SNCA and Alzheimer disease: Protein aggregates containing α-synuclein (α-syn), which eventually forms larger Lewy bodies (LBs), are seen in Parkinson’s disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy, and in some forms of Alzheimer’s disease (AD), all neurodegenerative diseases associated with aging (Arima et al., 1999; Francis, 2009; Lippa et al., 1998).