Objectives: The primary aim of the current study is to examine the disengagement operation and its associations with 1) putative neural circuits and 2) repetitive behavior measured at 12 months of age in a large cohort of high-risk infant siblings of children with autism and low-risk typically developing infants. We hypothesize that genetic liability for autism will moderate the relationship between both disengagement and repetitive manipulation of objects and the relationship between disengagement and indices of white matter fiber development of the splenium.
Methods: The final sample will include approximately 40 low-risk and 100 high-risk infants who have eye tracking data, behavioral data, and brain imaging data at 12 months of age. The sample includes participants recruited and assessed at the UNC, CHOP, and WashU clinical sites of IBIS. The modified gap/overlap paradigm is designed to examine the disengagement operation and is administered using Tobii eye-tracking equipment at each site. The Repetitive and Stereotyped Movement Scales (RSMS), a coding scheme developed as a companion to the behavioral sample of the Communication and Symbolic Behavior Scales (CSBS), is used to extract stereotyped motor behaviors and repetitive manipulation of objects. Finally, as part of an imaging protocol that includes structural MRI and resting BOLD, the 25 direction DTI sequence yields diffusion images that allow for analysis of diffusion properties and fiber tracking.
Results: Preliminary analyses indicate group differences in repetitive behavior at 12 months as measured by the RSMS (p < 0.05), suggesting a greater prevalence of ‘repetitive manipulation of object’ behaviors in the genetically high-risk group (HR, n=40; LR, n=20). Preliminary analyses of the disengagement operation indicate no differences (p > 0.05) between high-risk (n=36) and low-risk (n=25) infants. Analyses between the disengagement operation and white matter fiber integrity of the splenium are ongoing.
Conclusions: Repetitive behaviors appear to be more prevalent among high-risk infants than low-risk infants and thus may be endophenotypic marker of the disorder. Future examinations promise to explicate the role of attention disengagement in the early development of repetitive behaviors. Additionally, no published data to date has examined associations between white matter fiber integrity and cognitive performance in this age range. Collectively, this study will directly inform future analyses of the longitudinal outcome data and may point to putative neural markers important in the pathogenesis of autism.
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