Notably, intraoperative blood transfusion escalated delirium risk by 147.3% (OR = 2.473), attributed to oxidative stress from free hemoglobin in stored blood and transfusion-related immunomodulation (e.g., CD40L-mediated neuroinflammation) that upregulates MMP-9 expression at the blood–brain barrier, exacerbating central inflammation (35). The gene discussed is MMP9; the disease is delirium.