What Is the Relationship between Motor and Language Development and Joint Attention in Infants at High and Low Risk for ASD?

Background: Children with ASD and their younger brothers and sisters (high-risk (HR-)siblings) have a high risk of experiencing difficulties in language development. Research shows that both motor development and joint attention are important predictors for later language development. Since both markers may also influence each other, for example being able to sit makes it possible to show objects, it is important to look into the relationship of these three developmental domains in HR-siblings and in younger siblings of typically developing children (low-risk (LR-)siblings).

Objectives: The aim of the current study was to systematically investigate the relationship of early motor skills and joint attention on expressive and receptive language in HR- and LR-siblings during the first years of life.

Methods: HR-siblings (n = 35) and LR-siblings (n = 37) were followed during the first three years of life as part of a larger longitudinal study. Gross (GM) and fine motor (FM) skills were assessed at 10 and 14 months using the Mullen Scales of Early Learning (MSEL). Joint attention was measured using items (showing, initiating joint attention (IJA), response to joint attention (RJA)) of the Autism Diagnostic Observation Schedule (ADOS-2) at 14 months. Expressive (EL) and receptive language (RL) were measured by the MSEL at 24 months.

Results: HR-siblings had significantly lower scores on GM skills at 10 months (U = 383.00, p = .011) and on FM skills at 14 months (U = 355.00, p = .022). With regard to joint attention, HR-siblings presented a significantly lower quantity and quality of showing behaviors at 14 months. At 24 months HR-siblings had significantly lower scores on EL (U = 338.50, p = .027) but not on RL. In HR-siblings, EL at 24 months was correlated with GM skills at 10 months (ρ = .631, p = .00) and FM skills at 14 months (ρ = .546, p = .00). RL was correlated with GM skills at 10 (ρ = .598, p = .00) and 14 months (ρ = .436, p = .01), FM skills at 14 months (ρ = .608, p = .00) and IJA at 14 months (ρ = -.394, p = .03). On its turn, IJA at 14 months is correlated with FM skills at 10 months (ρ = -.440, p = .02). In LR-siblings, EL was only correlated with GM skills at 14 months (ρ = .358, p = .04), no correlations were found for RL.

Conclusions: Clear group differences were found for all three developmental domains, with HR-siblings scoring lower than LR-siblings. Correlational analyses showed more associations between these domains in HR-siblings, revealing different patterns in both groups. This indicates that early motor skills and joint attention may be more important in HR-siblings than in LR-siblings with regard to later language development. Implications will be discussed at the conference.