Neonatal and Early Infant Developmental Profiles of High-Risk Siblings of Children with ASD

Background: In an effort to improve early identification of ASD, prospective longitudinal studies of infant siblings of children with ASD have delineated early development profiles of high-risk infants. These profiles characterize infant development from 12-36 and even 6-36 months of age, identifying cognitive, motor, and language deficits for infants who go on to develop ASD (e.g., Barbaro and Dissanayake, 2012; Landa et al., 2012). Yet, little to no research has examined developmental profiles of high-risk infants in the neonatal and early infant period, from birth to 6 months. An understanding of key developmental differences during this early period, including neurological functioning and cognitive and motor development, will contribute to a mechanistic understanding of the emergence of ASD, ultimately leading to the development of targeted interventions.

Objectives: The current study examines neonatal neurobehavioral functioning and subsequent longitudinal developmental profiles from birth to 6 months of age for high-risk infant siblings of children with ASD (HR) compared to low-risk infant siblings of typically developing children (LR).

Methods: In a prospective, longitudinal design, HR (N=51) and LR (N=49) infants were administered the NICU Network Neurobehavioral Scales (NNNS) at 1-month and the Bayley Scales of Infant and Toddler Development (Bayley) at monthly intervals between 1 week and 6 months of age. Neurobehavioral functioning at 1 month of age was compared between HR and LR infants using independent sample t-tests. Specifically, measures of attention, regulation, arousal, excitability, and lethargy were examined. Linear mixed models were then used to examine trajectories of cognitive, fine motor, and gross motor development between 1-6 months across HR and LR infants.

Results: Neonatal neurobehavioral functioning was largely comparable across the groups, with the exception of regulation for which LR infants outperformed HR infants (t(65) = -2.70 , p = < .01). Linear mixed models indicated a significant main effect of risk for trajectories of cognitive development (F(1,341)=3.98, p<.05) and a marginally significant main effect of risk for trajectories of fine motor skills (F(1,338)=3.80, p=.052). Gross motor development was not different between HR and LR groups (F(1,338)=0.05, p=.829).

Conclusions: These findings suggest that that infants who are at an increased genetic risk for developing ASD may experience very early developmental vulnerabilities, present as early as 1 month of age, prior to the emergence of social-communication deficits. Regulation abilities, which refer to the capacity to organize motor activity and physiological reactivity, were found to be significantly lower for 1-month-old HR infants. Subsequently, HR infants were found to achieve cognitive and fine motor milestones later than LR infants through the first 6 months of life. Additional research is needed to investigate the possibility that lower regulation abilities contribute to these later delays. Indeed, regulation capacities afford increased opportunity for controlled, organized exploration of the environment, which may foster the emergence and refinement of cognitive and fine motor skills. Overall, this research highlights very early vulnerabilities, possibly grounded in disrupted neurological functioning from birth, that should be further investigated as biomarkers of later-emerging social-communication deficits.