WASHINGTON — Officially, the lack of delayed language skills is what separates a child with Asperger's disorder from one with high-functioning autism. But the reality is far more complex, Dr. Chris Plauche Johnson said at the annual meeting of the American Academy of Pediatrics.
Both Asperger's disorder and autism are included in the Diagnostic and Statistical Manual-IV, Text Revision (DSM-IV-TR) under “Pervasive Developmental Disorders,” a term which itself is now falling out of use in favor of “autism spectrum disorders.” Asperger's disorder is a unique diagnostic category in DSM-IV-TR, while children who meet the criteria for autism except for having normal intelligence are often classified under “atypical autism.”
Both Asperger's and high-functioning autism share criteria regarding social skills and restricted interests, but they differ in language ability and age of onset. However, not everyone agrees that the two are actually separate entities, and some experts feel the DSM-IV-TR criteria for Asperger's disorder are too restrictive, said Dr. Johnson, a developmental pediatrician and clinical professor of pediatrics at the University of Texas Health Science Center, San Antonio.
The American Academy of Pediatrics plans to issue a revised clinical report on autism spectrum disorders sometime in 2006–2007, she said.
Unlike autism, for which the parents' first concern is about language development and which arises when the child is 18–24 months old, parents of children with Asperger's disorder often don't become concerned until the child is in preschool and has difficulties with peer social interactions or in general behavior.
But the syndromes are beginning to blend now that comorbid mental retardation is being diagnosed less and less often among children with autism. Before 1990, about 90% of autistic children also had mental retardation. Now the rate has dropped to 50% or even lower in some studies. A major reason for this is that better diagnostic tools and improved clinician training have reduced the number of children whose intelligence was considered “untestable” and who therefore were listed as mentally retarded.
These days, it's highly unusual for a child to be considered untestable, which calls into question the whole phenomenon of atypical autism. “High-functioning autism may not be atypical in the new millennium,” Dr. Johnson said.
But even children with high-functioning autism have delayed speech, with few words or with inconsistent, “pop-up” use of words. They may be able to label things or repeat song lyrics or phrases, but have difficulty constructing meaningful sentences on their own. They often don't respond to verbal or body language cues from others, and may interrupt others. In contrast, children with Asperger's disorder have no significant delay in language.
Any child suspected of having either disorder should be referred for comprehensive testing so that interventions such as speech and social skills training can begin early. In the end, the diagnosis may hinge on practical issues: Insurance companies, for example, will usually pay for therapy for autism but not always for Asperger's.
How the Criteria Delineate the Two
According to the DSM-IV-TR, criteria for autism and Asperger's disorder include:
In both autistic disorder and Asperger's disorder, there is qualitative impairment in social interaction, as manifested by at least two of the following:
Marked impairment in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body postures, and gestures to regulate social interaction.
Failure to develop peer relationships appropriate to developmental level.
A lack of spontaneous seeking to share enjoyment, interests, or achievements with other people.
Lack of social or emotional reciprocity.
In both autistic disorder and Asperger's disorder, there are restricted, repetitive, and stereotyped patterns of behavior, interests, and activities, as manifested by at least one of the following:
Encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus.
Apparently inflexible adherence to specific, nonfunctional routines or rituals.
Stereotyped and repetitive motor mannerisms (hand or finger flapping or twisting, or complex whole-body movements).
Persistent preoccupation with parts of objects.
In autistic disorder, there are qualitative impairments in communication as manifested by at least one of the following:
Delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime).
In individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others.
Stereotyped and repetitive use of language or use of idiosyncratic language.
Lack of varied, spontaneous, make-believe play or social imitative play appropriate to developmental level.
Conversely, in Asperger's disorder, there is no clinically significant general delay in language (single words used by age 2 years, communicative phrases by age 3 years).