Prevalence and Clinical Characteristics of Social (Pragmatic) Communication Disorder in a Clinic-Referred Sample

Background: Social (pragmatic) communication disorder (SCD) was only recently added to psychiatric nosology with the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Since it is a relatively new diagnosis, little is known about the clinical characteristics of those that receive it or how its symptomatology compares to that of autism spectrum disorder (ASD). SCD has been conceptualized as a milder form of ASD; an impairment in social communication in the absence of restricted and repetitive behaviors. Although there is evidence to support this characterization, the only studies to investigate the prevalence and characteristics of SCD have mapped data retrospectively on to the DSM-5 criteria. This is problematic because symptom definitions were expanded from the fourth (DSM-IV-TR) to the fifth edition of the DSM; therefore, clinicians using the DSM-IV-TR may not have fully assessed for symptoms in the DSM-5.

Objectives: The study objectives were to: (1) prospectively examine the prevalence of SCD in a sample of children referred for ASD evaluation, (2) describe the clinical characteristics of children with SCD, and (3) compare the characteristics of children with SCD to those of children with ASD and children with other diagnoses (clinic-referred comparison, CC).

Methods: Participants included 438 children and adolescents (2-17 years) referred for clinical evaluation for ASD who received diagnostic evaluations at one of six Autism Treatment Network sites. Assessments included review of records, diagnostic interview, Autism Diagnostic Observation Schedule-2^ndEdition (ADOS-2), cognitive assessment, assessment of behavioral functioning (including Child Behavior Checklist, CBCL), and final determination of all relevant DSM-5 diagnoses.

Results: The prevalence of SCD was 1.4% (n = 6). Five males and 1 female received SCD diagnoses with a large range in both age (3-17) and IQ (86-115). For SCD cases, ADOS-2 Calibrated Severity Score (CSS) ranged from 1-7 (mean = 3.7), ADOS-2 Social Affect (SA) ranged from 1-9 (mean = 4.5), and ADOS-2 Repetitive Behavior (RRB) ranged from 1-7 (mean = 4.5). Mean ADOS-2 CSS, SA, and RRB scores were lower for the SCD than the ASD group (CSS = 7.3±1.9, SA = 7.3±1.9, RRB = 7.3±2.1), but higher for the SCD than the CC group (CSS = 2.9±1.9, SA = 3.5±2, RRB = 4±2.7). Mean CBCL Total, Internalizing, and Externalizing scores were lower for SCD cases than ASD and CC groups; however, range in the SCD group was large (e.g., 31-74 for Total score). Four SCD cases (66.7%) also met criteria for DSM-5 attention-deficit/hyperactivity disorder; three SCD cases (50%) also met criteria for DSM-5 generalized anxiety disorder.

Conclusions: This was the first large-scale prospective study to examine the prevalence and characteristics of SCD diagnoses in a clinically-referred population. The results indicate that SCD diagnoses were rarely made across multiple sites and clinicians. Due to the small number of cases in this sample, it is difficult to make conclusions about clinical characteristics as a whole; however, it is notable that children and adolescents receiving SCD diagnoses demonstrated significant heterogeneity in terms of ASD symptomatology, cognitive functioning, and psychiatric comorbidity.