PPARGC1A and early-onset autosomal dominant Alzheimer disease: Studies show that alterations in mitochondrial biogenesis co-activators such as peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) contribute to the rise of metabolic diseases including diabetes, obesity, cardiomyopathy, Alzheimer’s disease, and Parkinson’s disease [26,27,28].