MAPT and Alzheimer disease: Hyperphosphorylation of tau negatively affects complex I activity with a decrease of ATP production, an increase of oxidative stress, dissipation of mtΔΨ, induction of the mitochondrial fission, and excessive mitochondrial fragmentation in postmortem brains from AD patients and in murine models (Manczak et al., 2011; Eckert et al., 2014).