MAPT and hippocampal atrophy: Decreases in CSF Aβ1-42 are associated with a cascade of events consisting of fibrillar Aβ deposition (positive amyloid-PET), increased tau in the CSF (CSF tau), hippocampal atrophy and hypometabolism and finally cognitive and clinical deficits in the later stages (Bateman et al., 2012).