Though previous case reports have suggested a link between autism and celiac disease, larger studies have shown contradictory results. And now, one of the largest studies of the two conditions found no association between them.
Researchers from the Karolinska Institutet in Sweden published the results of their study in JAMA Psychiatry.
Dr. Jonas F. Ludvigsson led the study, in which a Swedish national patient register was used to find patients with autism spectrum disorders (ASDs). The team also used 28 Swedish biopsy registers to find data about patients with celiac disease (CD).
In total, there were 26,995 patients with CD, 12,304 patients with inflammation of the small intestine, and 3,719 patients with normal mucosa but a positive CD blood test. These groups were compared with a control group of 213,208 individuals.
Results showed that having a diagnosis of ASD was not associated with CD or inflammation. However, an ASD diagnosis was linked to an increased risk of having normal mucosa but a positive antibody test frequently seen with CD.
The researchers say:
"Our data are consistent with earlier research in that we found no convincing evidence that CD is associated with ASD except for a small excess risk noted after CD diagnosis."
Although the researchers note that "the mechanism of association with a positive CD antibody is not clear," they do suggest it could be attributed to "increased mucosal permeability" in some CD patients or in certain individuals with elevated antibody levels.
Autism and intestinal permeability
Autism spectrum disorders, which include infantile autism, Asperger syndrome and pervasive development disorders, are typically noticeable before the age of 3.
Researchers found autism was not associated with celiac disease, which is accompanied by sensitivity to wheat and gluten found in foods like bread.
The researchers note that celiac disease is an immune disorder occurring in 1-2% of the Western population. Triggered by gluten exposure, CD normally affects patients who have small intestinal villous atrophy and inflammation.
However, the researchers say that recently, there has been evidence that some people with CD have only minor mucosal changes, if any at all.
In an interview with Medical News Today, Dr. Ludvigsson said that "the link to individuals with normal mucosa and increased celiac antibodies is intriguing."
He offered three potential explanations for the link:
- Different testing of children with autism (meaning autistic patients undergo more testing for celiac disease than other individuals, rendering the association false)
- Researchers could find results "just by chance"
- Individuals with autism could have a different intestinal permeability, explaining the association between autism and those with normal mucosa but increased celiac antibodies.
He clarified his last point by noting:
"I think it is reasonable to examine intestinal permeability of patients with autism, but I do not think that celiac disease causes autism."