Early Motor Trajectories in High-Risk Infants: A Case Study

Background: Early emerging motor skills are prerequisites for learning about the environment and for interacting with others (Gibson, 1988; Libertus & Hauf, 2017). Slow onset-patterns for key motor milestones have the potential to impact development across domains, especially communicative and language development (Zuccarini et al., 2018). Previous research has identified slower motor milestone achievement in high-risk (HR) infant siblings later diagnosed with Autism Spectrum Disorder (ASD). For example, HR infants later diagnosed with ASD show slower development of grasping behavior (Libertus, Sheperd, Ross, & Landa, 2014), and of sitting and standing skills (Nickel, Thatcher, Keller, Wozniak, & Iverson, 2013). Despite these findings, early motor development is not considered a diagnostic criterion for ASD (American Psychiatric Association, 2013) as motor delays are not specific to ASD (Ozonoff et al., 2008). However, motor delays may impact outcomes by impacting developmental cascades initiated by self-produced motor acts (Soska, Adolph, & Johnson, 2010). Therefore, more detailed research on the trajectories and developmental pathways of motor skills in infants later diagnosed with ASD is warranted.

Objectives: Examine the developmental trajectory of motor skill development during the first year using high-density sampling in HR infants with known outcome diagnoses.

Methods: Three HR infants participated in a longitudinal assessment of grasping behaviors over eight weeks starting at 3-months of age. Assessments were conducted in the family’s own home using video conferencing. At ten months of age, parents completed the Early Motor Questionnaire (EMQ) about their child. One HR infant received a subsequent diagnosis of ASD in a research setting (HR-ASD), one received a subsequent diagnosis of language delay in a community setting (HR-LD), and one received no diagnosis of developmental delays (HR-No). Three age and gender-matched typically developing infants (TD-matched) and to a larger sample of 40 TD infants (TD-GrandAv) served as comparison groups.

Results: Given the case study nature of the current HR sample, results are descriptive. Growth patterns show a prolonged (6 week) period of absent grasping-skill growth in HR-ASD and HR-LD infants, followed by a sudden “catch-up” burst. This contrasts with the HR-No and TD-Matched infants, who show gradually increasing motor-skill growth (see Figure 1). Parent-reported motor skills at ten months of age show low EMQ scores for HR-ASD and HR-LD infants, but not different from TD infants. A notable exception is the HR-No case, showing strong motor performance in all domains (see Figure 2).

Conclusions: The current study provides a detailed description of the developmental trajectory of grasping skills in HR infants with different outcomes. It appears that HR infants who go on to develop developmental delays show slower motor development followed by catch-up bursts in early infancy. By ten months of age, strong motor skills may be a protective factor for some HR infants – especially in the Perception-Action domain that measures skills such as hand-eye coordination. These findings suggest that unusual patterns of motor growth in HR infants could serve as early indicators for subsequent diagnoses of developmental delays. Implications and applications of the findings will be discussed.