Association of Social Skill Deficits and Autism Symptomology in Boys with Fragile x Syndrome

Background: Boys with fragile X syndrome (FXS) are at high risk for developing autism spectrum disorders (ASD) (Brock & Hatton, 2010). Social skill deficits are a key symptom of ASD that play an important role in preschoolers’ academic, social, and psychological outcomes (Frey, Elliot, & Gresham, 2011; Gillis, Callahan, & Romanczyk, 2011). Social deficits are well documented in FXS, although many studies have not accounted for the impact of ASD comorbidity and it is unclear whether such deficits are characteristic of ASD within the context of FXS rather than of FXS itself. 

Objectives:   This study compared social skill deficits in preschool boys with only FXS (FXS-O), FXS+ASD, and TD, to examine the impact of ASD comorbidity on the social profiles of children with FXS.  

Methods:  Participants included boys with FXS-O (n=32), FXS+ASD (n=21) and typical development (TD; n=22) ranging from 36-60 months of age (M=46.61, SD=6.51). Parent report of children’s social skills was obtained using the preschool version of the Social Skills Rating System (SSRS; Gresham & Elliot, 1990). The SSRS is a standardized questionnaire that measures the perceived frequency with which social skills are displayed in the home and the community.  The SSRS consists of 4 subscales: Cooperation, Assertion, Responsibility, and Self-Control and a total standard score. The total standard score and the subscale raw scores were used in this study. Autism symptoms were assessed with the Childhood Autism Rating Scale (CARS; Schopler et al., 1988). The CARS consists of 15 items rated on a scale of 1 to 4, with a total score of 30 or above consistent with a diagnosis of ASD; ASD-status of the boys with FXS was determined with the CARS.   

Results: A MANOVA indicated a significant effect of group on the SSRS total score (F(2,72)=78.65, p<0.05)and on all of the subscales: Cooperation (F(2,72)=44.389, p<0.05), Assertive (F(2,72)=40.98, p<0.05), Responsibility (F(2,72)=32.22, p<0.05), and Self-Control (F(2,72)=57.38, p<0.05). Bonferroni-corrected pairwise comparisons showed that the boys with FXS+ASD had significantly less competent social skills than those with FXS-O (p<0.05) across all scores.  Both groups with FXS, regardless of ASD-status, displayed less competent social skills than their TD peers (ps<0.05) across all scores.  The boys with FXS+ASD performed significantly worse than both other groups (p<.05) across all scores. The boys with FXS-O also performed worse than the TD boys, but significantly better than the boys with FXS-ASD (p<.05).

Conclusions: Findings suggest that social deficits may be an area of concern for those with FXS-O, but even more so for those with FXS+ASD. Furthermore, ASD comorbidity contributes to social skill deficits in young children with FXS but does not account for such deficits entirely.