Effect of organismal rhythmic activity on Aβ clearance by the glymphatic system

Abnormal deposition of β-amyloid (Aβ) is a significant pathological feature of neurodegenerative diseases, particularly Alzheimer's disease (AD). The glymphatic system (GS) plays a crucial role in Aβ clearance. Various rhythmic activities of the organism dynamically influence Aβ clearance by modulating GS function. In this paper, we systematically review the mechanisms linking cardiovascular rhythms, respiratory rhythms, neural rhythms, circadian rhythms, and exercise patterns to Aβ clearance via the GS. Cardiovascular rhythms affect cerebral perfusion pressure and vascular pulsation to regulate GS transport efficiency; respiratory rhythms modulate intracranial pressure and cerebrospinal fluid (CSF) circulation through thoracic pressure variations; neural rhythms (including delta waves during non-rapid eye movement (NREM) sleep and neurovascular coupling) synchronize neuro-glial-vascular interactions to enhance GS clearance. Circadian rhythms coordinate these primary rhythms by regulating melatonin levels and cerebral blood flow, while exercise patterns adjust GS function via aquaporin-4 (AQP4) polarization. Additionally, we elaborate on the cascade effect of AD resulting from rhythmic dysregulation. A thorough understanding of how rhythmic activities impact Aβ clearance by the GS may offer new perspectives and potential intervention strategies for the prevention and treatment of AD through the concept of "synchronized multiple rhythms"-a novel framework that integrates multi-rhythm synergy. Clinically, this work provides a theoretical basis for developing targeted interventions, such as personalized exercise timing regimens, respiratory rhythm training, and closed-loop neurovascular feedback devices, to restore GS function in AD patients.