In summary, all these analyses demonstrated a robust and significant causal relationship between 7 circulating inflammatory factors and ADHD, including Eotaxin levels, GDNF, FGF-23, TNF-related activation-induced cytokine levels, Adenosine Deaminase levels, CD40L receptor levels, and Urokinase-type plasminogen activator levels. Here, GDNF is linked to attention deficit-hyperactivity disorder.