Prevalence of chronic gastrointestinal symptoms in children with autism and autistic disorder.
Molloy CA, Manning-Courtney P
Autism 7(2): 165-171. 2003

Question: What is the rate of chronic digestive symptoms in children with autism?

Background: Many parents report that their children with autism suffer from stomach and bowel problems (gastrointestinal or GI problems). In the recent issue of the journal Autism, two researchers proposed that there is a higher than usual rate of GI symptoms in children with autism. They report on previous research on the topic of rates of bowel or stomach disorders in children with autism and propose theories about the nature of these conditions.

Participants: The charts of 139 children who had been diagnosed with either autism or an autism spectrum disorder between December 2000 and May 8, 2001 were audited.

Study Design: Chart audit. (Symptoms prevalence study)

Method: The charts of 139 children were examined for reports of stomach or intestinal problems. Of these children, information was available on 137. The symptoms the authors looked for were:

  1. Chronic diarrhea defined as loose, watery stools that last for three weeks in a row.

  2. Chronic constipation defined as fewer than 2 stools per week with difficulty passing the stools that last three weeks.

  3. Chronic vomiting or reflux, the latter defined as stomach contents which are propelled upward into the esophagus. The reflux had to have been documented by a test in which a narrow tube is passed into the esophagus with one end attached to a machine that documents the number of times over a 24-hour period that stomach contents go back up the esophagus, or by an x-ray that can show problems with the muscle that keeps the stomach closed and the stomach contents from backing up into the esophagus.

  4. Chronic pain in the abdomen or gaseousness, as reported by the parents.


Results: 24% of the children were found to have any stomach or intestinal symptom. The most frequently noted symptom was diarrhea (12.4% of all the children); the next most common was chronic constipation (8.8% of all the children).

Conclusions: The authors conclude that because the symptoms occur at a high rate in this population, but that the symptoms are not the same throughout the group, that this is evidence that several different ÒphenotypesÓ of autism and bowel disease exist, a phenotype being an outward, physical expression of the genes that the child carries. The authors did not find an association between these symptoms and reported regression.

Commentary

There is an idea that children with autism have a greater likelihood of having stomach and bowel problems that are believed by some to cause many of the symptoms of autism. It is certainly true that parents report that their children have diarrhea and/or constipation and that these symptoms are a real problem for the children and for their families. The children experience physical distress and the parents have the problem of maintaining their child's hygiene, but also the frustration and anguish of knowing their child is in pain. There is no doubt that the symptoms are real, but there is some question about whether these symptoms are specific to children with autism or whether the symptoms of autism are in some way worsened or even caused by the gastrointestinal (GI) disorders, or whether autism causes these symptoms.

This study looks at whether children with autism have high rates of bowel or stomach problems. The authors examined the charts of children with autism presenting to a specialist clinic to find reports of GI symptoms. This is an excellent first step because we need to know the rates of GI problems in children with autism. The authors didn't, however, compare the rates of digestive problems in children with autism to the rates found in children without autistic symptoms. We also need to know if the rates of GI problems in children with autism are higher than in children without autism.

The authors might also have looked at diagnosed disease, rather than at symptoms. Abdominal pain and gaseousness can be caused by many things other than bowel disease. Bloating can be caused by swallowing air; reflux can be caused by a problem with the muscle that holds the stomach closed or because of a hernia in the esophagus. Constipation and diarrhea are more usually caused by the foods eaten – lack of fibre, too much fibre, for example. It may be that the abnormal diet eaten by children with autism, in fact, causes these symptoms. Diarrhea and abdominal pain can also be caused by food intolerance related to lactose intolerance, which occurs very frequently in the general population. So the bottom line is that we need large scale research to follow on from studies such as this that provide promising clues to the origin of digestive problems in children with autism.

Patricia Colton, M.A., M.Ed.
CAIRN Project Coordinator