Identification of Mediating Pathways Between Attention Deficit/Hyperactivity Disorder and Coronary Artery Disease and Heart Failure: A Two-Step Multivariable Mendelian Randomization Study

Attention deficit/hyperactivity disorder (ADHD) is associated with an increased risk of cardiovascular diseases (CVDs). However, whether this is a causal relation and how ADHD may predispose to a higher risk of CVD needs to be determined. We aimed to assess the causal association between ADHD and both coronary artery disease (CAD) and heart failure (HF), and to quantify the mediating effects of potential modifiable mediators. We conducted a two-step, two-sample Mendelian randomization (MR) study using SNPs as genetic instruments for exposure and potential mediators. Leveraging summary data on the latest genomewide association studies for ADHD, proposed mediators (i.e., metabolic factors, inflammatory factors, lifestyle behaviors, psychiatric disorders, and educational attainment), CAD and HF, we decomposed the total effect of ADHD on each outcome into direct and indirect effects through multiple mediators. Genetically predicted ADHD was associated with increased odds of CAD (<i>OR</i> 1.13; 95% CI [1.07, 1.19]), with educational attainment (EA) being the largest contributor (32.27% mediation, 95% CI [18.33%, 56.93%]). Body mass index (BMI), type 2 diabetes (T2D), EA, smoking initiation (SI), and depression jointly explained 83.59% (95% CI [63.95%, 101.49%]) of the association. Genetically predicted ADHD was associated with increased odds of HF (<i>OR</i> 1.11; 95% CI [1.05, 1.19]), with SI being the largest contributor (35.87% mediation, 95% CI [13.75%, 100.14%]). BMI, T2D, and SI jointly explained 82.39% (95% CI [45.90%, 131.60%]) of the association. The findings support a causal relationship between ADHD and both CAD and HF. Several modifiable risk factors substantially mediate these associations, suggesting potential targets for interventions aimed at reducing CVD risk in individuals with ADHD.