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.
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