Outcome in high-functioning adults with autism with and without early language delays: Implications for the differentiation between autism and Asperger syndrome.

Patricia Howlin

Journal of Autism and Developmental Disorders 33(1): 3-13. 2003.

Question: Does early language delay differentiate the diagnosis of high functioning autism from Asperger syndrome?

Background: Getting an accurate diagnosis for a child may have implications for their treatment now and for their future functioning. There has been some controversy in the past about whether there is a real distinction between high functioning autism and Asperger syndrome, such that it would mean that there should be differences in treatment and planning for the child’s future. This study looks at whether early language acquisition and continuing language skills may differentiate between high functioning autism and Asperger syndrome.

Design: Two group comparison study.

Setting: Specialist clinic for adults with developmental disorders.

Patients: Seventy-six adults 18 years of age and over with an assessed nonverbal IQ of 70 or above, who met the diagnostic criteria for autism or Asperger syndrome based on the ADI-R, previous medical records, recent reports, and an assessment of their current functioning. Participants were divided into two groups according to their diagnosis and matched according to age, nonverbal IQ and gender.

Assessment of Prognostic Factors: Word comprehension and vocabulary were tested, and social functioning was determined by parental report on the ADI-R.

Main Outcome Measures: Evaluation of word comprehension using the British Picture Vocabulary Scale and of vocabulary using the Expressive One Word Picture Vocabulary Test. Social outcome ratings were used, as were ADI-R scores.

Main Results: Most common early symptoms of abnormal development noted by the parent were, in order of occurrence: language problems, motor development delays, social abnormalities, and behaviour problems in autism. In children with Asperger syndrome, parents reported that behaviour problems were what first prompted concerns, followed by repetitive and stereotyped behaviours, motor development problems, social abnormalities, and language delays.

Parents who were able to accurately recall ages for specific events said that their children with autism first used words at about three years and children with Asperger syndrome did so at a little over 1 year. Age at first use of word phrases was over 4 years for children with autism and just over 2 years for children with Asperger syndrome.

Tests of current language skills only marginally favoured the people with Asperger syndrome.

Conclusions: Although there were some differences noted during early childhood, most particularly around age of onset of developmental concerns and reaching of milestones, the differences faded with the onset of adulthood. This study could not conclude that High Functioning Autism and Asperger syndrome are distinct conditions. The author concludes that all people with High Functioning Autism and Asperger syndrome need the same kinds of community supports.