Numerous studies over the past decade have established a strong link between poor sleep and Alzheimer’s disease (AD). Poor sleepers have elevated levels of toxins in the brain, a hallmark of AD. However, the mechanism linking sleep to elevated toxin levels has remained unknown.
Noam Alperin, PhD, professor of radiology and biomedical engineering at the University of Miami Miller School of Medicine, and Ritambhar Burman, a biomedical engineering graduate student, believe they have found that link. The team’s paper describing a mechanism that enhances removal of toxins from the brain during sleep, titled “CSF-to-blood toxins clearance is modulated by breathing through craniospinal CSF oscillation,” is published in the Journal of Sleep Research.
With every heartbeat, a small amount of cerebrospinal fluid (CSF) moves back and forth between the cranium and the spinal canal. “For years, the physiologic functions of these oscillations have been overlooked,” Dr. Alperin said. “The CSF is getting a lot done by going nowhere.”
Over the past four years, Dr. Alperin and Burman have used an advanced MRI technique that captures flow in real time to measure the amount of CSF that oscillates between the cranium and the spinal canal during different breathing modes. “The larger this amount is, the better the exchange between toxin-rich cranial CSF and toxin-poor spinal CSF,” Alperin noted.
The researchers learned that certain breathing patterns that occur primarily during slow-wave sleep increase CSF movement, thereby enhancing the transfer of soluble brain toxins to the spinal canal, where they are absorbed into the blood. While most investigators have focused on toxin clearance from the brain to the CSF, Alperin and Burman focused on the CSF-to-blood clearance.
“These exciting findings could lead to development of a device that helps elderly poor sleepers clear daily metabolic waste products from their brains and slow down the progression to dementia,” Dr. Alperin explained. “We are delighted to share our novel methodology for improved clearance of toxins during sleep with another research group who will perform real-time MRI studies and EEG recording overnight to demonstrate the method’s feasibility in poor sleepers.”