Alzheimer's disrupts circadian rhythms of plaque-clearing brain cells

172 pointsposted 11 hours ago
by gmays
(medicine.washu.edu)

29 Comments

pedalpete

7 hours ago

Here’s a link to the paper [1].

I work in the neurotech/sleeptech space, and Alzheimer’s is one of the endpoints we’re working toward.

On a first read, it seems the authors frame everything through a circadian lens. Their view is that circadian genes regulate glial function, and that when those rhythms are disrupted, clearance breaks down, inflammation increases, and amyloid accumulates, contributing to Alzheimer’s.

There’s another perspective in sleep science that looks at restorative function. The physiological work of sleep like slow-wave activity and glymphatic flow which may be the driver. From that view, amyloid build-up impairs glymphatic clearance, creating a downward spiral of poorer clearance and more accumulation.

Circadian timing is certainly an important modulator, but it’s not the whole story. Without EEG or even basic sleep-wake data, it’s hard to know whether the changes in circadian” gene expression reported here reflect intrinsic clock disruption or simply reduced slow-wave restorative function in these mice.

I've linked to two research papers[2],[3] in AD which are working with the same principles of our work at https://affectablesleep.com

[1] https://doi.org/10.1038/s41593-025-02067-1 [2] https://doi.org/10.1016/j.jagp.2024.07.002 [3] https://doi.org/10.1093/ageing/afad228

mobilejdral

10 hours ago

The title is a bit link-bait. It should really be "Disrupting circadian rhythms of plaque-clearing brain cells is associated with Alzheimer's"

> He found that too much of YKL-40, which is linked to Alzheimer’s risk in humans, leads to amyloid build-up, an accumulation that is a hallmark of the neurodegenerative disease.

There are countless studies that highlight how genetics or lifestyle and other factors that result in a reduction of estrogen signaling are associated with Alzheimer's. Estrogen, primarily activated at night decreases the expression of the YKL-40 gene. All of the known interventions, from vitamin D, Mg, to gut, choline, etc all can improve estrogen signaling, decreasing YKL-40 gene. One can end up with Alzheimer's from many different routes so interventions depend on the person.

If there was a pill on the market today that would only increase the plaque-clearing all this really does is move the needle, they still have reduced estrogen signaling and the next weakest part of the system would fail such as from animpaired immune system and they will probably die of pneumonia.

But we could back up and say what is the most common cause of the global reduced estrogen signaling? Often increased oxy-androgens (which increase as we age), so for example 11-ketotestosterone (11-KT) which can't convert to its estrogen form results in upregulates HSD17B2. Why do we have so much inflammation causing increased oxy-androgens from the adrenals? Senescence cells releasing inflammatory factors SASP. More time more time spent on repair resulting in identity loss and mesenchymal drift. All a fancy way of saying we get older and will probably die from whatever weakest part of the system we have genetically. Fix one thing and something else breaks instead.

And for those that want to bring in the most well known genetic mutation APOE e4: APOE e4/e4 has elevated choline demands hindering estrogen signaling as well as raising HDL and lowering LDL. Low estrogen influences Cholesteryl Ester Transfer Protein, raising HDL and lowers LDL beyond what e4/e4 does by itself. With less choline and less phosphatidylcholine, it decreases GLUT1 transporters reducing glucose entering the brain. All of the above leads to an escalating amyloid plaque burden. Then reduced deep sleep and the glymphatic system cleaning is reduced too and you have Alzheimer's.

The above was just from memory probably had an error, but the point is Alzheimer's is not "simple" like this article pretends.

amenhotep

5 hours ago

Your general point about how complicated it is is well taken, but a theoretical pill that stages off Alzheimer's at the expense of immunocompromise and means you die of pneumonia with your faculties mostly intact seems like a huge win. I don't think we're bothered about Alzheimer's as a proxy for old age, I think it's because dementia is a uniquely horrible disease.

mobilejdral

4 hours ago

I am not saying that if there was a pill on the market today that would increase plaque-clearing there wouldn't still be dementia, simply that they would probably then die from pneumonia.

One needs to also dive into neurogenesis. Elevated HPA Axis activation which brought us the oxy-androgens also gives use higher cortisol and lower α-MSH which promote neurogenesis. This elevated cortisol is one of the classic hallmarks of Alzheimer's. Estrogen signaling is also an important part of neurodevelopment. So someone with Alzheimer's usually has low α-MSH and low estrogen signaling and overall reduced neurodevelopment. Need to fix these to prevent dementia.

The various stuff that has been found to reduces dementia also improve estrogen signaling. Estrogens are an incredibly old hormone used in regulating a ton of basic cell function. Keep ERa functioning well and you get not only better amyloid plaque clearance, but healthier DNA repair, immune system, etc and better neurogenesis. A lot of stuff that improves longevity ultimately just keeps this going.

There is a Alzheimer's Choline camp which is where we know that Choline supplements is associated with improved Alzheimer's. With low estrogen signaling you have lower N-methyltransferase so less Choline in the body as it is how the body makes it. Less Choline, less SAM via BHMT, less SAM, less clearance of 2-OHE1, less ERa activation, and ... less choline in a loop. Supplement with Choline and it helps not only with the APOE e4 which consumes more Choline, but undoes this is what this theory is about.

As we are having fun with this, decrease the BHMT from less Choline and it shifts from BHMT-mediated methionine synthesis to MTR-mediated pathways, consuming 5-MTHF resulting in slower THF regeneration. Slower THF regeneration impairs the folate cycle, increasing reliance on serine as a one-carbon donor. Elevated serine flux upregulates PHGDH, which promotes IKKα-HMGB1 signaling which drives amyloid pathology and neuron death! Which brings us to probably my favorite paper from this year. "Transcriptional regulation by PHGDH drives amyloid pathology in Alzheimer’s disease" https://www.cell.com/cell/fulltext/S0092-8674(25)00397-6

I myself don't put myself in the Choline camp, but more see Alzheimer's simply as one failure mode on the metabolic estrogen axis of which is induce in certain genetic or diet configurations. In this mode it results in a number of cascading failures until death. Some genetics/diet are fairly easy to halt/undo the spiral of death which is seen in how there are some things that are known to improve Alzheimer's in some, but not all patients. I can induce Alzheimer's via the gut, diet, inflammation, adrenals, sleep, a whole host of ways, anything that starts the cascade.

An example of an unlucky genetic case is when someone has 3 CYP21A2 rather than 2, they end up with hypercortisolism and nearly always they will get Alzheimer's if there is no intervention. This is a rare genetic case, but simply a way to break the axis elsewhere with the same effect.

Obscurity4340

9 hours ago

What is the word on the best current and ubiquitous prophylactics, like you said Vit D(3?)

mobilejdral

9 hours ago

For this particular situation on D3 I personally (who is not your doctor) would go with vitamin D3-loaded nanoemulsion. The reason is that Vit D influences how tryptophan is converted down the 5-HTP and serotonin path or the Kynurenine path. We want higher serotonin AND specifically in the brain. The higher serotonin means better melatonin which not only increase sleep, but increase the ERα expression which we are trying to increase... in the brain.

There is a recent study on this showing how this form can provide better results in the brain. https://www.sciencedirect.com/science/article/pii/S305047402...

In general: Omega-3, bcomplex with choline etc all have studies. Really it depends on the individual and what their genetic weakest issue is. Its old and boring, but eat healthy, don't eat before bed, exercise (dance!), and get good sleep always apply.

Obscurity4340

9 hours ago

Are you aware of any association with stimulant treatment re alzheimers? Probably the sleep?

wyldfire

4 hours ago

> with vitamin D3-loaded nanoemulsion

This is a substance that is used as a dietary supplement? Or how is it delivered?

DarkmSparks

6 hours ago

last I heard everything amyloid/plaque burden was suspect after

https://www.nytimes.com/2023/07/19/us/stanford-president-res...

It looks very much like they are a symptom rather than a cause. They have got very good at medicines that remove amyloid/plaques, they only physical outcome was massive brain bleeds and death, plus a little

https://www.ncbi.nlm.nih.gov/search/research-news/13804/

before being withdrawn for all the reasons they resigned

https://www.pharmaceutical-technology.com/analyst-comment/bi...

absolute disaster :(

pedalpete

5 hours ago

Tau and it's relationship to Amyloid, are the current top hypothesis.

Another way to look at why the removal of amyloid may not be effective in repairing damage is to think of it like a blocked pipe.

A pipe gets blocked, and the pipe itself gets damaged, causing a leak. The block can be removed, but that doesn't repair the pipe.

In my example, the pharmaceuticals are removing the blockage, but the damage is still done.

Having said that, I believe that as we learn more about what we currently call Alzheimer's, we'll discover that we've been lumping multiple diseases under a single label. I believe the amyloid hypothesis, and Type 3 diabetes hypothesis, both have merit. There may well be others.

DarkmSparks

4 hours ago

Traumatic brain injury (TBI) can lead to the rapid formation of amyloid plaques....

So entirely possible they are simply part of how or brain deals with brain cell death.

Its possible at this point it's not a "disease" at all, at least no more than the STI we are all dieing from (our parents had sex and now we get to die).

Prior to 1900 or so, average life expectancy was something like 25 or 30, our brains simply never evolved to live as long as they do now, some people age faster than others..

The problem for the scientific basis is all the brain research has gone into plaques and ignored all the other conditions that lead to cell death and aging, it's going to be a while before other directions can be properly explored, and plaques for sure still have the momentum despite failing at every turn.

anon84873628

4 hours ago

Plaques have not failed at every turn. This seems to be a myth repeated every time an article like this pops up. Yes there were specific instances of fraud, but this did not invalidate the whole research avenue. Researchers are in fact doing exactly what you suggest, and understanding plaques is a lever into those underlying dysfunctions... Like say circadian rhythm perhaps.

And I don't know why you would talk about average life expectancy when median expectancy or expectancy at adolescence are much more relevant metrics (that probably don't agree with your point).

DarkmSparks

4 hours ago

Name a single success.

The best treatments on the market slows cognative decline measurements for up to 6 months "maybe" (could just be the result of pain relief), dates back to like 2001, and have nothing to do with amyloids.

>but this did not invalidate the whole research avenue

Indeed, multiple treatments in very expensive human trials based on the research avenue failing to show any kind of measurable clinical efficacy invalidates the research area.

The latest being from just a few days ago

https://www.biospace.com/drug-development/alector-scraps-dem...

pedalpete

3 hours ago

You're confusing repairing the damage with the cause.

Just because amyloid/tau cause the damage, that doesn't mean removing them repairs.

If rust weakens a structural piece of steel, removing the rust does not repair the integrity of the steel.

DarkmSparks

3 hours ago

There is exactly zero evidence to show they cause the damage, the only evidence that once existed to say they caused the damage used 100% faked results, which didnt emerge until after the treatments based on it causing the damage failed to show any clinical benefit and stanford launched an investigation into the prof whose students produced the evidence.

They created several treatments that stopped them forming (most prominent being biogens). The result was no difference in cognitive function vs placebo and some 20% of the people who took it suffering from a heamoralgic stroke (which they covered up).

freddie_mercury

6 hours ago

Not really true. See for instance this link

"Opponents call the amyloid hypothesis zombie science, propped up only by pharmaceutical companies hoping to sell off a few more anti-amyloid me-too drugs before it collapses. Meanwhile, mainstream scientists . . . continue to believe it without really offering any public defense. Scott was so surprised by the size of the gap between official and unofficial opinion that he asked if someone from the orthodox camp would speak out in its favor."

https://www.astralcodexten.com/p/in-defense-of-the-amyloid-h...

DarkmSparks

6 hours ago

From that link

"and only slow progression a relatively small amount."

They don't even do that. they _do_ remove plaques, they _do not_ have any statistically significant effect on MMSE degradation.

plus I only see the comments that point out the entire scientific basis for them was based on faked research.

The way I had it "simply" described was "the plaques are basically dead brain cells, the problem is the brain cells rapidly dieing, not cleaning up the corpses afterwards".

either way, the faked research set dementia research back at least 2 decades and wasted billions of dollars on failed medications with no benefits and horrific side effects (that they tried to cover up).

yard2010

8 hours ago

I'm far from an expert but maybe the air we breathe is toxic? It makes stuff oxidize and go bad. It just takes enough of this poison and that's it.

JumpCrisscross

8 hours ago

> maybe the air we breathe is toxic?

I suppose since atmospheric oxygen is mostly of biological origin, yes, you're technically correct in labelling oxygen in the air as a toxin.

tyre

8 hours ago

There was a study[0] connected to videos[1] of particular flashing that trigger plaque-clearing rhythms in the brain.

Maybe placebo but my mind feels quietly clearer after watching. It could be that simply slowing down and clearing my mind for that time would do the same.

[0]: https://journals.plos.org/plosbiology/article?id=10.1371/jou...

[1]: https://vimeo.com/1023275135/378186db55

Previous HN discussion: https://news.ycombinator.com/item?id=41942096

monkeydreams

8 hours ago

> It could be that simply slowing down and clearing my mind for that time would do the same.

Certainly I could not watch this in one, unbroken, session without interruption.

datasink

5 hours ago

Interesting. Can you describe why? I watched it a few times and wasn’t really impacted by it.

reissbaker

4 hours ago

As usual with Alzheimer's studies, this is another "breakthrough" in mice. Unfortunately, every other Alzheimer's breakthrough in mice has failed to replicate in humans, because... Mice don't get Alzheimer's. We can create mice with dementia patterns that are surface-level similar to Alzheimer's (beta amyloid plaques!), and clear the plaques and even often reverse the dementia. Unfortunately this doesn't help much of anything, since those diseases we create in mice are not Alzheimer's and appear not to actually be similar causally to Alzheimer's. All of them have failed to replicate and we have many of them.

I generally wouldn't trust any Alzheimer's "breakthroughs" in mice models. The models are not accurate and have thus far had zero predictive power for actual Alzheimer's in humans.

api

4 hours ago

The same is true for life extension in mice. We can massively extend the mouse life span but it doesn’t replicate in humans.

The reason there is pretty easy to grasp. Mice are a short lived more R-selected (lots of offspring, lower parental investment) species. They haven’t been heavily selected for longevity, which means there’s more low hanging fruit, more opportunities to tweak something and make a mouse live longer.

Humans meanwhile are among the longest lived large mammals and are extremely K-selected (few offspring, high parental investment). That means evolution has probably already tweaked all the easy life extension related knobs in humans. Going further will require going beyond the capacities of existing mammalian physiology, which is a lot harder. Probably possible, but requires a lot deeper of an understanding of what’s happening and more radical interventions.

latchkey

10 hours ago

There has been a bunch of studies connecting Alzheimers to HSV and now this potentially connects it back?

"Circadian cycles impact Herpes Simplex Virus (HSV) infection by influencing both the host's immune response and the virus's replication."

Update: I'm no expert in any of this. Just thinking aloud. Would love some much smarter HN community to speak up on the topic.

cjbgkagh

10 hours ago

Are we sure on the causality here? Many people get chronic fatigue from a mono infection (EBV) and chronic fatigue has a dysautonomia componenent which has a circadian rhythm component. A lot of this stuff is bidirectionally related, forming a reinforcing loop.

kakacik

10 hours ago

What about heredity of some types of Alzheimer?

anon84873628

9 hours ago

What you'll see repeatedly in the comments on articles like this is that Alzheimer's is more of a shared endpoint of many different root causes. Usually one person is complaining that the research is focusing on the wrong cause, or only treating symptoms, or misrepresenting the problem, etc etc. While other are defending it is important incremental understanding within one part of a very large space. (Oh and don't forget the people complaining about mouse research in the first place).

What I'm learning from these articles is that Alzheimer's results when certain processes fail and negative feedback loops begin. That could be due to a genetic issue (and thus is heritable as you mention), or an immune response (and thus correlated with HSV infection), a toxin, a sleep disorder, whatever. In some cases disrupting the loop maybe be enough to restore function. In others we need to understand the unique root causes. There are many areas to explore and disentangle.

bookofjoe

6 hours ago

The Genetics of Alzheimer Disease (2012) https://pmc.ncbi.nlm.nih.gov/articles/PMC3475404/

New insights into the genetic etiology of Alzheimer’s disease and related dementias (2022) https://www.nature.com/articles/s41588-022-01024-z

The complex genetic architecture of Alzheimer's disease: novel insights and future directions (2023) https://www.thelancet.com/journals/ebiom/article/PIIS2352-39...

Towards cascading genetic risk in Alzheimer’s disease (2024) https://academic.oup.com/brain/article/147/8/2680/7685999