For NfL, higher levels were associated with increased risk across all diseases even after full adjustment, with the strongest associations observed in ALS (HR 1.69; 95% CI, 1.58–1.80, p < 0.001), followed by APD (HR 1.51; 95% CI, 1.22–1.87, p < 0.001), AD (HR 1.31; 95% CI, 1.22–1.41, p < 0.001), and PD (HR 1.14; 95% CI, 1.05–1.23, p < 0.001). Here, NEFL is linked to Alzheimer disease.