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A new long-term study has found that children diagnosed with autism are far more likely to experience ongoing gastrointestinal problems than their typically developing peers. The research also reveals that these stomach and digestive issues are linked to greater challenges with sleep, communication, sensory processing, and behavior. The findings were published in the scientific journal Autism.
Autism is a developmental condition that affects how a person communicates, interacts with others, and experiences the world around them. It is common for individuals with autism to show a preference for routines and engage in repetitive behaviors. It has long been observed that children with autism frequently experience other medical conditions, with gastrointestinal problems being among the most common complaints. While this connection is known, much less is understood about how these digestive issues progress throughout a child’s life.
Many previous studies that explored this link relied on reviewing past medical records, which may not capture a complete picture of a child’s day-to-day experience. Scientists at the University of California Davis MIND Institute sought to address this gap by following a group of children over several years.
They wanted to get a more direct and detailed view of the frequency and persistence of these symptoms. The researchers hypothesized that gastrointestinal symptoms would be both more common and more enduring in children with autism. They also predicted that this physical discomfort would be associated with greater challenges in other areas of development and behavior.
The investigation was a component of a larger, ongoing study called the Autism Phenome Project. It included 322 children diagnosed with autism and 153 typically developing children who served as a comparison group. Researchers collected information from the children and their families at three different points in time. The first assessment occurred when the children were between two and four years old. A second assessment took place two years later, and a final one happened during middle childhood, when the children were between nine and twelve years old.
At each visit, a developmental pediatrician who specializes in autism interviewed caregivers using a detailed questionnaire. This questionnaire asked about nine common gastrointestinal symptoms, including abdominal pain, gassiness or bloating, diarrhea, constipation, pain during bowel movements, and vomiting.
The researchers took specific steps to only include symptoms that did not have a known medical explanation. They excluded children from the gastrointestinal symptom group if their issues were explained by diagnosed conditions like celiac disease, chronic gastritis, or specific food allergies that were being managed. This allowed the team to focus on digestive problems without a clear underlying cause.
In addition to questions about digestive health, parents also completed a wide range of established questionnaires designed to evaluate their child’s cognitive abilities, social skills, repetitive behaviors, sensory sensitivities, sleep habits, and general emotional and behavioral well-being.
The results of the multi-year study confirmed the researchers’ initial expectations. Children with autism were about twice as likely to experience gastrointestinal symptoms at any given time point compared to their typically developing peers. The data showed that these problems were not only more common but also significantly more persistent in the autism group. While nearly two-thirds of the typically developing children never reported any of the nine targeted gastrointestinal symptoms across all visits, this was true for only about one-third of the children with autism.
The difference was even more apparent when looking at chronic issues. Among the children who participated in all three assessments, 30 percent of those with autism had gastrointestinal symptoms reported at every single visit. This rate of persistence was more than four times higher than the 7 percent observed in the typically developing group. Children with autism also tended to experience more digestive issues at the same time.
On average, they had about 2.4 more co-occurring symptoms, such as having both constipation and bloating, than children in the comparison group. The most frequently reported problems in both groups were constipation, diarrhea, gassiness, and abdominal pain, but these were all reported at higher rates for the children with autism.
The study also provided strong evidence for a connection between these physical symptoms and a child’s daily functioning. The analysis showed that, across both groups, the simple presence of gastrointestinal issues was associated with more significant challenges. Children with digestive problems, whether they had autism or not, tended to have more sleep difficulties, increased anxiety and depression, more complaints of physical discomfort, and greater sensitivity to sounds and sights.
When looking exclusively at the group of children with autism, the researchers found what could be described as a dose-response relationship. The more gastrointestinal symptoms a child experienced, the more pronounced their difficulties were across a broad spectrum of areas. An increasing number of digestive problems was directly linked to more intense repetitive behaviors, greater challenges with social communication, and heightened sensory sensitivities related to touch, taste, and smell. This pattern also extended to sleep, where a higher number of symptoms was associated with a wide array of disturbances, from breathing problems during sleep to significant daytime sleepiness and frequent night wakings.
The authors of the paper pointed out several limitations to their work. The information on digestive health relied on parent reports rather than direct medical examinations or lab tests. The study was also conducted at a single research center in California, which means the results may not be generalizable to all populations. Like many long-term studies, some families discontinued their participation over the years. The research team did analyze this and found that this attrition did not appear to significantly alter their main findings.
Despite these considerations, the study’s findings have important implications for clinicians, families, and researchers. The results highlight a clear need for doctors and parents to be aware of the high rate of persistent gastrointestinal problems in children with autism. The emergence of new behavioral challenges or the worsening of existing ones might be an outward sign of underlying physical pain or discomfort that a child cannot easily communicate.
The researchers suggest that screening for and effectively treating these digestive problems could lead to substantial improvements in a child’s overall well-being, daily functioning, and quality of life. Future research can build on these findings to explore the root causes of these gastrointestinal issues in the autistic population and to develop better ways to identify and support children who are most at risk for chronic digestive distress.
The study, “A longitudinal evaluation of gastrointestinal symptoms in children with autism spectrum disorder,” was authored by Bibiana Restrepo, Sandra L. Taylor, Matthew Dominic Ponzini, Kathleen Angkustsiri, Marjorie Solomon, Sally J. Rogers, Paul Ashwood, Daphne S. Say, Sonny Caceres, Shayan Alavynejad, Brianna Heath, David G. Amaral, and Christine Wu Nordahl.