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Gastrointestinal disease and autism

 

Clinical bottom line

Children with autism have gastrointestinal disease no more frequently than children without autism.


Reference

C Black et al. Relation of childhood gastrointestinal disorders to autism: nested case-control study using data from the UK General Practice Research Database. British Medical Journal 2002 325: 419-421. (for full paper click here )

Study

The UK general practice research database (GPRD) is a well-known database where details of patients of selected GPs are available (anonymised) to researchers after consultation with an ethics review board.

This study examined all children born after 1987 and registered within six months of birth. Children with a diagnosis of autism in the 12 years to the end of 1999 were identified, and records obtained to demonstrate the correct diagnosis. Also identified were children with inflammatory bowel disease (ulcerative colitis, regional enteritis), chronic gastroenteritis, food intolerance and recurrent gastrointestinal symptoms at any time before the first recorded diagnosis of autism.

For each case of autism, five controls were selected, matched by birth date, sex, and doctor's practice. They were given an imaginary date of diagnosis of autism that was the same as for the case with which they were matched, and then treated in exactly the same way for ascertaining any prior gastrointestinal symptoms.

Results

There were 211,000 children, and 96 cases of autism (crudely 1 case in every 2,200). There were 449 controls. No child had Crohn's disease or ulcerative colitis. Gastrointestinal disorders before the date of diagnosis were found in 9% of the children with autism, and 9% of the children who acted as controls. There was no statistical difference. Most of the gastrointestinal disorders were cases of sympotoms of diarrhoea, colic, or vomiting within six months of one another, or food intolerance.

Comment

The link between bowel disease and autism has been that gastrointestinal disorders were evident before the diagnosis of autism. This appears not to be true.

A further claim was that first the gastrointestinal disorders, and then the autism, were cause by vaccination (either with measles vaccine, or MMR). This paper does not address that issue, but it effectively demolishes the theory on which the original claims of a link were made.