Wednesday, August 5, 2009

Study Watch : Incidence of Gastrointestinal Symptoms in Children With Autism

Photo by EyalNow (flickr)

In the August issues of Pediatrics there is a study that looks at how often gastrointestinal symptoms are seen in children with autism.

The authors looked at the medical records of children under 21 who had been patients of the Mayo Clinic between 1976 and 1997 -apparently this group covers 95% of the residents of Olmsed County, Minnesota - and identified the children who met the criteria DSM IV for autism.

There were a total of 124 children identified, 121 of which agreed to be included in this study. Each of these children were then matched with two control subjects (242) who were matched on gender, age, as well as other factors.

The charts of these groups were examined to find gastrointestinal symptoms and diagnoses in five categories :
  1. Constipation
  2. Diarrhea
  3. Abdominal bloating, discomfort or irritability
  4. Gastroesphageal reflux or vomiting
  5. Feeding issues or food selectivity
The data was then analyzed to determine if children with autism were more likely to have these symptoms or diagnoses. Out of the 121 children with autism, 87 had any reported problem on their charts while 167 of the 242 in the control group had issues.

The results show that children with autism were more likely to have constipation and feeding issues than typical children. There were not more likely to have diarrhea, abdominal bloating, reflux or vomiting and overall had the same incidence of symptoms.

The authors speculate that the constipation and feeding issues in the autism group are more likely to be related behavioral issues rather than any underlying biological reason. So the overall conclusion of the study is that children with autism are not more likely to have gastrointestinal symptoms.

This is a good study, as far as it goes. There is a lot of speculation and guessing in the study that is not supported by the data and there are some areas that I wish had been addressed better.

For example, the authors assert in the discussion section that children with autism are commonly treated with risperidone and that could potentially be responsible for constipation and selective eating. Yet I have to wonder why this wasn't included in the analysis or the data - they had access to the medical records of the children so they should have been able to determine if this was a factor or not.

Then there is the assumption that any gastrointestinal problem would be included in the medical records. The authors note this as a possible limitation of the study but dismiss this concern because children with autism are "subjected to increased medical scrutiny". I find this of line of reasoning very hard to shallow for a number of reasons but mostly because of my experiences with my own children.

My twin daughters had diarrhea, bloating and irritability, and feeding issues when they were infants before we placed them on a restricted diet. After being put on the diet they have food selectivity. We did talk to our children's doctor about these issues at the time yet our concerns were largely dismissed. I would be very surprised if there was any mention in their charts of these symptoms.

Mostly I wish that the authors had collected data on which of the children with autism are on restricted diets and whether that impacted the results. For example, were GI symptoms more common in children on a restricted diet or off?

But, as I said before, this is a decent study, if a bit limited. I certainly think that more research is needed in this area.

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