MAPT and Alzheimer disease: In cognitively normal older adults (mean age ~ 73–75), low frequency EEG signal during NREM sleep (1–2 Hz; indicative of delta waves prominent in SWS) exhibit an inverse relationship with AD pathology most prominently with AV-1451 tau positron emission tomography (PET) signal [60, 74], and in AD patients (mild-moderate) sleep–wake disturbances have been shown to correlate with CSF levels of phosphorylated tau [75].