A Nationwide Study on the Risk of Autoimmune Diseases in Individuals With a Personal or a Family History of Schizophrenia and Related Psychosis
ABSTRACT OBJECTIVE Previous research has found an increased risk of schizophrenia in individuals with autoimmune diseases and smaller but significant associations with a family history of autoimmune diseases. This study investigates, for the first time, the association between schizophrenia and subsequent autoimmune diseases (the reverse temporality) and also considers the effect of infections, a possible risk factor for both schizophrenia and autoimmune diseases. METHOD Danish nationwide registers were linked to establish a cohort of 3.83 million people, identifying 39,364 individuals with schizophrenia-like psychosis and 142,328 individuals with autoimmune disease. Data were analyzed using survival analysis and adjusted for calendar year, age, and sex. RESULTS Individuals with schizophrenia had an elevated risk of subsequent autoimmune diseases, with an incidence rate ratio of 1.53 (95% CI=1.46-1.62). Among persons without hospital contacts for infections, the effect of having schizophrenia was smaller, with an increased incidence rate ratio of 1.32 (95% CI=1.22-1.43) for autoimmune diseases. For individuals with schizophrenia as well as hospital contacts for infections, the combined risk of autoimmune diseases was 2.70 (95% CI=2.51-2.89). A family history of schizophrenia slightly increased the overall risk of developing autoimmune diseases (incidence rate ratio=1.06, 95% CI=1.02-1.09). Autoimmune diseases developed subsequently in 3.6% of people with schizophrenia, and 3.1% of people with autoimmune diseases had a family history of schizophrenia. CONCLUSIONS The increased risk of subsequent autoimmune diseases in individuals with schizophrenia may involve neuropsychiatric manifestations from the undiagnosed autoimmune disease, medical treatment or lifestyle associated with schizophrenia, or common etiological mechanisms, such as infections and shared genetic factors.
- Neurology Psychiatry and Brain Research 12/2013; 19(4):170–173. DOI:10.1016/j.npbr.2013.10.003 · 0.10 Impact Factor
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ABSTRACT: Numerous studies have reported a reduced risk of rheumatoid arthritis (RA) in schizophrenia. The mechanisms are unknown, but recent genome-wide association studies of schizophrenia have shown strong associations with markers spanning the major histocompatibility complex region, indicating a possible role for adaptive immunity also in schizophrenia. In this population-based cohort study, we assess the associations between RA and schizophrenia and the extent to which any observed associations are specific to RA/schizophrenia. We then extend the assessments per RA subtype and to risks in first-degree relatives. The study population included every individual identified in the Swedish Population Register born in Sweden between 1932 and 1989. The risk for RA in schizophrenia was significantly decreased (hazard ratio [HR] = 0.69, 95% CI = 0.59-0.80), but similar reductions were noted for osteoarthritis (a noninflammatory joint disorder) and ankylosing spondylitis (a non-RA inflammatory disorder). Comparable associations were seen in schizoaffective subjects while no significant associations were observed in bipolar disorder. Overall, first-degree relatives of schizophrenia patients were not at reduced risk of RA, but the risk for seronegative RA was significantly decreased in children and siblings of schizophrenia probands (HR = 0.13, 95% CI = 0.02-0.95 and HR = 0.67, 95% CI = 049-0.92, respectively). In conclusion, our intraindividual analyses suggest that differential misclassification bias is an important factor for the observed inverse association and emphasize the need of optimized care-provision for nonpsychiatric symptoms in schizophrenia patients. Our familial analyses indicted the possibility of an inverse coinheritance of schizophrenia and seronegative RA.Schizophrenia Bulletin 04/2014; 40(6). DOI:10.1093/schbul/sbu054 · 8.61 Impact Factor
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ABSTRACT: BACKGROUND: N-methyl-d-aspartate receptor (NMDAR) antibodies have been documented in the serum of individuals with primary psychiatric disorders from several independent cohorts, but these findings have not been systematically assessed in aggregate or in relation to methodological covariates. METHODS: We searched MEDLINE, EMBASE, and PsycINFO for studies in any language that provided data on NMDAR antibody seropositivity or absolute serum titers in schizophrenia or schizoaffective, bipolar, or major depressive disorders. We used a random effects model to pool estimates across studies. RESULTS: Nine studies met the eligibility criteria. Five studies (3387 participants) provided data on NMDAR antibody seropositivity in psychiatric versus control groups based on high-specificity seropositivity thresholds (cell-based assays [CBAs]: 1:320 dilution, 1:200 dilution, visual score>1; enzyme-linked immunosorbent assay [ELISA]: 90(th) percentile of control titers). Meta-analysis showed significantly higher odds of NMDAR antibody seropositivity among those with schizophrenia or schizoaffective, bipolar, or major depressive disorders compared with healthy controls (odds ratio [OR], 3.10; 95% confidence interval [CI], 1.04-9.27; P=.043; I(2)=68%). Four studies (3194 participants) provided outcome data for these groups based on low-specificity seropositivity thresholds (CBAs 1:10 dilution; ELISA: 75(th) percentile of control titers). Meta-analysis showed greater heterogeneity and no significant between-group difference (OR, 2.31; 95% CI, 0.55-9.73; P=.25; I(2)=90%). Seropositive participants in psychiatric groups had various combinations of IgG, IgM, and IgA class antibodies against NR1, NR1/NR2B, and NR2A/NR2B subunits. Subgroup analysis revealed significantly higher odds of seropositivity among all participants based on 1:10 versus 1:320 dilution seropositivity thresholds (OR, 4.56; 95% CI, 2.41-8.62; P<.001; I(2)=0%; studies=2, n=2920), but no apparent difference between first-episode and chronic schizophrenia or schizoaffective disorder (OR, 1.15; 95% CI, 0.19-7.24; P=.88, I(2)=43%, studies=2, n=1108). Average NR2A/NR2B antibody titers determined by ELISA were significantly higher among participants with first-episode schizophrenia (P<.0001) and acute mania (P<.01) compared with healthy controls. Levels decreased by 58% at 8weeks in first-episode schizophrenia, and by about 13% at 4days in acute mania. CONCLUSIONS: Individuals with schizophrenia or schizoaffective, bipolar, or major depressive disorders are collectively about three times more likely to have elevated NMDAR antibody titers compared with healthy controls based on high-specificity, but not low-specificity, seropositivity thresholds, though considerable methodological and statistical heterogeneity exists. Evidence concerning the effect of disease state and time of serum acquisition is varied and consistent, respectively. Adequately powered longitudinal studies employing standardized assay methods and seropositivity threshold definitions, and quantifying NMDAR antibodies in both sera and cerebrospinal fluid are needed to further elucidate the clinical and pathophysiological implications of this association. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved. KEYWORDS: Antibodies; Bipolar disorder; Immunoglobulin; Major depressive disorder; Meta-analysis; N-methyl-d-aspartate receptor; Psychoimmunology; Schizoaffective disorder; Schizophrenia; Systematic reviewSchizophrenia Research 05/2014; 157(1-3). DOI:10.1016/j.schres.2014.05.001 · 4.43 Impact Factor