Subgroups of children with autism by cluster analysis: A longitudinal examination

Objective: A hierarchical cluster analysis was conducted using a sample of 138 school-age children with autism. The objective was to examine (1) the c haracteristics of resulting subgroups, (2) the relationship of these subgro ups to subgroups of the same children determined at preschool age, and (3) preschool variables that best predicted school-age functioning. Method: Nin ety-five cases were analyzed. Results: Findings support the presence of 2 s ubgroups marked by different levels of social, language, and nonverbal abil ity, with the higher group showing essentially normal cognitive and behavio ral scores. The relationship of high- and low-functioning subgroup membersh ip to levels of functioning at preschool age was highly significant. Conclu sions: School-age functioning was strongly predicted by preschool cognitive functioning but was not strongly predicted by preschool social abnormality or severity of autistic symptoms. The differential outcome of the 2 groups shows that high IQ is necessary but not sufficient for optimal outcome in the presence of severe language impairment.