This episode of Verbatim finds autism researchers and clinicians wrestling in various ways with the (apparently) elusive concept of autism severity:
Note that in several cases, formal criteria for Autistic Disorder were met but a diagnosis of PDD-NOS or Asperger’s Disorder was given to the family. The reason for this was that the child had previously been given a diagnosis of PDD-NOS or Asperger’s and had continued to improve so that symptoms were fewer or milder than they had been. It was considered to be counterproductive to give the parents a more severe diagnosis when the child had actually shown significant improvement, and in many cases, the symptoms were present but in relatively mild form. (Kelley et al., 2006)
Indeed, in some ways, children with AS [Asperger syndrome] are more severe than those with autism as the discrepancy between their intellectual potential and their actual adaptation in terms of socialization and communication is so very marked; they look so "normal" but their behavior is so "odd." There is also some evidence that adolescents with AS have more symptoms of anxiety and depression than do children with autism (Szatmari et al., 1989), although the mechanism for this finding may only be that they have the ability to communicate their distress more readily. In this context, they have the more severe disorder because they have better communcation skills. It all depends on what dimension of severity one is talking about. (Szatmari, 2000)
References:
Kelley, E., Paul, J.J., Fein, D., & Naigles, L.R. (2006). Residual language deficits in optimal outcome children with a history of autism. Journal of Autism and Developmental Disorders, 36, 807-828.
Szatmari, P. (2000). Perpectives on the classification of Asperger syndrome. In A. Klin, F.R. Volkmar & S.S. Sparrow (Eds.), Asperger Syndrome (pp. 403-417). New York: Guilford.
Szatmari, P., Bartolucci, G., & Bremner, R. (1989). Asperger's syndrome and autism: Comparisons on early history and outcome. Developmental Medicine and Child Neurology, 31, 709-720.