Asthma, corticosteroid use and schizophrenia: A nationwide population-based study in Taiwan.

Wei-Chen Wang,Roger S Mcintyre,Mong-Liang Lu,Mei-Hing Ng,Kuo-You Huang,Charles Tzu-Chi Lee,Ming-Hong Hsieh,Meng-Jer Hsieh,Yena Lee,Vincent Chin-Hung Chen,Ping-Hsun Wu

doi:10.1371/journal.pone.0173063

Abstract

ObjectiveAsthma and corticosteroid use have been implicated as possible risk factors for schizophrenia. The retrospective cohort study herein aimed to investigate the association between asthma, corticosteroid use, and schizophrenia.MethodLongitudinal data (2000 to 2007) from adults with asthma (n = 50,046) and without asthma (n = 50,046) were compared on measures of schizophrenia incidence using Taiwan’s National Health Insurance Research Database (NHIRD). Incidence of schizophrenia diagnosis (ICD-9 codes 295.XX) between 2000 and 2007 were compared between groups. Competing risk-adjusted Cox regression analyses were conducted, adjusting for sex, age, residence, socioeconomic status, corticosteroid use, outpatient and emergency room visit frequency, Charlson comorbidity index, and total length of hospital stays days for any disorder.ResultsOf the 75,069 subjects, 238 received a diagnosis of schizophrenia. The mean (SD) follow-up interval for all subjects was 5.8 (2.3) years. After adjusting for potential confounding factors, asthma was associated with significantly greater hazard ratio for incident schizophrenia 1.40 (95% CI = 1.05, 1.87). Additional factors associated with greater incidence of schizophrenia were rural residence, lower economic status, and poor general health. Older age (i.e. ≥65 years) was negatively associated with schizophrenia incidence. Corticosteroid use was not associated with increased risk for schizophrenia.ConclusionsAsthma was associated with increased risk for schizophrenia. The results herein suggest that a convergent disturbance in the immune-inflammatory system may contribute to the pathoetiology of asthma and schizophrenia.

Highlights

Schizophrenia is a severe and chronic mental disorder that affects approximately one percent of the general population globally [1]
After adjusting for potential confounding factors, asthma was associated with significantly greater hazard ratio for incident schizophrenia
Corticosteroid use and schizophrenia funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication

Summary

Introduction

Schizophrenia is a severe and chronic mental disorder that affects approximately one percent of the general population globally [1]. One hypothesis posits that inflammatory disturbances may contribute to the etiology of schizophrenia. Several epidemiological studies have reported on an increased risk for schizophrenia among those with autoimmune disorders and/or severe infections [7, 8]. The association between schizophrenia and autoimmune/infectious disorder suggests that there may be a convergent neurobiological substrate [9]. Peripheral inflammation has been associated with greater permeability of the blood—brain barrier, facilitating the entry of immune molecules into the brain [10]. A disturbance in innate and adaptive immunity might contribute to the pathogenesis of schizophrenia [11]

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Results

Conclusion