Prevalence of gastrointestinal symptoms among autistic individuals, with and without co-occurring intellectual disability

Gastrointestinal symptoms (GI) are very common among individuals on the autism spectrum. Prior research reports mixed findings regarding whether individuals with autism and co-occurring intellectual disability (ID) have elevated risk of gastrointestinal symptoms relative to individuals with autism alone. GI symptoms can be challenging to assess in individuals with autism spectrum disorder (ASD) and/or ID given challenges with language, communication, and interoception. Prior research has tended to only include individuals with documented presence or absence of GI symptoms or conditions, that is, to exclude observations in which there is uncertainty regarding presence of GI symptoms. Therefore, none of the prior autism studies reported the association between ID and the certainty regarding presence or absence of GI symptoms. The objective of this study was to examine differences in parental certainty and odds of reporting gastrointestinal signs and symptoms among children on the autism spectrum, with and without intellectual disability. Participants were 308 children (36% ID) with a clinical diagnosis of autism spectrum disorder (6-17 years). Parents endorsed whether their child had experienced or displayed a range of signs or symptoms related to GI problems in the past 3 months. Parents of autistic children with ID were less certain about the presence of more subjective symptoms, including abdominal pain, nausea, and bloating. Conversely, certainty regarding more objective signs (e.g., constipation, diarrhea, spitting up, etc.) was not significantly different. More accurate measures for GI signs/symptoms are needed for this population.