Early Intervention Improves the Flexibility and Focus of Visual Attention in Infants at High Risk for ASD

Background:  

Infants with older siblings with ASD have a 20% chance of developing ASD (Ozonoff et al., 2011) and are also at heightened risk for associated conditions such as ADHD. Testing the effects of early interventions that could prevent or ameliorate later symptoms requires sensitive biomarkers of the early mechanisms underlying symptom emergence. In this study, we report the effects of an early parent-mediated intervention program (modified Video Interaction to Promote Positive Parenting, mVIPP) on two features of visual attention. First, we examined the ability to shift attention between two stimuli, because slowed disengagement at 12 months is one of the most replicated neurocognitive features of early ASD (Jones et al., 2014).  Second, we examined saccadic reaction time variability (sRTV) to a peripheral stimulus. This variable is a robust endophenotype of behavioral-inattentive symptoms of ADHD that is sensitive to treatment (Tamm et al., 2012).

Objectives:  

To test whether mVIPP improves disengagement and reduces sRTV in infants with older siblings with ASD, and to assess how these changes relate to infant attentiveness in a naturalistic context (parent child interaction). 

Methods:  

Participants were n=54 infants with an older full sibling with ASD tested pre- (8 months) and post-intervention (14 months) on a battery of tasks. Between these visits, infants were randomized to receive intervention (n=28) or ‘treatment as usual’ (n=26 controls). The intervention program consisted of up to 12 therapist sessions over 5 months, plus daily parental practice.

Results:  

Tasks included a parent-child interaction, and an eye-tracker Gap task. Here, infants were presented with a central then a peripheral stimulus and saccadic reaction time (sRT) to visually fixate the peripheral stimulus was measured. The central stimulus either disappeared concurrently with the presentation of the peripheral stimulus (Baseline), 200ms earlier (Gap) or remained on screen throughout the trial (Overlap). Key dependent measures were a) the difference in sRT between Overlap and Baseline conditions (disengagement time); and b) the coefficient of variation in sRTs in the Baseline condition (sRTV). Parent child interaction was coded with the Manchester Assessment of Caregiver Interaction (e.g. Wan et al., 2012); the key variable was infant attentiveness.

Conclusions:  

Infants who received mVIPP showed a greater decrease in disengagement time than controls (suggesting improved attentional flexibility) and a reduced increase in sRTV between 8 and 14 months.  Individual differences in the increase in sRTV between 8 and 14 months were correlated with decreases in attentiveness measured during parent-child interaction. This is consistent with the proposal that sRTV may be a sensitive measure of early attention difficulties. Further analyses will explore relations to other biomarkers and behavioral changes in the same cohort.