SIRT1 activity was reduced in PD (25%; p < 0.01), PDD (23%; p < 0.05), DLB (30%; p < 0.001) and AD (22%; p < 0.05) compared to controls (F: 6.265, p < 0.001) whereas no significant difference was seen among the disease groups (Fig. 8). This evidence concerns the gene SIRT1 and Alzheimer disease.