MAPT and Alzheimer disease: Of key importance to select the right cognitive tools is the documented evidence that clinically healthy Mexico City children and young adults exhibit the neuropathological and cerebrospinal fluid (CSF) features associated with AD, i.e., tau hyperphosphorylation with pre-tangles, amyloid beta42 (Aβ42) diffuse plaques, and low CSF Aβ42 (Calderón-Garcidueñas et al., 2008a, 2011, 2012a, 2013a, 2015a).