The Social and Behavioral Phenotype of Children with Autism Spectrum Disorders and Comorbid Gastrointestinal Dysfunction

Background: The clinical manifestation of Autism Spectrum Disorder (ASD) is heterogeneous, with multiple medical and behavioral comorbidities of varying prevalence. Gastrointestinal dysfunction (GID) in ASD has been noted in multiple studies, but little information has been reported regarding differences in social functioning or behaviors associated with comorbid GID in children with ASDs. 

Objectives: The aim of this study is to characterize severity of autism symptoms, expressive language level, and social impairment in children with ASDs and comorbid GID, compared to children with ASDs without GID and to children without ASDs but with GID.

Methods: Children aged 5-18 years old were enrolled into one of three study groups: ASD and GID (+ASD/+GID), ASD without GID (+ASD/-GID), and no ASD but GID (-ASD/+GID). Children in the two +ASD groups were evaluated with the Autism Diagnostic Observation Schedule (ADOS). Children in the two +GID groups were evaluated by a gastroenterologist. Parents completed the Social Responsiveness Scale (SRS) for children in all three study groups. Enrollment of study participants is ongoing.

Results: Enrollment to-date is as follows: +ASD/+GID, n=39, mean age 11.7 years (SD=3.5), 77% male; +ASD/-GID, n=49, 12.2 years (3.7), 86% male; -ASD/+GID, n=29, 12.1 years (3.4), 45% male. ADOS classification (using revised scoring algorithms): +ASD/+GID, 95% autism, 5% autism spectrum; +ASD/-GID, 92% autism, 8% autism spectrum. A severity score of autism symptoms, based on ADOS score relative to age and language level, was not significantly different between ASD groups: +ASD/+GID mean score 7.9 (SD=1.7), +ASD/-GID mean score 8.0 (1.7), Independent Samples t-Test. Non-verbal children were significantly more prevalent in the +GID group: +ASD/+GID 31% non-verbal, +ASD/-GID 8% non-verbal, p=0.006 by Chi-Square Test. Stanford-Binet Abbreviated Battery IQ (ABIQ) scores were available for a subset of children, and showed no significant difference between groups: +ASD/+GID mean score 67.3 (n=13, SD=26.3), +ASD/-GID mean score 75.4 (n=27, SD=20.7), not significant by Independent Samples t-Test. SRS total T scores were significantly elevated in +ASD/+GID compared to +ASD/-GID and to -ASD/+GID children: +ASD/+GID mean score 90.8 (n=33, SD=13.2), +ASD/-GID 78.9 (n=30, SD=16.8), -ASD/+GID 51.0 (n=24, SD=12.3), p<0.01 by one-way ANOVA with Tukey HSD post hoc comparisons.

Conclusions: Parents report increased social impairment (based on SRS scores) in children with ASDs and comorbid GID, compared to children with ASDs but without GID. In our sample, children with ASDs and comorbid GID have lower expressive language skills compared to children without comorbid GID. For a subset of the children in this study, those with ASDs and comorbid GID do not show significantly different cognitive functioning compared to children with ASDs but without GID.