Past case studies have suggested a link between celiac disease and autism spectrum disorder (ASD), but studies have contradicted that finding.

Swedish researchers found no link between the two disorders, they looked at 26,995 people with celiac disease (CD), 12,304 people with inflammation of the intestines, and 3,719 people without the usual symptoms but who had tested positive for CD, a Karolinska Institutet news release reported. The team also included data from a control group of 213,208 individuals.

Celiac disease is thought to occur "when the body's immune system overreacts to gluten in food," but the exact cause is unknown, MayoClinic reported.

The study concluded that those who had been diagnosed with ASD were at no higher of a risk for CD than those who did not suffer from the condition. The researchers did find that people who had been diagnosed with ASD were more likely to show no damage to the intestinal mucosa (a common sign of CD) but to have a positive antibody test, the news release reported.

"The researchers note that the mechanism of association with a positive CD antibody is not clear, and speculate that the association could be due to increased mucosal permeability in some patients with CD or in individuals with elevated levels of some antibodies," the new release stated.

The researchers believe there could be another explanation for the previously-made link between the two conditions.

"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. We can't rule out the fact that children with ASD are investigated for CD more often than others, which could explain these results", study author Jonas Ludvigsson, a Professor at Karolinska Institutet, said.

CD is considered to be an immune disorder that comes with gastrointestinal symptoms. It eventually causes the immune system to destroy villi in the small intestine, which prevents the body from absorbing nutrients.