Celiac disease is a risk factor for schizophrenia

People with a history of the digestive disorder celiac disease are three times more likely to develop schizophrenia than those without the disease, according to a report by Danish researchers and a researcher at the Johns Hopkins Bloomberg School of Public Health. The report is published in the February 21, 2004, edition of the British Medical Journal.

Celiac disease is an autoimmune disorder that impairs the body's ability to digest the protein gluten, which is found in grains and many other foods. The condition can lead to diarrhea, weight loss and malnutrition. William W. Eaton, PhD, lead author of the report and interim chair of the Department of Mental Health at the School of Public Health, said, "For years, scientists have suspected a link between celiac disease and schizophrenia. Our research shows that the link is moderately strong."

Dr. Eaton and his colleagues examined the records of 7,997 schizophrenic patients admitted to a Danish psychiatric facility for the first time between 1981 and 1998. Those records were compared to Denmark's national patient register to determine if the schizophrenic patients or their parents were previously treated for celiac disease. The researchers also looked for diagnosis of similar digestive disorders not previously associated with schizophrenia, which included dermatitis herpetiformis, Crohn's disease and ulcerative colitis.

The researchers found a small number of schizophrenic patients were previously treated for celiac disease or had a parent treated for celiac disease. Both conditions are rare. The prevalence of celiac disease among schizophrenics was 1.5 cases per 1,000 compared to 0.5 cases per 1,000 in the larger control group. After adjusting for other factors associated with schizophrenia, the researchers determined that the risk of schizophrenia was three times greater with a history of celiac disease. Crohn's disease and ulcerative colitis were not associated with an increased risk of schizophrenia.

"More research is needed to understand the link between celiac disease and schizophrenia. The most important question is whether treatment for celiac disease, in the form of a gluten-free diet, would benefit the small proportion of individuals with schizophrenia who are genetically prone to celiac disease but have not been diagnosed with it," said Dr. Eaton.

###
"Coeliac disease and schizophrenia: population based case control study with linkage of Danish national registers" was written by William W. Eaton, Preben Bo Mortensen, Esben Agerbo, Majella Byrne, Ole Mors and Henrik Ewald. Mortensen, Agerbo and Byrne are with the National Centre for Register-Based Research, Aarhus University, Denmark. Mors and Ewald are with the Institute of Basic Psychiatric Research, Aarhus, Denmark.

The research was funded by the Danish National Research Foundation, Stanley Medical Research Institute and the National Institute for Mental Health.