In particular, previous results obtained in the authors’ laboratory, on autopsy specimens from the cortex of AD brains, classified by the Braak staging system of neurofibrillary pathology, have demonstrated that the expression levels of SIRT1 are markedly reduced with the progression of AD, i.e. with the accumulation of hyperphosphorylated tau [7]. The gene discussed is SIRT1; the disease is Alzheimer disease.