Abstract
There is a wide range of variability in symptoms and comorbid behaviors among individuals with Autism Spectrum Disorder (ASD). Variability is seen both between individuals at a given point in time and in patterns of change within individuals over time. The goals of the current study were to examine (1) initial levels and rates of change in social reciprocity and internalizing and externalizing behavior problems, and (2) the effects of initial temperament, verbal IQ, and symptom severity on mean initial levels and rates of change in social reciprocity and comorbid internalizing and externalizing behaviors. The sample consisted of higher functioning children with autism (HFA) and an age- and gender- matched non-ASD comparison sample (non-ASD), 8-19 years old. One fifty four adolescents (80 HFA, 74 non-ASD) and their parents participated in a series of visits, in which temperament, autism symptoms, and comorbid internalizing and externalizing problems were assessed. Using multilevel modeling (MLM) in HLM6 results indicated that all children decreased in internalizing behaviors and social reciprocity over childhood and adolescence. Externalizing behaviors showed trend level improvements for both adolescents diagnosed with HFA and non-ASD adolescents. In general, higher levels of negative affect, lower levels of effortful control (EC), and lower levels of surgency were associated with concurrent maladjustment in internalizing, externalizing, and ASD symptom related problems, such as social reciprocity. Lower levels of negative affect and higher verbal IQ were associated with greater reductions in emotional, behavioral, and social reciprocity problems across critical adolescent years. Importantly, these predictors and their relations to patterns of development were generally consistent for both adolescents diagnosed with HFA and non-ASD adolescence, emphasizing a generalized effect of temperament on behavior change, regardless of a diagnosis. Results suggest the importance of assessing and acknowledging temperament to inform targeted intervention and goodness-of-fit for both children with HFA and non-ASD children.