In the DLB group, GFAP, NfL, P-tau181, and P-tau231, but not Aβ42/40 ratio, were associated with global cognitive impairment (MMSE) at baseline (Aβ42/40: β = −13.18, 95% CI −56.42 to 30.05, p = 0.549; GFAP: β = −9.25, 95% CI −12.06 to −6.44, p < 0.001; NfL: β = −7.41, 95% CI −10.28 to −4.54, p < 0.001; P-tau: β = −2.61, 95% CI −3.99 to −1.24, p < 0.001; P-tau: β = −2.42, 95% CI −3.67 to −1.17, p < 0.001) when corrected for age and sex. This evidence concerns the gene NEFL and Lewy body dementia.