DLB participants stratified for amyloid status differed significantly in plasma Aβ42/40 ratio (decreased in amyloid abnormal: β = −0.008, 95% CI −0.016 to −0.0003, p = 0.01) and P-tau (increased in amyloid abnormal, P-tau181: β = 0.246, 95% CI 0.011–0.481; P-tau231: β = 0.227, 95% CI 0.035–0.419, both p < 0.05), but not in GFAP (β = 0.068, 95% CI −0.018 to 0.153, p = 0.119), and NfL (β = 0.004, 95% CI −0.087 to 0.096, p = 0.923) concentrations. The gene discussed is GFAP; the disease is Lewy body dementia.