Considering that APOE4 is associated with DLB risk, and that DLB APOE4 carriers also exhibit greater cognitive impairment than non-carriers, we also review studies that investigate the effect of APOE4 toward the brains of DLB subjects (Ballard et al., 2001; Boot et al., 2013; Tsuang et al., 2013; Guerreiro et al., 2018; Mirza et al., 2019; Rongve et al., 2019; Kaivola et al., 2021; Nasri et al., 2022). Here, APOE is linked to Cognitive impairment.