Doctor of Philosophy (PhD)



Document Type



The goal of this study was to systematically examine group differences among those with intellectual disabilities (ID) and comorbid Autism Spectrum Disorders (ASD) and epilepsy in an adult population through a detailed exploration of the characteristics that these disorders present in the areas of psychopathology, behavior problems, and impaired social behavior. Previous studies indicating that individuals with ID have comorbid ASD and neurological conditions tend to stop short of addressing these disorders’ impact on the full range of psychosocial issues, particularly in adult samples. Assessments of psychopathology, behavior problems, and impaired social behavior were made with the ASD-Comorbidity-Adult Version and ASD-Behavior Problems-Adult Version batteries and the Matson Evaluation of Social Skills for Individuals with Severe Retardation. One hundred participants with ID were matched and compared across four equal groups comprising 25 participants with ID, 25 participants with epilepsy, 25 participants with ASD, and 25 participants with combined ASD and epilepsy. When controlling for age, gender, race, level of ID, and hearing and visual impairments, significant differences were found for psychopathology (p < .05), behavior problems (p < .05), and social skills (p < .01). A direct discriminant function analysis was also conducted to determine whether certain subscales could predict group membership. Overall, 63% of the participants in the sample could be reliably distinguished between groups on these measures. These data conclusively demonstrated that individuals with ID expressing combined comorbid ASD and epilepsy were significantly more impaired than the control group (ID only) or groups containing only a single comorbid factor with ID (ASD or epilepsy only) on measures of psychopathology, behavior problems, and social skills. Implications of these findings elucidate the nature of these disorders and their influence on patient care and management.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Johnny L. Matson



Included in

Psychology Commons