Remarkably, impairment of one-carbon metabolism in animal models can reproduce AD-like pathological features: accumulation of P-tau (Sontag et al., 2007; Zhang et al., 2008; Wei et al., 2011); enhanced amyloidogenesis (Pacheco-Quinto et al., 2006; Zhang et al., 2009; Zhuo et al., 2010; Zhuo and Pratico, 2010); increased phosphorylation of APP at the regulatory Thr-668 site (Sontag et al., 2007; Zhang et al., 2009); increased sensitivity to amyloid toxicity (Kruman et al., 2002); and cognitive impairment (Bernardo et al., 2007; Wei et al., 2011; Rhodehouse et al., 2013). Here, MAPT is linked to Alzheimer disease.