Rates of diarrhea, constipation, abdominal pain, and general gastrointestinal concerns appear to be higher in children with autism spectrum disorder compared with children without the disorder, according to a study released in Pediatrics today.
Gastrointestinal problems are frequently noted among children with autism spectrum disorder, the prevalence of which has increased substantially in recent years. Estimates from the US Centers for Disease Control and Prevention’s Autism and Developmental Disabilities Monitoring Network indicate that among 8-year-old American children, about 1 in 68 have a diagnosis of autism spectrum disorder.
In the new study, researchers from Emory University in Atlanta performed a meta-analysis of 15 studies on autism spectrum disorder and gastrointestinal symptoms from 1980 through 2012 and found that among a total pooled population of 2215 children, those with autism spectrum disorder had a greater than 3-fold prevalence of diarrhea and constipation, a greater than 2-fold prevalence of abdominal pain, and a greater than 5-fold prevalence of “general gastrointestinal concerns” compared with a control population. However, the study does not specify the actual rates of these symptoms in the autism spectrum disorder versus control populations, and therefore it is unclear what the absolute magnitudes of these differences are, which may affect the clinical importance of these findings.
This is the first quantitative study to support the expert consensus released in 2010 based on qualitative observations that there was a link between autism spectrum disorder and gastrointestinal symptoms.
Although these numbers may be useful for parents and pediatricians, the underlying reason for the increased rates of gastrointestinal symptoms remain unknown. The problem could be “functional;” that is, children with autism spectrum disorder may have behaviors such as suboptimal eating and toileting habits, such as extreme food selectivity (often a preference for starches and snack foods and an aversion towards fruits and vegetables) or ineffective toileting routines. Alternatively, the problem could be “organic,” that is, related to biological factors. Preliminary research has provided some support for such biological factors as an altered population of intestinal microbes, altered patterns of intestinal contractions, or increased risks of gluten sensitivity, lactose intolerance, food allergies, or gastroesophageal reflux disease in children with autism spectrum disorder.
The authors stated that this general topic of gastrointestinal disease in autism spectrum disorder has been understudied—perhaps because the gastrointestinal system was implicated as part of a causal pathway in the disease in a highly controversial and now-retracted study published in 1998 that suggested a potential link between autism and the measles-mumps-rubella (MMR) vaccine. The bottom line, they wrote, is that “additional research is needed to elucidate the etiology, prevalence, topography, and remediation” of gastrointestinal problems in autism spectrum disorder.