Secondary analysis showed a dose-dependent risk of developing PDD associated with APOE-ε4: when compared to non-carriers, carriers of one ε4 allele were at 3.1 times higher risk of progressing to dementia, while those who carried two ε4 alleles were at 6.4 times higher risk (Table 3, Fig. 2F). This evidence concerns the gene APOE and dementia.