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

Howlin P
Department of Psychology, St. George's Hospital Medical School, Cranmer Terrace, London SW17 ORE, UK.

Abstract: J Autism Dev Disord. 2003 Feb;33(1):3-13

Findings

The question of whether Asperger syndrome and high-functioning autism should be considered the same or different conditions has been debated in recent years. Overall, there appears to be no consistent evidence that there are any clinical or psychological differences between the two disorders. Also, there are suggestions that differences between these disorders found in early childhood may decrease with age. Some investigators suggested that Asperger children generally have better developed verbal skills.

Few studies have examined differences in these groups beyond mid adolescence, and it is possible that the apparent linguistic superiority of the Asperger groups might reduce with age. Therefore, Dr. Howlin studied differences in older individuals, all aged 18+, and all with a nonverbal IQ of at least 70. She selected 34 adults (25 men, 9 women) diagnosed with high-functioning autism, who had shown early delays in language and compared them with 42 individuals (35 men, 7 women) with no language delays who were diagnosed with Asperger syndrome. All subjects were matched for age nonverbal IQ and gender.

Parent or guardian-provided ADI-R scores were calculated—these measured impairments in communication, social interactions, and repetitive and stereotyped behaviors and interests. There were no statisically significant differences between the two groups in ratings of current social functioning. Scores on tests of language comprehension and expression were also similar, but in both groups language abilities were well below chronological age level.

Conclusions

Overall, this study confirmed findings that there are no consistent differences in social skills, communication skills, and repetitive/stereotyped behaviors between individuals with high-functioning autism and Asperger syndrome, and showed that as currently functioning, the two groups were comparable. The authors suggest that any distinctions in early childhood may become less marked with age. The age at which parents first noticed symptoms of abnormal development was somewhat earlier in the autism group, but this was only marginally statisically significant. However, results suggested that these early differences decreased over time. The poor performance on language tests also challenges the assumption that early language development in Asperger syndrome is essentially normal.