MAPT and Alzheimer disease: Studies have demonstrated that the normal cellular energy metabolism is necessary for normal functioning of the brain (28), and when availability of ATP is low in the brain, faulty amyloid precursors protein (APP) metabolism and hyperphosphorylation of the tau-protein are high, that induce production of neuritic placques and neurofibrillary tangles, respectively, which are prominent histopathological markers of AD (28).