Ok, let’s start this post with a massive disclaimer: much of the content of this post is purely hypothetical. It’s my speculation and interpretation of studies, and there is no conclusive evidence that I am aware of directly linking yoga with Alzheimer’s disease – definitely not as a cure or even as a preventative measure.
The idea came after reading news this morning of a study that found a link between Alzheimer’s and circadian rhythms – that’s the ‘clock’ that regulates our biological functions, including when we wake up and go to sleep, when we are hungry, when we go to the toilet etc etc, all against the 24-hour day cycle. Disturbed sleep can wreck havoc with our circadian rhythm, as I’m sure those of us who have experience jet lag will know. So that’s where sleep and sleep hygiene comes in.
What did the study actually find?
Alzheimer’s is caused by the accumulation of plaques on the brain, made up of a protein called amyloid-beta. This protein normally gets cleared up by immune cells called macrophages, which basically eat it and destroy it. In Alzheimer’s, this clean-up mechanism malfunctions, and the protein keeps building up until the plaques form.
The study found that the normal clean-up of amyloid-beta by macrophases happens on a circadian rhythm; when the circadian rhythm of the macrophages was disrupted, they were unable to clean-up amyloid-beta. Because sleep disturbances can interfere with the circadian clock, it’s possible that better sleep could help to maintain healthy circardian rhythms and either delay Alzheimer’s onset or help to make it less severe. Here’s a link to the study itself.
Massive caveat: the study was done using mouse cells, and not even in real-live mice but using mouse cells in a dish (what we call an in vitro study). This is standard practice, but it means it’s quite early stages in terms of finding significance and applicability. But interesting nonetheless.
Why do I keep bringing up yoga?
This is a blog that primarily focuses on yoga/mind–body practices and science/health, so it’s kind of part of the job description.
But joking aside, sleep is one of those topics that comes up a lot in the context of the benefits of yoga. I’ve written before about the potential for yoga nidra to help support healthy sleep, improving sleep quality and reducing insomnia in various different populations (including older adults, where Alzheimer’s is a bit more relevant).
There are also studies and systematic reviews on yoga and other mind–body practices more broadly that find improvements in subjective sleep quality and reduction in insomnia (eg here, here and here). Although it’s important to point out that benefits on sleep have been noted for other physical activities (eg this systematic review assessed both mind–body practices and activities like walking and cycling) and that some studies have found no benefits (eg see this systematic review). My general theory is that yoga helps us relax, which means we fall asleep more easily and potentially get better quality sleep too. If this is a topic of interest, then this book on yoga and sleep is worth exploring.
Finally, I came across this review article, that claims to detail the potential benefits of yoga on Alzheimer’s disease and other conditions that involve mild cognitive impairment, but unfortunately I don’t have access to it. If you do, perhaps you can send it to me 😉 I did cover evidence of benefits of yoga on cognitive function in my post on ageing, but whether any of these studies are relevant to Alzheimer’s plaque formation or circadian rhythms, I have no idea.
Regardless, it seems like doing things that help to support sleep (and maintain healthy circadian rhythms) is a good idea for life in general.
Yoga may be one way to do that. Especially yoga nidra. At the very least, you’ll hopefully feel really relaxed.