Plasma neurofilament light chain (NfL), a biomarker of neuronal axonal injury, independently predicted major cardiovascular events in 46,129 UK adults over nearly 10 years of follow-up. Each one-unit increase in NfL raised the risk of cardiovascular death by 79%, heart failure hospitalization by 50%, stroke by 38%, and heart attack by 35%, even after adjusting for traditional risk factors like age, smoking, and diabetes. This finding bridges neurology and cardiology in an unexpected way, suggesting that subclinical neuronal damage may serve as an early warning system for cardiovascular disease. The brain-heart connection has emerged as a critical frontier in preventive medicine, with growing evidence that vascular health affects both organs simultaneously through shared pathways like inflammation and endothelial dysfunction. While NfL modestly improved risk prediction beyond standard clinical scores, its greatest value may lie in identifying high-risk individuals who appear healthy by conventional measures. However, this preprint awaits peer review, and the practical implications remain unclear—particularly whether NfL testing would be cost-effective for population screening. The observational design also cannot establish whether neuronal injury directly causes cardiovascular events or simply reflects common underlying pathology.