Defining and Quantifying Severity of Impairment in Autism Spectrum Disorders Across the Lifespan.

Abstract

Individuals with autism spectrum disorders (ASD) vary considerably in language level, cognitive ability, symptom severity, as well as comorbid psychopathology and behavioral issues. The first study in this three-paper project suggests preliminary means to stratify this diverse population into more homogeneous subgroups by ASD severity. Autism Diagnostic Observation Schedule (ADOS) scores were standardized within a large sample to approximate an autism severity metric. The resulting metric was less associated with verbal IQ than were ADOS raw totals, and resulted in increased comparability across age- and language-specific modules of this instrument. In the second study, standardized ADOS scores were used to plot longitudinal trajectories of ASD severity among children and adolescents. Four latent trajectory classes were identified, including persistent severe and persistent moderate groups, as well as much smaller classes that increased or decreased in ASD severity over time. Comorbid psychopathology is another way to characterize impairment in the autism spectrum. The third paper in this series posits that better understanding of the mechanisms that cause and/or maintain depressive symptoms in ASD will contribute to the ability to prevent and treat them, therefore providing one way to improve quality of life for these individuals. The objectives of this study were (1) to explore the relationship between insight into one’s own core autism symptoms and the level of depressive symptoms as described by the individual and an informant, and (2) to explore the relationship between social motivation, social participation, and level of depressive symptoms. Insight into functional independence impairments significantly predicted higher depression scores on the Beck Depression Inventory in the sample of adolescents and adults with borderline to above average IQ and ASD. This dissertation is thus focused on severity of impairment in autism spectrum disorders, with ‘impairment’ defined in relation to both autism-specific and comorbid factors.