GBA1 and Lewy body dementia: CSF α-synuclein is not yet proven as a biomarker, while Aβ, tau, and phospho-tau measurements may be more useful in determining concomitant AD pathology or predicting cognitive decline.e20 Glucocerebrosidase (GBA) mutations are overrepresented in DLBe21 but most individuals with DLB do not have them.