Schizophrenia in patients with atopic disorders with particular emphasis on asthma: a Danish population-based study.
Autoimmune diseases and infections have been associated with an increased risk of schizophrenia that could be rooted in inflammatory mechanisms.
However, other diseases characterized by a heightened immune response, such as atopic disorders, remain to be thoroughly investigated. The aim of this study was to investigate whether atopic disorders in the individual or in a first-degree relative affect the risk of developing schizophrenia.
We linked two nationwide population-based registers: the Danish Psychiatric Central Register and the National Hospital Register. Two longitudinal designs were used: a cohort study and a case/sibling study. Rate ratios (RRs) and accompanying 95% confidence intervals (CIs) were obtained.
Hospital contact with any atopic disorder increased the RR of schizophrenia by 1.45 (95% CI=1.31-1.90). The increased risk was mainly driven by asthma: 1.59 (95% CI=1.31-1.90); this was confirmed when cases were compared with siblings instead of the background population.
Hospital contact with other included atopic disorders (atopic dermatitis, urticaria and allergic rhinitis) increased the risk of schizophrenia significantly only if they were combined into one group. Hospital contact with asthma in a first-degree relative did not significantly increase the risk of schizophrenia.
This study indicates the existence of an association between atopic disorders in general and asthma in particular and the risk of developing schizophrenia. The study adds to a growing body of literature suggesting the possible involvement of immune processes in the pathophysiology of schizophrenia.
Further Readings of Interest
Prevalence and risk of atopic disorders among schizophrenia patients: a nationwide population based study.
Findings indicated high comorbidity, with 20.2% of schizophrenia patients (approximately one in five) experiencing concurrent atopic disorders. Moreover, schizophrenia in patients was independently associated with a 1.3-fold increased risk (95%CI=1.24-1.39) of concurrent asthma, after adjusting for socio-demographic characteristics.
Yet the risk of diagnosed allergic rhinitis and urticaria was 23% (95%CI=0.74-0.81) and 26% (95%CI=0.72-0.77) lower, respectively, among schizophrenia patients compared to people without any psychiatric disease.
Comorbidity of allergic and autoimmune diseases in patients with autism spectrum disorder: A nationwide population-based study
Patients with ASDs had increased risks of asthma (OR = 1.74, 95%CI = 1.51–1.99),
allergic rhinitis (OR = 1.70, 95%CI = 1.51–1.91),
atopic dermatitis (OR = 1.52, 95%CI = 1.30–1.78),
urticaria (OR = 1.38, 95%CI = 1.12–1.69) and
type 1 diabetes (OR = 4.00, 95%CI = 1.00–16.00),
and a trend toward increasing comorbidity with Crohn’s disease (OR = 1.46, 95%CI = 0.90–2.35).
Our results support the association between ASDs and allergic diseases, and autoimmune comorbidities (type 1 diabetes and Crohn’s disease). Further basic study is required to elucidate the possible underlying mechanisms and roles of allergy immunity and autoimmunity in the etiology of ASDs.