Date of Completion


Embargo Period



Stephanie Milan, Ph.D.; Marie Coppola, Ph.D.

Field of Study



Master of Arts

Open Access

Open Access


Due to the elevated recurrence rates in high-risk younger siblings of children with ASD, the population is frequently used to examine early ASD symptomatology. However, the representative nature of this population compared to the general population of children with ASD is unknown. Previous research also suggests that parents of children with ASD raise concerns about the development of subsequent children earlier than first-time parents or parents of typically developing children. Whether an actual discrepancy exists in the attainment of milestones in these populations has not yet been assessed. The current study proposes to compare high- and low-risk children with ASD with respect to behavioral differences and milestone attainment. A high-risk sample of 23 children with ASD who had an older affected sibling was compared to 23 children with ASD drawn from a low-risk sample. Samples were matched on age, gender, and maternal education. T-tests and chi-squares were utilized to detect differences between groups on ASD symptomatology, cognitive ability, adaptive functioning, and milestone attainment. Few group differences on ASD symptom severity were observed. High-risk children had fewer communication-related symptoms than low-risk children, and significantly higher cognitive scores. Adaptive functioning and milestone attainment appeared similar across groups. High-risk children may be higher functioning than children drawn from the low-risk sample in their communicative skills and cognitive abilities. This may be partially related to high-risk parents' increased sensitivity to early signs of language and cognitive delay and may have implications for the generalizability of results from high-risk samples.

Major Advisor

Deborah Fein, Ph.D.