Assessment of the bidirectional causal association between allergic diseases and neuropsychiatric disorders

This study aimed to explore the causal associations between allergic diseases and neuropsychiatric disorders via bidirectional Mendelian randomization (MR) analysis.

This study employed three methodologies for MR analysis, primarily utilizing the inverse variance weighted approach, while supplementing with MR-Egger regression and the weighted median method. Sensitivity analyses encompassed Cochran's Q test, MR-PRESSO test, MR-Egger regression intercept and leave-one-out analysis, all serving to validate the reliability of the reported findings.

The forward MR analysis results indicated that bipolar disorder (BD) was positively correlated with allergic asthma (AA) (OR = 1.204) and allergic rhinitis (AR) (OR = 4.647), and depression was positively correlated with AA (OR = 1.141) and atopic dermatitis (AD) (OR = 1.103). The reverse MR analysis outcomes unveiled a negative association between allergic urticaria (AU) and autism spectrum disorder (ASD) (OR = 0.780), a positive correlation between allergic conjunctivitis (AC) and tic disorder (TD) (OR = 1.020). Sensitivity analysis indicated an absence of significant heterogeneity or potential horizontal pleiotropy.

AA and AD acted as risk factors for depression; AA and AR increased the risk of BD; ASD served as a protective factor for AU; TD was a risk factor for AC.