The Presence of Gastrointestinal Symptoms in Parents of Individuals with Autism Spectrum Disorder

Background: Gastrointestinal (GI) symptoms are four times as common in ASD than controls (McElhanon, 2014), and may exacerbate the behavioral and psychosocial symptoms of the disorder (Mazurek, et al. 2013; Maenner et al. 2012; Peters et al. 2014). However, it is unclear how GI symptoms relate to the underlying causes of ASD. Evidence suggests an association between GI symptoms and ASD candidate genes (Campbell et al., 2006; Bernier et al., 2014), and family studies show aberrations in intestinal bacteria in siblings (Finegold et al., 2010; Gondalia et al., 2012; Parracho et al., 2005). This study built on previous work by examining the presence of GI symptoms in both individuals with ASD and their parents.

Objectives: To examine the familiality of GI symptoms in ASD by investigating the rate of symptoms in individuals with ASD and their parents, and how such features may relate to behavioral and psychosocial features. 

Methods: Seventeen individuals with ASD and 35 parents (22 mothers, 13 fathers) were administered a battery of questionnaires to characterize a range of GI symptoms associated with functional or organic disorders of the digestive system. Functional disorders (FGID) include those that cannot be explained by structural or tissue abnormality (e.g., Irritable Bowel Syndrome, IBS) while organic disorders have known, physical, etiology (e.g., Crohn’s Disease). GI symptoms were examined in relationship to previously collected phenotypic assessments of depression, anxiety, executive functioning, sensory sensitivity, pragmatic language, and social cognition.  

Results: Forty three percent of individuals with ASD and more than half (63%) of parents met criteria for a GI disorder. While epidemiological studies have not been conducted to establish population based rates, this is substantially higher than 10-20% prevalence rates reported for IBS (the most common of FGIDs) in the general population. Higher rates of pragmatic language differences were noted among both individuals with ASD (p=.07) and parents (p<.05) who met criteria for a GI disorder, compared to those without a GI disorder. Parents who met criteria for a GI disorder also demonstrated greater sensory sensitivity, a higher likelihood of generalized anxiety disorder, and stronger social cognitive abilities (p’s < .05) relative to ASD parents without GI disorders. Parents with a GI disorder were significantly more likely to have children with a GI disorder (p<.05). 

Conclusions: Results document a high prevalence of GI disorders in individuals with ASD as well as their parents, suggesting studying GI symptomatology may help further our understanding of the complex etiology of ASD.  The relationship between pragmatic language deficits and GI disorders is consistent with prior studies in ASD and adds to our understanding of underlying causes of ASD from a familial perspective. The presence of GI symptoms in parents corresponds with important behavioral and psychosocial profiles, complementing prior studies documenting relationships between GI symptoms and features of ASD in probands. This study contributes to a growing body of research supporting evidence of the gut-brain connection in ASD (Hsiao, 2013).