FPG Project Summary

Pragmatic Skills of Children with Fragile X Syndrome, Down Syndrome, Autism Spectrum Disorder, and Typical Development

This study compares the developmental trajectories of pragmatic skills, the use of language in social contexts, among girls and boys with fragile X syndrome (FXS), Down syndrome (DS), and typical development (TD) and boys with autism spectrum disorder only (ASD-O) to determine whether individual differences in conversational discourse and narrative skills relate to FXS specifically or to either mental retardation (MR) or autism in general. The study will also compare potential mechanisms underlying these individual differences in pragmatic skills in FXS in comparison to DS and ASD-O. Study participants will be 80 boys with FXS (40 with and 40 without ASD) who are 6-12 years, 60 girls with FXS (30 6-12 years with MR and 30 3-6 years without MR), 40 girls and 40 boys with DS 6-12 years, 40 boys with ASD and MR 6-12 years, and 30 TD girls and 30 TD boys 3-6 years. All participants will have nonverbal mental ages between 3 and 6 years. Children’s pragmatic skills, including their initiations, contingency, perseveration, and repair strategies during conversation and their informativeness and cohesiveness during narration will be assessed annually for four years. Children’s language content and structure (receptive vocabulary and expressive syntax), cognition (nonverbal cognitive level and attention), social-emotional behavior (anxiety and autistic characteristics), and family environment (responsiveness and support of home environment and maternal contingency) will also be examined annually. In addition, Fragile X Mental Retardation Protein (FMRP) analysis from blood samples will be completed on the girls and boys with FXS, and activation ratios will be computed for the girls with FXS. Growth curve methods will be used to quantify patterns of change over time in the overall level and rate of growth in pragmatic development. Pragmatic skills are essential for effective communication and pragmatic difficulties can compromise all aspects of communicative competence in daily interactions.