A study published in the March American Journal of Psychiatry found a stronger association between schizophrenia and autoimmune diseases than previously suspected.

Dr. William W. Eaton, of the Johns Hopkins University, Baltimore, and colleagues analyzed information about 7,704 schizophrenia patients and their parents from three databases (the Danish Psychiatric Register, the National Patient Register, and a register with socioeconomic information) and compared the data with a sample of matched comparison subjects and their parents. They found that a family history of any autoimmune disease was associated with a 45% increased risk of developing schizophrenia. Five autoimmune disorders appeared more frequently in patients with schizophrenia prior to schizophrenia onset as well as in the patients’ parents: thyrotoxicosis, intestinal malabsorption, acquired hemolytic anemia, interstitital cystitis, and Sjögren’s syndrome. More research on family histories of autoimmune disease in schizophrenia patients may provide clues to causal factors common to both types of disorders.