The epidemiologic evidence linking autoimmune diseases and psychosis.

This review summarizes the epidemiologic evidence linking autoimmune diseases and psychosis. The associations between autoimmune diseases and psychosis have been studied for more than a half century, but research has intensified within the last decades, since psychosis has been associated with genetic markers of the immune system and with excess autoreactivity and other immune alterations. A range of psychiatric disorders, including psychosis, have been observed to occur more frequently in some autoimmune diseases, such as systemic lupus erythematosus and multiple sclerosis. Many autoimmune diseases involve multiple organs and general dysfunction of the immune system, which could affect the brain and induce psychiatric symptoms. Most studies have been cross-sectional, observing an increased prevalence of a broad number of autoimmune diseases in people with psychotic disorders. Furthermore, there is some evidence of associations of psychosis with a family history of autoimmune disorders and vice versa. Additionally, several autoimmune diseases, individually and in aggregate, have been identified as raising the risk for psychotic disorders in longitudinal studies. The associations have been suspected to be caused by inflammation or brain-reactive antibodies associated with the autoimmune diseases. However, the associations could also be caused by shared genetic factors or common etiologic components such as infections. Infections can induce the development of autoimmune diseases and autoantibodies, possibly affecting the brain. Autoimmune diseases and brain-reactive antibodies should be considered by clinicians in the treatment of individuals with psychotic symptoms, and even if the association is not causal, treatment would probably still improve quality of life and survival.