# Glymphatic System Dysfunction in Central Nervous System Diseases

## TL;DR

The glymphatic system clears brain waste, and its dysfunction is linked to many neurological diseases, offering new therapeutic targets.

## Contribution

This review identifies glymphatic dysfunction as a unifying pathophysiological mechanism across diverse central nervous system diseases.

## Key findings

- Glymphatic dysfunction is associated with impaired clearance of neurotoxic proteins in acute and chronic neurological disorders.
- Key mechanisms include AQP4 mislocalization, perivascular space obstruction, and vascular stiffening.
- Translational strategies like sleep optimization and anti-inflammatory approaches may restore glymphatic function.

## Abstract

The glymphatic system is a perivascular cerebrospinal fluid (CSF)–interstitial fluid (ISF) exchange pathway that supports brain homeostasis by clearing metabolic waste and neurotoxic proteins. Across central nervous system diseases, converging evidence indicates that glymphatic dysfunction represents a shared pathophysiological axis linking vascular, astroglial, inflammatory, and sleep‐related disturbances to impaired solute clearance.

In this review, we synthesize mechanistic and clinical evidence for glymphatic impairment in acute brain injury (ischemic and hemorrhagic stroke, traumatic brain injury) and chronic neurological disorders (Alzheimer's disease, Parkinson's disease, cerebral small vessel disease, multiple sclerosis, idiopathic normal pressure hydrocephalus, idiopathic intracranial hypertension, epilepsy, and headache disorders). Major mechanisms include (i) aquaporin‐4 (AQP4) depolarization/mislocalization at astrocytic endfeet, reducing perivascular water transport; (ii) perivascular space compression or obstruction from cytotoxic/vasogenic edema, blood‐derived products, protein aggregates, or altered extracellular matrix; (iii) loss of arterial pulsatility and vascular stiffening, weakening the driving forces for convective exchange; (iv) blood–brain barrier disruption and neuroinflammation, which remodel perivascular architecture and amplify clearance failure; and (v) sleep and autonomic dysregulation, including altered noradrenergic tone, which suppresses glymphatic activity during periods when clearance is normally maximal. Clinically, glymphatic dysfunction can be probed using diffusion tensor imaging–analysis along the perivascular space (DTI‐ALPS), contrast‐enhanced MRI approaches, and structural surrogates such as enlarged perivascular spaces, with emerging associations to cognition, mood, and disease severity. Finally, we discuss translational strategies aimed at restoring clearance, including sleep/circadian optimization, vascular risk control, anti‐inflammatory approaches, AQP4‐ and TRPV4‐oriented targets, and neuromodulation. Mechanism‐guided, standardized imaging and longitudinal interventional studies are needed to establish glymphatic biomarkers as actionable therapeutic and prognostic tools.

Glymphatic Dysfunction in Neurological Disorders: The glymphatic system is a brain‐wide clearance system that removes neurotoxic waste via AQP4‐mediated CSF‐ISF exchange. Dysfunction through AQP4 mislocalization, BBB injury, and inflammation annihilates clearance and causes acute (stroke, TBI) and chronic disease. Lifestyle, sleep, and vascular interventions hold promise for restoring glymphatic function and improving neurological outcomes.