In addition, reduced SIRT1 levels have been found either in the Parkinsonian mimetic-induced PD models [63,69,88] or the frontal cortex of PD patients [76], and several genetic variants in the SIRT1 promoter region have been found in sporadic PD patients [94], further suggesting SIRT1 as a therapeutic target for PD [43]. This evidence concerns the gene SIRT1 and Parkinson disease.