Direct and Indirect Effects of Behavioral Parent Training on Infant Language Production

Given the strong association between early behavior problems and language impairment, we examined the effect of a brief home-based adaptation of Parent-child Interaction Therapy on infant language production. Sixty infants (55% male; mean age 13.47±1.31 months) were recruited at a large urban primary care clinic and were included if their scores exceeded the 75th percentile on a brief screener of early behavior problems. Families were randomly assigned to receive the home-based parenting intervention or standard pediatric primary care. The observed number of infant total (i.e., token) and different (i.e., type) utterances spoken during an observation of an infant-led play and a parent-report measure of infant externalizing behavior problems were examined at pre- and post-intervention and at 3- and 6-month follow-ups. Infants receiving the intervention demonstrated a significantly higher number of observed different and total utterances at the 6-month follow-up compared to infants in standard care. Furthermore, there was an indirect effect of the intervention on infant language production, such that the intervention led to decreases in infant externalizing behavior problems from pre- to post-intervention, which, in turn, led to increases in infant different utterances at the 3- and 6-month follow-ups and total utterances at the 6-month follow-up. Results provide initial evidence for the effect of this brief and home-based intervention on infant language production, including the indirect effect of the intervention on infant language through improvements in infant behavior, highlighting the importance of targeting behavior problems in early intervention.