The significance of language regression in subtyping within the autism spectrum disorders
Jones, Lauren A.
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Individuals diagnosed with autism spectrum disorders (ASD) present with a wide range of heterogeneity; subtype validation therefore represents a major emphasis within this line of research. The published literature is reviewed, including subtype theory, past and present areas of ASD subtype research, and comparison of individuals with ASD with and without a history of language regression. Review conclusions indicate that while no one subtype solution explains all of autism variability, ASD likely exists on a continuum of developmental level and symptom severity on which exist overlapping subgroups that differ on severity level. Additionally, the validity of regressive autism as a subtype of ASD has not yet been determined and warrants continued attention. The purpose of the current study was to investigate the validity of ASD subclassification based on history of language regression. Participants (N =183 children, 2-17 years of age, diagnosed with an ASD) were divided into 4 groups on the basis of language history (i.e., delayed with regression, delayed with plateau, delayed without regression or plateau, and typical early language). Variable domains included adaptive behavior, symptom severity, and social-emotional functioning, which were measured using archival clinical assessment data. Multivariate analysis of variance and descriptive discriminant analysis were used to identify possible latent constructs that best explain group differences. A general trend of lesser symptom severity/better symptom-related adaptive functioning was noted for the typical vs. the delay groups, and better symptom-related adaptive behavior functioning for the plateau vs. the regression group. Groups formed on the basis of early language history may therefore exist on a continuum of level of pathology and prognosis, with individuals with more typical early language functioning better than those with a history of plateau or delayed/deviant language development, and individuals with plateau better functioning than those with a history of regression.