Preliminary findings from the Harvard Brain Aging Study suggest amyloid and tau signals on PET imaging are related to individual sleep architecture. Among 14 women who participated in this study (mean age 74.1 ± 1.97), there was a positive correlation between the percent time spent in N1 sleep and inferior temporal tau levels (P = .006) and cortical amyloid burden (P = .01). In contrast, the percent of time spent in slow wave sleep (N3) and REM sleep each independently correlated inversely with inferior temporal levels of tau (P = .016, P = .05, respectively). These correlations were independent of total sleep time and participant age. No association between sleep disordered breathing and amyloid or tau levels was observed.
In this study, participants had home-level polysomnography in individuals who were cognitively intact at recruitment. Participants are followed longitudinally and screened annually with multimodal imaging including Pittsburgh Compound B PET scans to detect amyloid deposition and Tau imaging using the F18-labeled ligand (T807). All participants also have annual cognitive assessments that include the Preclinical Alzheimer’s Cognitive Composite (PACC), to define predictive factors of preclinical Alzheimer’s disease.
These findings suggest that sleep architecture and sleep disturbances could be a surrogate marker for cognitive impairment and a tool for predicting dementia risk and measuring effect of treatments.