Objective Sleep Architecture Alterations and Sleep-Dependent Brain Clearance Dysfunction Across the Early Alzheimer's Disease Continuum: A Systematic Review.
Level 3 - non-randomized controlled study
Systematic review of predominantly cross-sectional observational studies
PubMed 42652858 · doi:10.3390/jcm15166454
What was done
A systematic review searched four databases (PubMed, Embase, Cochrane Library, and PsycINFO) plus supplementary searches to identify human studies evaluating objective sleep metrics (polysomnography or electroencephalography) and brain clearance or glymphatic biomarkers across the Alzheimer's disease continuum. Clearance metrics included diffusion tensor imaging along the perivascular space (DTI-ALPS), perivascular space burden, blood oxygen level-dependent-cerebrospinal fluid coupling, or direct tracer-based clearance imaging. Out of 344 screened records and 64 full-text reviews, four studies met the inclusion criteria.
What was found
The abstract reports no numerical values, pooled estimates, or effect sizes. Across the four included studies, preserved slow-wave sleep, slow-wave activity, and sleep oscillatory coupling were associated with more favorable glymphatic biomarkers, whereas disrupted sleep architecture, reduced sleep efficiency, and altered oscillatory coupling were associated with impaired brain clearance or glymphatic dysfunction.
Why it matters
This review highlights emerging human evidence linking electrophysiologically measured deep sleep disruption to impaired glymphatic clearance across the Alzheimer's continuum.
Limits
The total evidence base is limited to four studies that are predominantly cross-sectional, precluding causal inference. Furthermore, clearance was measured primarily using indirect surrogate neuroimaging metrics rather than direct clearance validation, and sample sizes of individual studies were not reported in the abstract.
Cited by
- supports The glymphatic system clears metabolic waste and interstitial fluid from the brain primarily during deep sleep.