Interactions between Language and Behavioral Development in Toddlers at High-Likelihood for Developmental Language Disorder

Abstract

Rationale: Children with developmental language disorder (DLD) often have co-occurring behavioral challenges, including internalizing and externalizing problems. Despite this known overlap, few studies have examined the developmental trajectories of language and behavior together, or tested whether early language interventions impact behavioral outcomes in toddlers at high-likelihood for DLD. Method: This dissertation used longitudinal data from a multisite randomized controlled trial with 105 toddlers at high risk for DLD. Participants were randomized to receive either Enhanced Milieu Teaching-Sentence Focus (EMT-SF), a caregiver-mediated naturalistic developmental behavioral intervention, or business-as-usual services. Language skills (i.e., mean length of utterance in words [MLUw], intelligibility) and behavioral challenges (i.e., temper loss, internalizing behaviors) were assessed from 30 to 49 months of age. Bivariate latent change score models were used to examine the developmental trajectories and associations between language skills and behavior challenges. Multiple regression analyses were used to evaluate language intervention effects on behavioral outcomes at age 4. Results: Children demonstrated growth in language skills and reductions in temper loss over time. Gains in MLUw were modestly linked to decreases in temper loss between 36 and 42 months, suggesting a potential relation during that period. No significant associations were found between changes in intelligibility and temper loss, and the EMT-SF language intervention did not affect internalizing or externalizing behaviors at post-test. Conclusion: This study provides new evidence on the complex associations between language and behavioral development in young children at high risk for DLD. Findings suggest that associations between changes in MLUw and temper loss may occur during specific time periods. However, the EMT-SF intervention did not significantly impact behavioral challenges at post-test. Continued research to identify additional measures and clarify potential mechanisms underlying these complex associations is needed.