syndrome?". J Autism Dev Disord 37 (10): 2020–1. doi:10.1007/s10803-007-0382-4. PMID 17917805.
- Osborne L (2002). American Normal: The Hidden World of Asperger Syndrome. Copernicus. p. 19. ISBN 0-387-95307-8.
- Hippler K, Klicpera C (February 2003). "A retrospective analysis of the clinical case records of 'autistic psychopaths' diagnosed by Hans Asperger and his team at the University Children's Hospital, Vienna". Philosophical Transactions of the Royal Society B 358 (1430): 291–301. doi:10.1098/rstb.2002.1197. PMC 1693115. PMID 12639327.
- Wing L (1991). "The relationship between Asperger's syndrome and Kanner's autism". In Frith U. Autism and Asperger syndrome. Cambridge University Press. pp. 93–121. ISBN 0-521-38608-X.
- Wing L (1981). "Asperger's syndrome: a clinical account". Psychol Med 11 (1): 115–29. doi:10.1017/S0033291700053332. PMID 7208735. Archived from the original on 17 August 2007. Retrieved 15 August 2007.
- Willey LH (1999). Pretending to be Normal: Living with Asperger's Syndrome. Jessica Kingsley. pp. 71, 104. ISBN 1-85302-749-9.
- Williams CC (2005). "In search of an Asperger". In Stoddart KP. Children, Youth and Adults with Asperger Syndrome: Integrating Multiple Perspectives. Jessica Kingsley. pp. 242–52. ISBN 1-84310-319-2. "The life prospects of people with AS would change if we shifted from viewing AS as a set of dysfunctions, to viewing it as a set of differences that have merit."
- Dakin CJ (2005). "Life on the outside: A personal perspective of Asperger syndrome". In Stoddart KP. Children, Youth and Adults with Asperger Syndrome: Integrating Multiple Perspectives. Jessica Kingsley. pp. 352–61. ISBN 1-84310-319-2.
- Clarke J, van Amerom G (2008). "Asperger's syndrome: differences between parents' understanding and those diagnosed". Soc Work Health Care 46 (3): 85–106. doi:10.1300/J010v46n03_05. PMID 18551831.
- Allred S (2009). "Reframing Asperger syndrome: lessons from other challenges to the Diagnostic and Statistical Manual and ICIDH approaches". Disabil Soc 24 (3): 343–55. doi:10.1080/09687590902789511.
- Baron-Cohen S (2008). "The evolution of brain mechanisms for social behavior". In Crawford C, Krebs D (eds.). Foundations of Evolutionary Psychology. Lawrence Erlbaum. pp. 415–32. ISBN 0-8058-5957-8.