In the group of patients with dementia of different types (53 with Alzheimer’s disease, 17 with vascular dementia and 32 with mixed dementia) a significant association was reported of the global DNA methylation and markers of the folate status with variations of genes previously reported as involved in dementia (among them PON1 192 Q/R polymorphism) [133]. The gene discussed is PON1; the disease is dementia.