The Association between Allergic Rhinitis and Schizophrenia in the North of Iran: a large scale, population based cross-sectional study

The literature indicates a link between schizophrenia and a disturbance in innate and adaptive immunity. However, the results about allergic rhinitis have been inconsistent so far. The aim of this population-based study was to investigate the prevalence and clinical features of allergic rhinitis in patients with schizophrenia.

This cross-sectional study was performed on 998 patients and 1000 age- and sex-matched control subjects from March 2013 to August 2014. All participants were assessed by the Score for Allergic Rhinitis (SFAR) questionnaire and nasal smear (for eosinophilia) investigation. Symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS). Univariable and multivariable logistic regression models were fitted to estimate adjusted odds ratios.

The mean age of subjects was 45.0 years, and 61.0% of subjects of either group were male. About 26.5% of subjects in the case group and 21.0% in the control group had allergic rhinitis. The patients with schizophrenia were found to be at an increased risk for allergic rhinitis (adjusted OR 1.41, 95% CI 1.08-1.83) compared to control subjects. Furthermore, multivariable logistic regression identified the affect subscale on the BPRS as a risk factor of allergic rhinitis (P=0.004).

Our results suggest that the prevalence of allergic rhinitis is higher in patients with schizophrenia. However, the impact of type and severity of allergic rhinitis on the course of schizophrenia must be investigated in further trials.