How important is sleep in the process of developing Alzheimer disease? A new study in PLOS Biology reveals that brain activity during deep sleep can help clear away toxic proteins in the brain (PLOS Biology, June 1, 2021). Inadequate sleep with too little time spent in deep sleep (not dreaming) could lead to a buildup of Alzheimer’s disease proteins such as beta amyloid.
Research Linking Sleep to Alzheimer’s Disease Proteins:
Researchers at The Pennsylvania State University recruited 118 volunteers. There were 62 participants with mild cognitive impairment, 18 with significant memory concerns and 7 with Alzheimer’s disease. Brain imaging demonstrated that people with better flow of cerebrospinal fluid out of the brain during non-dreaming sleep had lower levels of beta amyloid. Those with Alzheimer disease and those with memory problems had less movement of the cerebrospinal fluid during sleep. This study suggests that the body has a natural means of lowering Alzheimer’s disease proteins and reduce beta amyloid accumulation in the brain. It also highlights the importance of good sleep quality for maintaining brain health.
Previous Study Showed a Connection Between Poor Sleep and Dementia Risk:
Older people who don’t sleep well appear to be at higher risk for dementia. Several years ago, researchers questioned healthy older people in Baltimore about their sleep patterns (JAMA Neurology, online, Oct. 21, 2013). At that point, none of the volunteers had any signs of cognitive impairment. Participants underwent PET scanning of their brains within five years. Such positron emission tomography can detect levels of beta amyloid proteins, a marker for Alzheimer’s disease.
People who reported less sleep had more of these toxic Alzheimer’s disease proteins in their brains. The worse their sleep quality, the greater the amount of beta amyloid found on PET scans. This study was limited to people reporting themselves on how well they slept. As a result, the study could not distinguish between REM sleep and the deep sleep that appears essential for cerebrospinal flow.
Sleep Research Clarifies Glymphatic System:
The results of this study are consistent with animal research demonstrating that sleep deprivation results in greater concentrations of beta amyloid. In just the past several years, scientists have uncovered that cerebrospinal fluid moves through something called the glymphatic system (Neurochemical Research, Dec. 2015). Although the initial studies on this system for removing waste from brain tissue was done in animals, doctors now recognize its importance for humans (JAMA, May 17, 2021). Apparently, glymphatic flow during sleep helps sweep out Alzheimer’s disease proteins.
Unfortunately, we don’t yet have trials to show whether better sleep can prevent or slow the progression of Alzheimer’s disease. Achieving deep sleep can be challenging, as many sleeping pills may increase the risk for dementia.
Learn More:
To learn more about overcoming insomnia, we suggest our Guide to Getting a Good Night’s Sleep. There is also information about avoiding Alzheimer’s disease and dementia in our interview with Dr. Murali Doraiswamy. You might also want to listen to Show 1246: Getting the Sleep You Need Even in Anxious Times.
