A preliminary epidemiologic study of social (pragmatic) communication disorder in the context of developmental language disorder

Background There is extremely limited population-based research on social (pragmatic) communication disorder (SCD). Population-based samples have the potential to better characterize the SCD phenotype by mitigating confounds and biases that are typical of convenience and clinical samples. Aims The aims of this preliminary epidemiologic study were to advance our understanding of the SCD phenotype relative to developmental language disorder (DLD), obtain an estimate of prevalence, identify risk factors and lay the groundwork for future population level research of SCD. Methods & Procedures We analysed existing data from the EpiSLI Database to examine social communication skills in 393 8th grade (13-14 years) children with and without a history of DLD. The primary measure used to evaluate SCD was the Children's Communication Checklist (CCC-2). Two case definitions of SCD reflecting DSM-5 criteria were examined. Both definitions involved significant pragmatic impairment, employing a commonly adopted clinical cut-point of 1.5 SD. In one case, pragmatic deficits could occur along with structural language deficits and, in the other case (established using principal component analysis), pragmatic and social skills were disproportionately lower than structural language abilities. Outcomes & Results When using the first case definition, SCD was much more common in children with a history of DLD than without DLD and history of language disorder at kindergarten was a significant risk factor for SCD in adolescence. However, it is important to note that SCD could be found in children with no prior deficits in other aspects of language. When the second definition was employed, SCD was equally distributed across children with and without a history of DLD. Male sex was a significant risk factor using this case definition of SCD. The estimated prevalence of SCD ranged from 7% (SE = 1.5%) to 11% (SE = 1.7%), acknowledging that prevalence depends on the cut-point selected to determine communication disorder. Conclusions & Implications These findings contribute to our understanding of the association between SCD and DLD by recognizing varying profiles of pragmatic and social communication difficulties, which in turn may help refine our diagnostic categories. Preliminary prevalence estimates of SCD can serve as an initial guidepost for identification and planning for intervention services for this condition. What this paper adds What is already known on this subject There is considerable debate about the diagnostic category of SCD and its relation to other neurodevelopmental disorders. What this study adds to existing knowledge Using data from a US-based epidemiologic sample of DLD, this study offers new information about the association between SCD and DLD, provides preliminary estimates of SCD prevalence, and identifies risk factors for SCD. Clinical implications of this study Improved understanding of possible profiles of pragmatic and social communication deficits will help to clarify diagnostic categories and preliminary prevalence estimates may assist with ensuring availability of adequate intervention services.