The Glymphatic System: a brain-wide clearance system
Until recently, the brain was not thought to have an active system for removing metabolic waste products (like the lymphatic system in the rest of the body). That changed when animal, and then human, research identified a brain-wide clearance system that uses perivascular space to allow cerebral spinal fluid (CSF) to penetrate neuronal tissue and exit carrying metabolites. The system is thought to be driven by arterial pulsation, which results in convective flow in these perivascular spaces. There is some evidence that the system is moderated by the awake-sleep state, with initial studies suggesting increased functioning during sleep, when interstitial spaces are larger and CSF production is highest.
The implications for cognitive health are significant, given that many dementias are caused by the neurodegenerative accumulation of misfolded proteins (e.g., beta-amyloid in Alzheimer’s and alpha-synuclein in Parkinson’s). Global-wide efforts are being directed at identifying methods to manipulate this system, in hopes it may offer a method to slow or even prevent neurodegenerative disease.
Our multi-departmental collaborative work has developed novel multi-modal neuroimaging techniques to measure purported human glymphatic functioning, in vivo. By combining these techniques with neurological and neuropsychological evaluations, our work is advancing the understanding of how glymphatic neurophysiology relates to behavior and cognition. Recently, our research demonstrated that cerebrovascular disease likely moderates glymphatic system functioning, suggesting metabolic and cardiovascular health may impact the effectiveness of this brain-waste clearance system. We are also investigating potential methods of influencing the glymphatic system, such as delineating the effects of general anesthesia versus natural sleep, as well as the impact vigorous exercise has on glymphatics.
Learn More:
Discovery of the glymphatic system
Review of the glymphatic system
Current controversies and areas requiring clarification
Please call 615-875-9750 for more information on any of these studies.