Markers of Early Speech Development in Children At-Risk for Autism
Autism spectrum disorder (ASD) is a behaviorally defined and heterogeneous disorder. Biomarkers for ASD offer the opportunity to improve prediction, diagnosis, stratification by severity and subtype, monitoring over time and in response to interventions, and overall understanding of the underlying biology of this disorder. A variety of potential biomarkers, from the level of genes and proteins to network-level interactions, is currently being examined. Many of these biomarkers relate to inhibition, which is of particular interest because in many cases ASD is thought to be a disorder of imbalance between excitation and inhibition. Abnormalities in inhibition at the cellular level lead to emergent properties in networks of neurons. These properties take into account a more complete genetic and cellular background than findings at the level of individual genes or cells, and are able to be measured in live humans, offering additional potential as diagnostic biomarkers and predictors of behaviors. In this review we provide examples of how altered inhibition may inform the search for ASD biomarkers at multiple levels, from genes to cells to networks.
We sought to determine the potential effects of pooling on power, false positive rate (FPR), and bias of the estimated associations between hypothetical environmental exposures and dichotomous autism spectrum disorders (ASD) status. Simulated birth cohorts in which ASD outcome was assumed to have been ascertained with uncertainty were created. We investigated the impact on the power of the analysis (using logistic regression) to detect true associations with exposure (X₁) and the FPR for a non-causal correlate of exposure (X₂, r = 0.7) for a dichotomized ASD measure when the pool size, sample size, degree of measurement error variance in exposure, strength of the true association, and shape of the exposure-response curve varied. We found that there was minimal change (bias) in the measures of association for the main effect (X₁). There is some loss of power but there is less chance of detecting a false positive result for pooled compared to individual level models. The number of pools had more effect on the power and FPR than the overall sample size. This study supports the use of pooling to reduce laboratory costs while maintaining statistical efficiency in scenarios similar to the simulated prospective risk-enriched ASD cohort.
Keywords: autism spectrum disorders; measurement error; pooling.
This study examined vocal coordination during mother-infant interactions in the infant siblings (high risk infants; HR) of children with autism spectrum disorder (ASD), a population at heightened risk for developing language delays. Vocal coordination between mothers and HR infants was compared to a group of low risk (LR; no first- or second-degree relative with ASD) dyads, and used to predict later language development. Nine-month-old infants were videotaped at home playing with their mothers, and interactions were coded for the frequency and timing of vocalizations. Percent infant simultaneous speech was predictive of later language delay (LD), and dyads with LD infants were less coordinated with one another in average latency to respond than dyads with non-delayed (ND) infants. The degree of coordination between mothers and infants on this variable predicted a continuous measure of language development in the third year. This research underscores the importance of understanding early development in the context of interaction.
Keywords: Parent-infant interaction; coordination; high risk siblings; language development.
Early detection methods for autism spectrum disorder (ASD) in infancy are rapidly advancing, yet the development of interventions for infants under two years with or at-risk for ASD remains limited. In order to guide research and practice, this paper systematically reviewed studies investigating interventions for infants under 24 months with or at-risk for ASD. Nine studies were identified and evaluated for: (a) participants, (b) intervention approach (c) experimental design, and (d) outcomes. Studies that collected parent measures reported positive findings for parent acceptability, satisfaction, and improvement in parent implementation of treatment. Infant gains in social-communicative and developmental skills were observed following intervention in most of the reviewed studies, while comparisons with treatment-as-usual control groups elucidate the need for further research. These studies highlight the feasibility of very early intervention and provide preliminary evidence that intervention for at-risk infants may be beneficial for infants and parents.
The current paper provides an overview of an evidence-based treatment, Pivotal Response Treatment (PRT), for autism spectrum disorder (ASD). The paper describes PRT principles and then illustrates the approach using two case reports. The children are preschool-aged children with high-functioning ASD. They were participating in a four-month clinical trial of PRT. At the start of treatment, they presented with significant social communication impairments, including a minimal understanding of reciprocity, limited play skills, and repetitive behaviors and speech. The paper outlines how behavioral treatment goals were identified and then how activities were designed, using principles of PRT, to target skill acquisition. Following the treatment course, both children made substantial and meaningful gains in social communication skill development.
There is a growing literature on children with autism spectrum disorder (ASD) who respond favorably to behavioral treatment, which is often termed “optimal outcome.” Rates and definitions of optimal outcome vary widely. The current case series describes an empirically validated behavioral treatment approach called Pivotal Response Treatment (PRT). We present two preschool-aged children who received an intensive course of PRT and seem to be on a trajectory toward potential optimal outcome. Understanding response to treatment and predictors of response is crucial, not necessarily to predict who may succeed, but to individualize medicine and match children with customized treatment programs that will be best tailored to their unique and varied needs.
Keywords: autism; outcome; pivotal response treatment.