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Asperger Syndrome: General Information and Across the Lifespan (page 2)

By Stephen Bauer, MD, MPH
MAAP Services for Autism and Asperger Syndrome

Epidemiology

The best studies that have been carried out to date suggest that AS is considerably more common than "classic" Autism. Whereas Autism has traditionally been felt to occur in about 4 out of every 10,000 children, estimates of Asperger syndrome have ranged as high as 20-25 per 10,000. That means that for each case of more typical Autism, schools can expect to encounter several children with a picture of AS (that is even more true for the mainstream setting, where most children with AS will be found). In fact, a careful, population-based epidemiological study carried out by Gillberg's group in Sweden, concluded that nearly 0.7% of the children studied had a clinical picture either diagnostic of or suggestive of AS to some degree. Particularly if one includes those children who have many of the features of AS and seem to be milder presentations along the spectrum as it shades into "normal," it seems not to be a rare condition.

All studies have agreed that Asperger syndrome is much more common in boys than in girls. The reasons for this are unknown. AS is fairly commonly associated with other types of diagnoses, again for unknown reasons, including: tic disorders such as Tourette disorder, attentional problems, and mood problems such as depression and anxiety. In some cases there is a clear genetic component, with one parent (most often the father), showing either the full picture of AS or at least some of the traits associated with AS; genetic factors seem to be more common in AS compared to more classic Autism. Temperamental traits such as having intense and limited interests, compulsive or rigid style, and social awkwardness or timidity also seem to be more common, alone or in combination, in relatives of AS children. Sometimes there will be a positive family history of Autism in relatives, strengthening the impression that AS and Autism are sometimes related conditions. Other studies have demonstrated a fairly high rate of depression, both bipolar and unipolar, in relatives of children with AS, suggesting a genetic link in at least some cases. It seems likely that for AS, as for Autism, the clinical picture we see is probably influenced by many factors, including genetic ones, so that there is no single identifiable cause in most cases.

Definition

The new DSM-4 criteria for a diagnosis of AS, with much of the language carrying over from the diagnostic criteria for Autism, include the presence of:

  • Qualitative impairment in social interaction involving some or all of the following: impaired use of nonverbal behaviors to regulate social interaction, failure to develop age-appropriate peer relationships, lack of spontaneous interest in sharing experiences with others, and lack of social or emotional reciprocity.
  • Restricted, repetitive, and stereotyped patterns of behavior, interests, and activities involving: preoccupation with one or more stereotyped and restricted pattern of interest, inflexible adherence to specific nonfunctional routines or rituals, stereotyped or repetitive motor mannerisms, or preoccupation with parts of objects.

These behaviors must be sufficient to interfere significantly with social or other areas of functioning. Furthermore, there must be no significant associated delay in either general cognitive function, self-help/adaptive skills, interest in the environment, or overall language development.

Christopher Gillberg, a Swedish physician who has studied AS extensively, has proposed six criteria for the diagnosis, elaborating upon the criteria set forth in DSM-4. His six criteria capture the unique style of these children, and include:

  • Social impairment with extreme egocentricity, which may include:
    • Inability to interact with peers
    • Lack of desire to interact with peers
    • Poor appreciation of social cues
    • Socially and emotionally inappropriate responses
  • Limited interests and preoccupations, including:
    • More rote than meaning
    • Relatively exclusive of other interests
    • Repetitive adherence
  • Repetitive routines or rituals, that may be:
    • Imposed on self, or
    • Imposed on others
  • Speech and language peculiarities, such as:
    • Delayed early development possible but not consistently seen - Superficially perfect expressive language
    • Odd prosody, peculiar voice characteristics
    • Impaired comprehension including misinterpretation of literal and implied meanings.
  • Nonverbal communication problems, such as:
    • Limited use of gesture
    • Clumsy body language
    • Limited or inappropriate facial expression
    • Peculiar "stiff" gaze
    • Difficulty adjusting physical proximity
  • Motor clumsiness
    • May not be necessary part of the picture in all cases
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