Current research on Alzheimer’s Disease (AD) suggests that it is the abnormal build-up of proteins like amyloids, which deposit plaques in and around brain cells, that lead to degeneration of cognitive function. Until recently, there was no evidence for any specialized systems within the brain that removed waste outside of the ventricular system.  However, the discovery and research of the glymphatic system, a specialized macroscopic waste clearance system, in the past decade may offer greater insight into how the brain prevents AD – and why it sometimes fails (1). 

The glymphatic system is formed by astroglial cells making up many perivascular tubes which run throughout the brain (1). It serves an analogous role to the lymphatic system throughout the rest of the body, and the two are connected at the dura and the other large vessels of the skull (2). The waste collected by the glymphatic system drains downstream into the lymphatic system at these connections. The first studies looking into the glymphatic system found that soluble amyloid beta proteins and tau oligomers, the build up of which are both associated with AD, are carried out of the brain from the interstitial fluid by the glymphatic system. A following study also showed that the glymphatic system’s activity is enhanced during slow-wave sleep. Together, these findings suggest that early interventions in sleep structure and duration could prove to be preventative therapeutics for cognitive decline in AD patients (2). For more on the links between sleep and AD, see this article by Esurgi. 

References

1. Jessen, N. A., Munk, A. S. F., Lundgaard, I., & Nedergaard, M. (2015). The Glymphatic 

System: A Beginner’s Guide. Neurochemical Research, 40(12), 2583–2599. 

https://doi.org/10.1007/s11064-015-1581-6

2. Benveniste, H., Liu, X., Koundal, S., Sanggaard, S., Lee, H., & Wardlaw, J. (2019). The 

Glymphatic System and Waste Clearance with Brain Aging: A Review. Gerontology65(2), 106–119.

https://doi.org/10.1159/000490349

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