20219
Early Gross and Fine Motor Abilities in Infants at Heightened Vs. Low Risk for ASD: A Bsrc Study
Objectives: To examine GM and FM skills at an item level at 6 months in relation to outcome classification at 36 months in a large sample of HR and LR infants.
Methods: This study utilized data from the GM and FM subscales of the Mullen Scales of Early Learning (MSEL) administered at 6 months of age at 7 Baby Siblings Research Consortium (BSRC) sites. The total sample included 530 infants (363 HR, 167 LR). Thirty-six month outcome classification followed procedures outlined by Chawarska et al. (2014), with HR infants categorized as ASD, Atypically-Developing (ATYP), or Typically-Developing (HR-TD). A comparison sample of typically-developing low risk infants (LR-TD) was also included.
Results:
General linear mixed model logistic regressions with outcome classification and item as fixed effects and random intercepts for participants were carried out separately on the GM and FM subscale data (Figure 1). Results were generally similar across subscales, with group item performance for GM: (ASD=ATYP)<LR-TD (p<.01) and (ASD=ATYP)<HR-TD(p~.06); and for FM (ASD=ATYP)<LR-TD (p<.05,.01) and HR-TD<LR-TD (p<.01).
To examine motor milestones specific to age 6 months, we focused on subsets of 4 items on each subscale tapping sitting and grasping skills respectively and identified infants who were low performers (≥3 items failed; Figure 2).
For sitting items, significantly more ASD and ATYP infants were low performers relative to both the HR-TD and LR-TD groups, who did not differ from one another. A similar pattern of differences was evident for grasping items, but in addition, significantly more HR-TD infants fell into the low performing group relative to the LR-TD group (all ps < .05). Within the ASD group, significantly more females (44%) than males (22%) failed 3 or more grasping items (p = .04).
Conclusions: Delays in gross and fine motor development were evident among ASD infants at 6 months of age, but similar delays were also apparent among HR-ATYP infants. In addition, HR-TD infants also demonstrated delays relative to LR-TD infants in fine motor skills. These findings have implications for early identification and intervention efforts and for the
understanding of the pathways from genetic risk for ASD to social and cognitive impairments associated with ASD and the broader autism phenotype.