Gender and Comorbid Psychopathologies in Toddlers with Autism Spectrum Disorders A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at George Mason University

GENDER AND COMORBID PSYCHOPATHOLOGIES IN TODDLERS WITH AUTISM SPECTRUM DISORDERS Erica Buchholz, Ph.D. George Mason University, 2012 Dissertation Director: Dr. Johannes Rojahn Comorbid psychopathology, the co-existence of two or more disorders, often occurs in individuals with developmental disabilities. This study examined whether there were sex differences in five types of psychopathology in three groups of infants and toddlers: (1) a group with autism (n = 201), (2) a group with pervasive developmental disorder, not otherwise specified (PDD-NOS) (n = 254), and (3) a group at risk for developmental delays but without autism or PDD-NOS (n = 1146). The three groups were compared in a cross-sectional design at three ages: 12 to 24 months, 25 to 31 months, and 32 to 39 months of age. Five types of psychopathology (conduct/tantrum problem behaviors, inattention/impulsivity, anxiety, avoidance, and eating and sleeping problems) were assessed with the Baby and Infant Screen for Children with aUtIsm Traits (BISCUIT) – Part 2 for Infants and Toddlers. The major statistical analyses consisted of a factorial MANOVA and a factorial ANOVA. Results showed that children with autism were at the greatest risk for comorbid psychopathologies, followed by children with PDD-NOS, and then atypically developing children. Older children with autism were more strongly affected with comorbid symptoms than younger children with autism. Additionally, older children with PDD-NOS were more strongly affected by comorbid symptoms compared to younger children with PDD-NOS. No gender differences were found.