SNCA and Alzheimer disease: Previous studies have shown that APOE ε4 is linked to DLB in both AD and non-AD cases.23,24 However, some studies have also shown that APOE ε4 is only associated with DLB when there is a significant amount of co-existing Alzheimer’s pathology.25-27 This finding contradicts the idea that APOE ε4 independently drives α-synuclein pathology.