Asperger Syndrome

Asperger syndrome is an autism spectrum disorder, and people with it therefore show significant difficulties in social interaction, along with 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 use of language are frequently reported.

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

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 individuals improve over time, but difficulties with communication, social adjustment and independent living continue into adulthood. 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.

Classification

Asperger syndrome (AS) is one of the autism spectrum disorders (ASD) or pervasive developmental disorders (PDD), which are a spectrum of psychological conditions that are characterized by abnormalities of social interaction and communication that pervade the individual's functioning, and by restricted and repetitive interests and behavior. Like other psychological development disorders, ASD begins in infancy or childhood, has a steady course without remission or relapse, and has impairments that result from maturation-related changes in various systems of the brain. ASD, in turn, is a subset of the broader autism phenotype (BAP), which describes individuals who may not have ASD but do have autistic-like traits, such as social deficits. 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.

The extent of the overlap between AS and high-functioning autism (HFA—autism unaccompanied by mental retardation) is unclear. The current ASD classification is to some extent an artifact of how autism was discovered, and may not reflect the true nature of the spectrum. One of the proposed changes in DSM-V, set to be released in 2012, would eliminate Asperger syndrome as a separate diagnosis, and fold it under autism spectrum disorders, which would be rated on a severity scale.

Asperger syndrome is also called Asperger's syndrome (AS), Asperger (or Asperger's) disorder (AD), or just Asperger's. There is little consensus among clinical researchers about whether the condition's name should end in "syndrome" or "disorder".

Characteristics

A pervasive developmental disorder, Asperger syndrome is distinguished by a pattern of symptoms rather than a single symptom. It is characterized by qualitative impairment in social interaction, by stereotyped and restricted patterns of behavior, activities and interests, and by no clinically significant delay in cognitive development or general delay in language. 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.

Causes

Hans Asperger described common symptoms among his patients' family members, especially fathers, and research supports this observation and suggests a genetic contribution to Asperger syndrome. Although no specific gene has yet been identified, multiple factors are believed to play a role in the expression of autism, given the phenotypic variability seen in this group of children. 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.

Diagnosis

Standard diagnostic criteria require impairment in social interaction and repetitive and stereotyped patterns of behavior, activities and interests, without significant delay in language or cognitive development. Unlike the international standard, U.S. criteria also require significant impairment in day-to-day functioning. 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 current "gold standard" in diagnosing ASDs combines clinical judgment with the Autism Diagnostic Interview-Revised (ADI-R)—a semistructured parent interview—and the Autism Diagnostic Observation Schedule (ADOS)—a conversation and play-based interview with the child. 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 and bipolar disorder.

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 do not have autism but have social difficulties. In 2006, it was reported to be the fastest-growing psychiatric diagnosis in Silicon Valley children; also, there is a predilection for adults to self-diagnose it. 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.

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