AUTHOR=Zhang Xiangyu , Zhang Runlong , Zhang Yuanfeng , Lu Tao 

TITLE=Associations between attention-deficit/hyperactivity disorder and allergic diseases: a two-sample Mendelian randomization study

JOURNAL=Frontiers in Psychiatry

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2023.1185088

DOI=10.3389/fpsyt.2023.1185088

ISSN=1664-0640

ABSTRACT=Background:
In some observational studies, attention-deficit/hyperactivity disorder(ADHD) has been linked to allergic diseases, but the findings are debatable. This study aimed to determine whether attention-deficit/hyperactivity disorder are causally related to allergic asthma, allergic rhinitis, pollen allergy, allergic urticaria and allergic conjunctivitis using the two-sample Mendelian Randomization (MR) approach.
Methods:
We did a two-sample Mendelian randomization (MR) study, which chose single nucleotide polymorphisms (SNPs) that are highly associated with attention-deficit/hyperactivity disorder (ADHD) levels from the Psychiatric Genomics Consortium (PGC) on 20,183 cases and 35,191 controls as our instruments. Outcomes datasets included genome-wide association study (GWAS) summary statistics of allergic asthma (10877 cases and 180942 controls), allergic rhinitis (8430 cases and 298829 controls), pollen allergy (4555cases and 301734 controls), and allergic urticaria (1792 cases and 299491 controls) allergic conjunctivitis (15567 cases and 293587 controls) from the FinnGen datasets. Inverse variance weighted, MR-Egger, weighted median, were used to estimate the causal association between ADHD and allergic diseases. Cochran's Q test were used to quantify the heterogeneity of instrumental variables. MR-Egger intercept test, leave-one-out analysis, and the funnel plot were all used in sensitivity analyses.
Results:
Mendelian randomization (MR) analyses indicated that ADHD in inverse variance weighted [odds ratio (OR) = 1.0612; 95% confidence interval (CI), 1.0192-1.1049; p = 0.0039] increased the risk of allergic asthma lightly. In MR sensitivity analyses of the weighted median, a similar association was found. But no evidence for an effect of ADHD on allergic asthma risk was found in additional methods: MR-Egger (OR：0.9592, 95% CI: 0.8384-1.0974, p = 0.5457), and weighted median (OR: 1.0341, 95% CI: 0.9785-1.0929, p = 0.2330). Also, no strong evidence for an effect of ADHD on other allergic diseases (allergic rhinitis, pollen allergy, allergic urticaria and allergic conjunctivitis) incidence was found using the inverse-variance weighted (IVW) method, weighted median method and MR-Egger regression.
Conclusions: 
Although several studies have found a link between ADHD and allergic diseases, our findings suggest that this elevated risk is minor.