Figure 1:The circadian rhythm, an internal clock in all organisms, has been found to have correlations with the development of Alzheimer’s Disease.
Source Credit: The Conversation (LINK)
Researchers have recently discovered the close relationship between the circadian rhythm and the development of Alzheimer’s Disease (AD)—a brain disorder that gradually destroys cognitive abilities such as memory. The circadian rhythm is a natural cycle that repeats every 24 hours in all organisms. This internal process regulates when the body tries to sleep and wake up. Although much research has already revealed the importance of sleep, scientists recently discovered a new reason why humans should try to follow the circadian rhythm regularly.
According to The Conversation, the circadian rhythm controls the brain’s ability to remove proteins related to AD in the brain. One of the major causes of AD is an accumulation of a protein called amyloid-beta. These proteins clump together to form “plaques,” which disrupt cell functions and trigger cognitive issues. As a result, it is important for the body to have a system that prevents such protein accumulation that exacerbates the progress of AD.
Furthermore, the new study discovered that the cells that are responsible for the clean-up of amyloid-beta follow the circadian rhythm. In an experiment, the researchers used macrophages—white blood cells that innate the immune system—from mice. When the scientists exposed the macrophages to amyloid-beta, they found that the cells eliminated the protein at certain periods of time during a 24-hour period. In addition, when the cells lost the circadian rhythm, the amyloid-beta did not get cleared as normal. This finding signifies the importance of following the circadian rhythm for the brain.
“The disruption of the proper timing of amyloid-beta clearance could be one of the reasons we see an increase in plaques that form in the brain during Alzheimer’s disease,” said Dr. Jennifer Hurley, a researcher at Rensselaer Polytechnic Institute. “As we age, and more so in Alzheimer’s patients, this rhythm disappears. This loss could lead to the increase of amyloid-beta in the brain.”
As mentioned by Dr. Hurley, part of the reason why the elderly develop AD may be attributed to the loss of the circadian rhythm as humans age. This research may be a major breakthrough that allows scientists to focus their attention on how to prevent the loss of this rhythm and how to artificially remove the accumulation of plaques in the brain. If this method is discovered, we may be a step closer to finding a cure for AD.
Q&A:
Sally: Are there any relationships between the circadian rhythm and other proteins that cause AD?
The direct link between circadian rhythm and AD is tied to the protein amyloid-beta. However, in the end, following the circadian rhythm and having good sleep is healthy for your overall body. Being able to sleep well at the right time not only allows amyloid beta to clear the brain but also reduces stress and better control over your feelings—some conditions that scientists say contribute to the development of AD.
John: How would you suggest people regulate their circadian rhythm, particularly in relation to previous studies relating the circadian rhythm to human sleep patterns and exposure to light?
The first thing that people should do is follow a routine. In order to regulate their circadian rhythm, it is important that people go to bed at the same time every day. Once a routine is established, other things people can do are exercise, avoid naps, stay away from alcohol and caffeine, and reduce time spent looking at screens. Furthermore, it is important to have the least exposure to light 2 hours before usual bedtime, throughout the night, and 1 hour after usual wake-up time.
Wooseok: Considering how the loss of the circadian rhythm plays a significant role in the development of AD, would the younger population with nighttime shift work be exposed to a greater risk of getting AD?
While it seems likely that night-shift workers would develop AD more frequently, current research shows that the relation between night shift work and the risk of dementia is statistically insignificant. However, there are also studies suggesting that permanent night workers have a higher chance of developing AD. So although this question needs further research, it seems like workers who work at night for a long period of time have a greater chance of developing dementia.
Works Cited
Busch, Morten. “Permanent Night Workers Develop Dementia More Frequently.” Science News, sciencenews.dk/en/permanent-night-workers-develop-dementia-more-frequently.
“Circadian Control of Immune Cell Linked to Clearance of Alzheimer's Protein.” Proteomics & Metabolomics from Technology Networks, www.technologynetworks.com/proteomics/news/circadian-control-of-immune-cell-linked-to-clearance-of-alzheimers-protein-358437.
“Effects of Light on Circadian Rhythms.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 1 Apr. 2020, www.cdc.gov/niosh/emres/longhourstraining/light.html#:~:text=The circadian clock is most,is ready to fall asleep.
Eleftheria Kodosaki Research Associate in Neuroimmunology. “Alzheimer's Disease Linked to Circadian Rhythm – New Research in Mice.” The Conversation, 15 Feb. 2022, theconversation.com/alzheimers-disease-linked-to-circadian-rhythm-new-research-in-mice-177090.
Nabe-Nielsen, Kirsten, et al. “Night Shift Work, Long Working Hours and Dementia: a Longitudinal Study of the Danish Work Environment Cohort Study.” BMJ Open, BMJ Publishing Group, 24 May 2019, www.ncbi.nlm.nih.gov/pmc/articles/PMC6538206/#:~:text=Overall, the positive association between,a higher incidence of dementia.
“Study Finds Link between Alzheimer's and Circadian Clock.” The Guardian, Guardian News and Media, 10 Feb. 2022, www.theguardian.com/society/2022/feb/10/study-finds-link-between-alzheimers-and-circadian-clock.
schneik4. “Do You Need to Reset Your Circadian Rhythm?” Cleveland Clinic, Cleveland Clinic, 17 Dec. 2021, health.clevelandclinic.org/how-to-reset-circadian-rhythm/.
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