NEW YORK (Reuters Health) Mar 24 - Results of a study published in the March issue of the American Journal of Psychiatry suggest an association between schizophrenia and a large range of autoimmune diseases.

"Individuals with schizophrenia and their relatives tend to have either higher or lower than expected prevalences of autoimmune disorders, especially rheumatoid arthritis, celiac disease, autoimmune thyroid diseases, and type 1 diabetes," Dr. William W. Eaton, of the Johns Hopkins University, Baltimore, Maryland, and colleagues write.

In a large epidemiological study, the researchers examined the association between schizophrenia and a range of autoimmune diseases. They used data from the Danish Psychiatric Register, the National Patient Register, and a register containing socioeconomic information. Included were 7704 patients diagnosed with schizophrenia between 1981 and 1998 and their parents, as well as matched control subjects and their parents.

Subjects with one or more autoimmune diseases had a 45% increased risk of schizophrenia, and schizophrenia patients had a higher prevalence of nine autoimmune disorders compared with the controls. The parents of schizophrenic patients had a higher prevalence of 12 autoimmune diseases compared with the parents of the controls.

Thyrotoxicosis, celiac disease, acquired hemolytic anemia, interstitial cystitis, and Sjogren's syndrome occurred more often in schizophrenic patients and their parents compared with the controls and their parents, the researchers report.

"In future clinical studies it may be interesting to search for a family history of autoimmune diseases, and specific autoantibodies, in patients with schizophrenia," Dr. Eaton's team suggests. "Eventually, individual or family disease comorbidity may help to elucidate shared etiologic pathways."