Autoimmune diseases, bipolar disorder, and non-affective psychosis.
OBJECTIVE
Clinic-based studies of immune function, as well as comorbidity of autoimmune diseases, bipolar disorder, and schizophrenia, suggest a possible autoimmune etiology. Studies of non-affective psychosis and schizophrenia suggest common etiologies. The objective was to determine the degree to which 30 different autoimmune diseases are antecedent risk factors for bipolar disorder, schizophrenia, and non-affective psychosis.


METHODS
A cohort of 3.57 million births in Denmark was linked to the Psychiatric Case Register and the National Hospital Register. There were 20,317 cases of schizophrenia, 39,076 cases of non-affective psychosis, and 9,920 cases of bipolar disorder.


RESULTS
As in prior studies, there was a range of autoimmune diseases which predicted raised risk of schizophrenia in individuals who had a history of autoimmune diseases, and also raised risk in persons whose first-degree relatives had an onset of autoimmune disease prior to onset of schizophrenia in the case. These relationships also existed for the broader category of non-affective psychosis. Only pernicious anemia in the family was associated with raised risk for bipolar disorder (relative risk: 1.7), suggesting a small role for genetic linkage. A history of Guillain-Barré syndrome, Crohn's disease, and autoimmune hepatitis in the individual was associated with raised risk of bipolar disorder.


CONCLUSIONS
The familial relationship of schizophrenia to a range of autoimmune diseases extends to non-affective psychosis, but not to bipolar disorder. The data suggest that autoimmune processes precede onset of schizophrenia, but also non-affective psychosis and bipolar disorder.
Eaton
William W
WW
Department of Mental Health, Johns Hopkins University, Baltimore, MD 21205, USA. weaton@jhsph.edu
Pedersen
Marianne G
MG
Nielsen
Philip R
PR
Mortensen
Preben Bo
PB
D000293:Adolescent; D000328:Adult; D001327:Autoimmune Diseases / Q000150:complications* / Q000235:genetics; D001714:Bipolar Disorder / Q000150:complications* / Q000235:genetics; D015331:Cohort Studies; D003718:Denmark; D005260:Female; D006801:Humans; D008297:Male; D011618:Psychotic Disorders / Q000150:complications* / Q000235:genetics; D012042:Registries; D055815:Young Adult