Quality of Interaction Between At-Risk Infants and Caregiver At 12-15 Months Is Associated with 3-Year Autism Outcome

Background:  Recent models of the early emergence of autism spectrum disorder (ASD) propose that infant intrinsic risk susceptibilities in behaviour may be amplified by interaction within the early social environment into an increasingly atypical developmental trajectory. A few studies have examined prospectively parent-infant interaction in infants who have an older sibling with ASD (‘at-risk siblings’) and found specific differences from those in low-risk controls, but studies have involved small samples, findings have been inconsistent and there has been little follow-up to later ASD outcome.

Objectives: This study examined whether 6- and 12-month parent-infant interactions in at-risk siblings differ from those with low-risk, and whether – in at-risk siblings – such interactions predict later 3-year classification of ASD, or no ASD.

Methods: Within the British Autism Study of Infant Siblings (BASIS), 6-min videotaped episodes of parent-infant free play in infants at 6-10 months ('6 months': 45 at-risk siblings, 47 low-risk siblings) and 12-15 months ('12 months': 43 at-risk siblings, 48 low-risk siblings) in a laboratory setting were rated on the Social Interaction Measure for Parents and Infants (SIM-PI), blind to participant information. Standard tests were administered for concurrent behavioural signs of ASD features and developmental level. Systematic consensus diagnostic classification of ASD was made at 3 years for the at-risk siblings.

Results: Parent non-directiveness and sensitive responsiveness differed in relation to ASD/risk status (at-risk ASD, at-risk no-ASD, low-risk) at both 6 and 12 months. At 6 months, infant liveliness was lower in the high-risk groups; at 12 months, infant attentiveness to parent and positive affect were lower in the at-risk group later diagnosed with ASD. Dyadic mutuality and intensity of engagement showed a group effect at 12 months. Dyadic mutuality, infant positive affect, and infant attentiveness to parent at 12 months (but not 6 months) predicted 3-year ASD outcome, whereas infant ASD-related behavioural atypicality did not.

Conclusions: This is the first prospective evidence that early dyadic interaction between at-risk infants and their parents is associated with later diagnostic outcome in ASD. Possible explanations for these findings and their theoretical implications are considered.