The purpose of this pilot study was to examine (a) whether the application of PRT adapted for infants could increase the frequency of functional communication attempts made by infants at-risk for autism, and (b) whether a brief parent training intervention would teach parents how to elicit more frequent functional communication from their children. Results of this study demonstrate preliminary efficacy for a developmental adaptation of PRT to infants at-risk for an ASD. The PRT intervention resulted in gains in child functional communication and parent implementation of motivational procedures to elicit more frequent communication attempts from their children. This study makes a significant contribution to the search for evidence-based interventions appropriate for infants at-risk for ASD by providing preliminary evidence of the efficacy and acceptability of PRT in this population. Given the preliminary nature of this study, further research will be necessary to confirm the findings with larger numbers of children and stronger experimental controls. For instance, the small number of baseline probes across the three children limits the strength of experimental control for maturational changes and is an important limitation which will need to be addressed in future research. In spite of these limitations, this study is one of the first reports of the use of PRT procedures in children under 24 months of age (Schreibman et al. 2009
Though PRT has traditionally been applied with pre-school and school-age children, the results of this study demonstrate that the procedures can be adapted for use with very young children when the motivational principles are applied to elicit prelinguistic communication attempts so critical at this age (Osterling et al. 2002
). In this at-risk population, low frequency of functional communication, both verbal and nonverbal, is a significant concern (Boyd et al. 2010
; Rogers 2009
). Following the start of intervention, all three children demonstrated immediate increases in the use of functional communication both during intervention sessions and during probes taken of their parents independently using the procedures. The speed with which clinicians and parents were able to evoke these changes suggests that even a brief intervention applied early in development can rapidly increase a child’s opportunities to practice functional communication.
As a critical means of prelinguistic communication, gestures were a primary target of intervention and preliminary data regarding the types of communication used by children across probes indicated that all three children learned to use gestures regularly to communicate during treatment. Child 1 used gestures predominantly, while Child 2 and 3 often integrated multiple means of communication into a single bid. This integration represents a more advanced communicative skill and, given that integration of communication acts was not specifically targeted in intervention, this result suggests the possibility of an encouraging collateral gain which can be explored in future research.
Given the short duration of this intervention, it is quite promising that parents of infants at-risk for ASD were able to learn the principles of PRT procedures and reach or approach the 80 % level considered adequate for fidelity of implementation of PRT (Schreibman and Koegel 2005
). Prior research has suggested that parents can reach fidelity of implementation criteria following 25 h of parent training (Koegel et al. 2002
), therefore, implementation close to 80 % is considered good progress after only 10 h of training. These results provide evidence that the developmentally adapted procedures are easy for parents to learn and that parents can make substantial progress in learning skills for motivating their children to communicate even in a short period of time. Evidence of enhanced frequency of child communication when parents began implementing at least some PRT procedures appears to suggest that even partial implementation of PRT strategies may enhance child communication to some degree during parent–child interactions. For parents to consistently meet fidelity of implementation criteria, additional hours of parent training are likely to be needed. Additionally, parent reports of satisfaction with the parent education aspects of the intervention further support the use of a parent training approach and suggest that for parents who may be extremely worried about their at-risk infant, short-term parent training in strategies for eliciting functional communication may provide a constructive way to support their child’s social-communication development.
Examination of child functional communication during post-treatment probes indicated that Child 2 and Child 3 maintained their level of communication during interactions with parents once treatment had ended. However, particularly concerning are the data from Child 1 whose communication during the post-treatment probe, though higher than initial baseline levels, was relatively infrequent, occurring during only 12 % of intervals during the probe. For this child who demonstrated emerging symptoms of autism at 12 months, the brief nature of this intervention was effective in enhancing communication but not sufficient to address the severity of his social communication impairments. In this case, as is considered best-practice in the field, intensive early intervention programming appropriate for a child with autism is warranted as soon as a diagnosis of autism is suspected. Child 1 received referrals to local early intervention at 12 months of age, but due to a delay in the initiation of services by local providers, ultimately did not began services until after his participation in the study. Diagnostic outcomes at 36 months of age indicated that Child 1 continued to present with significant symptoms of autism at that age whereas Child 2 and Child 3, in spite of transient evidence of social communication impairment during the second year of life, did not meet criteria for a clinical diagnosis of autism at 36 months of age.
It is expected that infant siblings of children with ASD will have diverse outcomes and that some will develop ASD and some will not (Landa and Garrett-Mayer 2006
). The current study indicates that children with a variety of symptom presentations responded positively to the intervention. Future research will be needed to address the question of which children are likely to benefit most from this type of very early intervention and at what point in the development of a child at-risk for autism should intervention services be initiated. Based on the data from the current study, it is not possible to make conclusions about the effect of the brief intervention on subsequent observations of autism symptoms. However, it is possible that more intensive intervention provided over a longer period of time could significantly alter the developmental trajectories of these children at risk (Rogers 2009
) and further research will be needed to explore the extent to which intervention can alter the development of autism symptoms or the severity of impairment. Additionally, starting intervention even earlier, that is, within the first year of life, may provide even greater benefit in altering the developmental trajectory toward a more typical path. Given continued advances in early detection of autism symptoms (Ozonoff et al. 2010
) and increased monitoring of infant siblings of children with autism who are at risk for atypical social communication development (e.g., High Risk Baby Siblings Research Consortium), there is an urgent bioethical imperative to develop evidence-based interventions appropriate for this very young population.
Overall, this study provides promising preliminary data in support of the developmental application of PRT to target early functional communication skills in infant siblings at risk for ASD. This approach was well-accepted by families of these infants and provided parents with useful strategies for eliciting more frequent social communication and providing opportunities for the infant to practice meaningful reciprocal communication throughout daily routines at home. The initial efficacy of this line of research is supported and the results of this study constitute a first step toward investigating whether PRT can impact the trajectory of autism symptom development in infants at-risk. Additional research is now warranted to establish a more intensive program of intervention for these infants, and to track the lasting effects of a more intensive intervention on the developmental trajectories and condition of autism over time.