SNCA and dementia: Alpha-synuclein (α-syn) is considered the primary constituent protein of Lewy bodies, which is the defining hallmark of Lewy body dementia (LBD) including Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB) (Hijaz and Volpicelli-Daley, 2020; Koga et al., 2021).