Howlin, P. (2003) Outcome in High-Functioning Adults with Autism With and Without Early Language Delays: Implications for the Differentiation Between Autism and Asperger Syndrome or Impairment. Journal of Autism and Developmental Disorders, 33 (1), 1-13.
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 was designated as having Asperger’s 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 (Howlin, 2008).
The researchers in the present study attempted to address 3 questions in their study. First, do individuals diagnosed with High Functioning Autism (HFA) differ in terms of early symptoms from those individuals diagnosed with Asperger’s syndrome (AS)? Second, is there a significant difference between socialization, communication, and stereotypical behaviors between those individuals diagnosed with HFA, and those diagnosed with AS? Lastly, are there significant differences with language between those diagnosed with HFA and AS?
Participants used in the present study were 34 adults diagnosed with HFA and 42 adults diagnosed with AS. All participants needed to meet certain criteria to be included in the current study. Criteria for participation included a diagnosis of either High Functioning Autism or Asperger’s syndrome based off of the Autism Diagnostic Interview-Revised (ADI-R), clinical records, and current functional assessments based off of parent reports. Participants also needed to be at least 18 years of age, and received a nonverbal IQ score of 70 or greater. Groups were matched and assigned based on age, gender, and nonverbal IQ scores.
Measures used in the present study included Raven’s Matrices, the Wechsler Adult Intelligence Scale (WAIS-R) to assess participant’s nonverbal IQ scores. Word comprehension and vocabulary was assessed using the British Picture Vocabulary Scale, and the One Word Picture Vocabulary Test. Communication, Socialization, and stereotypies were assessed using the Autism Diagnostic Interview-Revised (ADI-R).
Findings from the current study suggest that there should be no difference between those diagnosed with HFA and those diagnosed with AS. Significant differences were found between individuals with HFA and AS when participants were matched based only on their IQ scores. Parent reports also show differences between the groups, but only at earlier ages.
The present study was interesting in regards to the current and ongoing debate of eliminating the AS and HFA diagnosis from the DSM-IV. It was interesting to read that the findings of the current study are in support of not distinguishing between the two diagnoses. Some of the limitations I found within the study are the measurements used. Reliability was not reported in the study with some of the assessments. Measurements can often be found to very subjective, especially when you are relying on retrospective reports from parents.