MAPT and Brain atrophy: Evidence of neurodegeneration markers (e.g., increased total CSF Tau; brain atrophy; glucose hypometabolism), in the absence of Aβ deposition demonstrated by Aβ cerebral PET and/or by low CSF Aβ1-42 levels, may instead characterize a wide range of clinical conditions called Suspected Non-Alzheimer Pathology (SNAP) [22].