Disrupted drainage in the aging brain: Meningeal lymphatic decline as a convergent axis of vulnerability

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The aging brain depends on coordinated fluid transport, immune surveillance, and clearance of metabolic byproducts to preserve cognitive and physiological homeostasis. While peripheral lymphatic decline is well established, growing evidence implicates brain-draining lymphatic pathways, particularly meningeal lymphatic vessels and their downstream drainage to deep cervical lymph nodes, as an aging-sensitive axis that intersects with neuroinflammation and neurodegenerative vulnerability. Here, we systematically analyzed peer-reviewed studies published between 2003 and 2025 that examined age-related changes in intracranial and cervical lymphatic circuits across human imaging, histopathology, and experimental models. Ninety-six studies met the inclusion criteria. Four themes emerged. First, aging is associated with coordinated lymphatic remodeling across peripheral and central compartments, including reduced vessel integrity, stromal remodeling, and involution of draining lymph nodes. Second, meningeal lymphatic vessels exhibit age-related, region-specific structural and molecular alterations that may coincide with impaired cerebrospinal and interstitial fluid handling and altered immune regulation. Third, advanced magnetic resonance imaging, including contrast-enhanced and non-contrast approaches, reveals reproducible age-associated changes in dural and cervical lymphatic-related signals across the lifespan, while remaining an indirect proxy for flow and transport. Fourth, early therapeutic efforts suggest that brain-draining lymphatic function may be modifiable. These approaches include augmenting meningeal lymphangiogenic signaling with VEGF-C or its cofactor; and, in selected translational settings. Collectively, the evidence supports meningeal and cervical lymphatic decline as a plausible, potentially modifiable contributor to aging-related brain vulnerability across disorders such as Alzheimer’s disease and Parkinson’s disease, while underscoring the need for more direct functional measurements and longitudinal human studies. Conceptual schematic of age-associated changes in meningeal lymphatic architecture and cervical drainage pathways. (A) In younger individuals, studies support lymphatic-associated handling of cerebrospinal and interstitial fluids (CSF/ISF) across dorsal (convexity-associated) and skull base–associated dural compartments, with drainage pathways that can connect to structurally intact deep cervical lymph nodes (dCLNs). Additional pathways including the spinal meningeal drainage and nasopharyngeal drainage pathways are represented. Solid green arrows indicate proposed directions of efflux reported across experimental and human studies, without implying relative magnitude or dominance of individual pathways. Bulk CSF absorption through arachnoid granulation-to-dural venous sinus pathways is shown with solid blue arrows, reflecting the predominant route of CSF clearance in adult humans. (B) With aging, emerging evidence across models and human datasets suggests structural remodeling of meningeal lymphatic vessels and age-associated alterations in cervical lymph nodes that may constrain drainage capacity. Dashed arrows indicate potential attenuation or dysregulation of efflux rather than measured flow rates. Concurrently, dCLNs may exhibit fibrotic remodeling and reduced receptivity to afferent lymphatic input, consistent with a disruption of central–peripheral drainage continuity. These changes may contribute to altered CSF/ISF handling, neuroimmune dysregulation, and accumulation of metabolic byproducts in the aging brain. Bulk CSF absorption through arachnoid granulations remains preserved and is represented with solid blue arrows. Insets illustrate representative ultrastructural features reported in dorsal and skull base–associated meningeal lymphatics and dCLNs, including vessel wall thickening, altered perivascular organization, nodal involution, and change in meningeal lymphatic flow relative to maintained arachnoid granulation function as represented in proximity to the superior sagittal sinus. This schematic integrates multiple lines of emerging evidence, including non-contrast MRI and human histological analyses, and is intended as a conceptual framework rather than a quantitative depiction of compartment-specific flow or hierarchy. The figure summarizes a proposed trajectory of structural and functional vulnerability that may contribute to increased susceptibility to neurodegenerative disease, perioperative complications, and delayed recovery in older adults. • Aging remodels meningeal lymphatics and weakens CSF drainage. • Deep cervical lymph nodes undergo fibrotic involution that limits outflow. • Regional lymphatic decline perturbs neuroimmune homeostasis with age. • Lymphatic impairment may increase vulnerability to neurodegenerative disease.

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