Similar to the chronic PD model, the expression levels of aforementioned genes also decreased in PBMCs of PD patients and this reduction may represent an adaptive mechanism of patient's body to the neurodegenerative condition.1 Consistent with our result, as reported by Delbarba et al, AD PBMCs show a significant decrease in PGC1α expression, while PCG1α was unchanged in mild cognitive impairment (MCI) patients. The gene discussed is PPARGC1A; the disease is Alzheimer disease.