A meta-analysis of the relationship between sleep and β-Amyloid biomarkers in Alzheimer's disease

Sleep has an important role for long-term memory consolidation. As deficits in learning and memory are clinical characteristics of Alzheimer's disease (AD), it has been suggested that disruptions in sleep-mediated consolidation processes are related to AD. Indeed, sleep disruptions and sleep disorders are often comorbid with AD and perhaps precede the onset of AD symptoms as a risk factor. Additionally, research has shown that sleep disruptions and disorders are associated with accumulation of β-amyloid (AB), a neuropathologic hallmark and biomarker of AD. However, the studies that have investigated the relationship between sleep disturbances and AB burden have been heterogenous in design and quality, leaving it unclear whether the overall effect is statistically significant. As such, this paper investigated the relationship between sleep disturbances and AB burden by meta-analytically integrating reported correlations that have been published to date. Results revealed that higher levels of cerebral AB (lower AB42/40 ratios) were related to shorter sleep durations, highlighting the importance of total sleep time in supporting the clearance of AB during slow-wave sleep. Herein we also controlled for heterogeneity in the included studies by conducting several moderator analyses, showing an important role for age, sex, cognitive impairment, sleep disorders, and education in influencing the associations between sleep disturbances and AB.