Outcome in High-Functioning Adults with Autism with and Without Early Language Delays: Implications for the Differentiation Between Autism and Asperger Syndrome

Journal of Autism and Developmental Disorders, Feb 2003

The question of whether Asperger syndrome and high-functioning autism should be considered as the same or different conditions has been a source of debate and controversy over recent years. In the present study, 34 adults with autism who had shown early delays in language were compared with 42 individuals who were reported to have had no such delays, either in their use of words or phrases. All participants were at least 18 years of age, had a nonverbal IQ of 70 or above and met ADI-R criteria for age of onset, communication and social impairments, and stereotyped behaviors. Those in the language delay group were diagnosed as having high-functioning autism. The remainder were designated as having Asperger syndrome. The groups were matched for age, nonverbal IQ and gender. No significant differences were found between the groups either in their total ADI-R algorithm scores, or in their algorithm scores on individual domains. Social outcome ratings and ADI-R scores based on current functioning also failed to differentiate between the groups. Scores on tests of language comprehension and expression were also similar, but in both groups language abilities were well below chronological age level. The implications of these results with respect to the differences between Asperger syndrome and high-functioning autism are discussed. The poor performance on language tests also challenges the assumption that early language development in Asperger syndrome is essentially normal.

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Outcome in High-Functioning Adults with Autism with and Without Early Language Delays: Implications for the Differentiation Between Autism and Asperger Syndrome

Journal of Autism and Developmental Disorders Outcome in High-Functioning Adults with Autism With and Without Early Language Delays: Implications for the Differentiation Between Autism and Asperger Syndrome Patricia Howlin 0 0 Department of Psychology, St. George's Hospital Medical School , Cranmer Terrace, London SW17 ORE , U.K. The question of whether Asperger syndrome and high-functioning autism should be considered as the same or different conditions has been a source of debate and controversy over recent years. In the present study, 34 adults with autism who had shown early delays in language were compared with 42 individuals who were reported to have had no such delays, either in their use of words or phrases. All participants were at least 18 years of age, had a nonverbal IQ of 70 or above and met ADI-R criteria for age of onset, communication and social impairments, and stereotyped behaviors. Those in the language delay group were diagnosed as having high-functioning autism. The remainder were designated as having Asperger syndrome. The groups were matched for age, nonverbal IQ and gender. No significant differences were found between the groups either in their total ADI-R algorithm scores, or in their algorithm scores on individual domains. Social outcome ratings and ADI-R scores based on current functioning also failed to differentiate between the groups. Scores on tests of language comprehension and expression were also similar, but in both groups language abilities were well below chronological age level. The implications of these results with respect to the differences between Asperger syndrome and high-functioning autism are discussed. The poor performance on language tests also challenges the assumption that early language development in Asperger syndrome is essentially normal. High-functioning autism; Asperger syndrome; long-term outcome INTRODUCTION The issue of whether autism and Asperger syndrome are different conditions (albeit part of the same spectrum of disorders) has been a source of continuing debate over recent years (cf. Klin, Volkmar, & Sparrow, 2000; Schopler, Mesibov, & Kunce, 1998). There is also considerable disagreement about the validity of the diagnostic criteria used in DSM-IV (APA, 1994) and ICD-10 (WHO, 1992) to distinguish between the two conditions, (Kim, Szatmari, Bryson, Streiner, & Wilson, 2000; Kugler, 1998; Leekam, Libby, Wing, Gould, & Gillberg, 2000; Manjiviona & Prior, 1999). Indeed, several studies now suggest that if strict DSM/ICD criteria are applied, a diagnosis of Asperger syndrome becomes unlikely, or even impossible (Eisenmajer et al., 1996; Ghaziuddin, Tsai & Ghaziuddin, 1992; Manjiviona & Prior, 1995; Mayes & Calhoun, 2001; Miller & Ozonoff, 1997; Szatmari, Archer, Fisman, Streiner & Wilson, 1995). Wing, having been responsible for first bringing Aspergers original writings to the attention of clinicians in 1981, now expresses her concern that she may have opened a Pandoras box (Wing, 2000). Her original intention, to emphasize the fact that there was no evidence for a distinction between Asperger syndrome and autism, has frequently been overlooked. Instead, her account led to widespread research into the possible differences between the two conditions. Inadequate group matchings, small samples, and, above all, lack of agreement on diagnostic criteria have meant that few of these studies have produced any conclusive results (c.f. Klin et al., 2000). Despite this, the differential diagnosis can have implications for services, with individuals diagnosed as having Asperger syndrome or Asperger disorder sometimes being deprived of the level of support that is offered to those diagnosed as having autism (Klin & Volkmar, 2000; Department of Health, 2001). Current Research Evidence A systematic search of the literature over the past 15 years, using the major databases (MEDLINE, PsychINFO, etc.) was conducted together with an additional trawl of journals with a focus on developmental disorders (Journal of the American Academy of Child and Adolescent Psychiatry, Journal of Child Psychology and Psychiatry, Journal of Autism and Developmental Disorders, Autism, etc.), and recent collections of chapters in edited volumes (Klin et al., 2000; Schopler et al., 1998). Twenty-six separate studies were identified in which a direct comparison between individuals with high-functioning autism (HFA) (IQ 701) and Asperger syndrome had been conducted and in which diagnostic criteria and measures of IQ were adequately specified. Tables I and II summarize these studies, indicating the general areas investigated, the diagnostic systems used, the number and ages of participants, and the general conclusions of each. Table I. Summary of Findings in Studies Comparing Individuals with Asperger Syndrome and High-Functioning Autism Matched for Full-Scale IQ General clinical characteristics 1. Szatmari et al., 1990 (Wings criteria) Age Mean (range) HFA 23, AS14 yr 2. Mayes (...truncated)


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Patricia Howlin. Outcome in High-Functioning Adults with Autism with and Without Early Language Delays: Implications for the Differentiation Between Autism and Asperger Syndrome, Journal of Autism and Developmental Disorders, 2003, pp. 3-13, Volume 33, Issue 1, DOI: 10.1023/A:1022270118899