Two-year outcome of preschool children with autism or Asperger's syndrome

Objective: DSM-IV specifies that Asperger's disorder is a type of pervasive developmental disorder without clinically significant cognitive or languag e delay. There are no data, however, on the outcome of children with Asperg er's disorder or on whether their outcome differs from that of children wit h autism. The objectives of this study were to compare the outcome of group s of children with these disorders over a period of 2 yea rs on variables i ndependent of the defining criteria and to identify variables that might ac count for these differences. Method: All children 4-6 years of age who came for assessment or were curre ntly in treatment at a pervasive developmental disorder service of one of s everal centers in a large geographic region were identified. Children who r eceived a diagnosis of autism (N=46) or Asperger's syndrome (N=20) on the b asis of a diagnostic interview and had an IQ in the nonretarded range were given a battery of cognitive, language, and behavioral tests. Families were contacted roughly 2 yea rs after the date of their enrollment in the study , and many of the tests were readministered. Results: Children with Asperger's syndrome had better social skills and few er autistic symptoms 2 years after study enrollment than the children with autism. The differences in outcome could not be explained by initial differ ences in IQ and language abilities. Children with autism who had developed verbal fluency at follow-up were very similar to the children with Asperger 's syndrome at study enrollment. Conclusions: Although the exact mechanism for the differences in outcome re main to be determined, it appears that Asperger's disorder and autism repre sent parallel but potentially overlapping developmental trajectories.