Parent–infant interaction trajectories in infants with an elevated likelihood for autism in relation to 3-year clinical outcome

Developmental antecedents of autism may affect parent–infant interactions (PII), altering the context in which core social skills develop. While studies have identified differences in PII between infants with and without elevated likelihood (EL) for autism, samples have been small. Here, we examined whether previously reported differences are replicable. From a longitudinal study of 113 EL and 27 typical likelihood infants (TL), 6-min videotaped unstructured PII was blind rated at 8 and 14 months on eight interactional qualities. Autism outcome was assessed at 36 months. Linear mixed-effects models found higher parent sensitive responsiveness, nondirectiveness, and mutuality ratings in TL than EL infants with and without later autism. PII qualities at 8 (infant positive affect, parent directiveness) and 14 months (infant attentiveness to parent, mutuality) predicted 3-year autism. Attentiveness to parent decreased between 8 and 14 months in EL infants with later autism. This larger study supports previous findings of emerging alterations in PII in this group and extends on this by detecting earlier (8-month) predictive effects of PII for autism outcome and a more marked trajectory of decreased social attentiveness. The findings strengthen the evidence base to support the implementation of early preemptive interventions to support PII in infants with early autism signs.