Notably, for years, amyloid, tau, and alpha-synuclein hypotheses have dominated AD and PD research (Zhang et al., 1989; Stefanis, 2012; Ozansoy and Başak, 2013), but recently, researchers have suggested that mitochondrial or bioenergetic dysfunction may be related to etiology of AD or PD (Winklhofer and Haass, 2010; Wellstead and Cloutier, 2011; Desler et al., 2017; Onyango et al., 2017; Swerdlow et al., 2017). This evidence concerns the gene SNCA and Alzheimer disease.