The authors of the study hypothesized that perhaps:
The head trauma released an enzyme, transglutaminase TG6, which set-up a reaction of the immune system against it, which then bled over to cause a reaction like celiac disease. TG6 is very similar to TG2, an antigen that's recognized in celiac disease patients.
The head trauma is what led the patient to seek medical attention initially, and that visit increased the likelihood of a diagnosis of celiac diagnosis.
Since celiac disease can affect balance, these patients had an increased likelihood of a fall that could cause head trauma. That being said, the causes of the head trauma were not identified for this study and would have to be considered as part of a future study.
Dr. Murray is a Mayo Clinic gastroenterologist and celiac disease expert.