New research links potentially toxic fat-protein complexes to Alzheimer's
medicalnewstoday.com
medicalnewstoday.com
This paper looks really good.
Amyloid beta has long been implicated in Alzheimer's. Now they've found a way to trigger the disease by generating amyloid in the liver and shown that it can reach the brain (by crossing the blood brain barrier). This setup was shown to trigger the disease. It's a very plausible mechanism that worked end-to-end and seems to fit all of the observational evidence we've gathered.
The paper: Synthesis of human amyloid restricted to liver results in an Alzheimer disease–like neurodegenerative phenotype
https://journals.plos.org/plosbiology/article?id=10.1371/jou...
Abstract:
> Several lines of study suggest that peripheral metabolism of amyloid beta (Aß) is associated with risk for Alzheimer disease (AD). In blood, greater than 90% of Aß is complexed as an apolipoprotein, raising the possibility of a lipoprotein-mediated axis for AD risk. In this study, we report that genetic modification of C57BL/6J mice engineered to synthesise human Aß only in liver (hepatocyte-specific human amyloid (HSHA) strain) has marked neurodegeneration concomitant with capillary dysfunction, parenchymal extravasation of lipoprotein-Aß, and neurovascular inflammation. Moreover, the HSHA mice showed impaired performance in the passive avoidance test, suggesting impairment in hippocampal-dependent learning. Transmission electron microscopy shows marked neurovascular disruption in HSHA mice. This study provides causal evidence of a lipoprotein-Aß /capillary axis for onset and progression of a neurodegenerative process.
We knew amyloid beta was highly associated with Alzheimer's. We've been studying this for decades.
The researchers noticed amyloid beta was found in lipoprotein complexes (fat+protein), then experimentally modified the liver to produce it. The protein leaks out of the liver and causes neurodegeneration.
> Insight into how blood Aβ increases risk for AD comes from findings that in humans, greater than 90% of blood Aβ1–40 and 97% of the particularly pro-amyloidogenic Aβ1–42 is associated with plasma lipoproteins [3], principally the triglyceride-rich lipoproteins (TRLs) of hepatically derived very low-density lipoproteins (VLDLs) and of postprandial chylomicrons [4,5]. Direct evidence of a peripheral TRL-Aβ/vascular risk pathway for AD comes from studies in preclinical models, which show that cerebral capillary amyloid-angiopathy, a common early neurovascular pathology of AD, may be a consequence of parenchymal extravasation of TRL-Aβ.
This implicates fatty acids originating from the liver migrating (extravasation). And they just experimentally reproduced this.
Some quotes from the linked article:
> “This study,” he added, “shows that exaggerated abundance in blood of potentially toxic fat-protein complexes can damage microscopic brain blood vessels called capillaries and, thereafter, leak into the brain, causing inflammation and brain cell death.”
> “[Changes] in dietary behaviors and certain medications could potentially reduce blood concentration of these toxic fat-protein complexes, [subsequently] reducing the risk for Alzheimer’s or [slowing] down the disease progression,” he concluded.
This would suggest that liver health and diet can play a factor in disease development.
Of course there's the chance that this is just a really good "biologically plausible" mechanism that looks good on paper, but might not naturally occur outside of this experimental setup. There will need to be much more research to either prove or rule this out.
This looks exciting though.
Reading Derek Lowe, you'd get the impression that the beta amyloid hypothesis is a formerly exciting thing of the past with a disastrous track record.
>the relentless failure in this area, when amyloid plaques seemed for so long to be the most likely causative agent for the disease, is really something that makes you question things.
>Add in the additional complete failures for every other attempt at the amyloid mechanism (secretase inhibitors, for example) and you start wondering if amyloid really is a cause of the disease or not
Now Wikipedia is more optimistic:
>The "amyloid hypothesis", that the plaques are responsible for the pathology of Alzheimer's disease, is accepted by the majority of researchers but is not conclusively established.
I'm curious to see what comes out of this study, it's a very encouraging result. But it's hard to resolve this conflict of the mechanism looking great on paper, and completely failing in trials.
The amyloid beta plaques may be not cause, but symptom of the disease. Maybe the TRL-A-betas are causing the damage, get metabolized and after that the protein separates and then accumulates in the brain? The study states, the TRL-A-beta are causing inflammation, which they attribute for disease progression rather than A-beta plaque formation.
> ...the findings presented in this study nonetheless support a now large body of evidence that demonstrates that the genesis of plaque is not the initiating trigger for neurodegenerative processes to be initiated, but rather, may be consequential. This study provides evidence that more subtle chronic interactive effects of peripheral metabolism of TRL-Aβ with the cerebrovasculature may be sufficient to potentially cause AD.
So, clearing up A-betas may be just flushing the "damage logs".
They definitely seem to lean into the neurovascular damage angle. I.e. liver produces amyloid-beta complexes, high levels of which result in neurovascular damage, resulting in lipids making it through and accreting in the brain.
Which makes sense, as if your capillaries are less functional, how would you body clear plaques from a difficult to reach organ (the brain)?
That said, amyloid is very upstream in the causal chain, which begins about 15-20 years before clinically detectable symptoms. It's believed by some (including myself) that amyloid therapy would be preventative at that early stage, but you won't do much better than a ~35% slowdown at the stage Alzheimer's is typically diagnosed. At that stage, tau therapy is more promising, since it's the more proximate cause of neurodegeneration.
For example (making this up) I don't think we have disproven that beta amlyoid build-up causes inflammation, which actually causes the brain damage via a process that continues even once the beta amyloid is gone.
Between the two outcomes (ABPs exist but there's no decline, and ABPs are removed but dementia persists), the prevailing interpretation is that ABPs alone do not cause Alzheimer's. They seem to arise along with the cognitive loss, though not cause it.
Tau deposits and associated neurofibrillary tangles have also been implicated in dementia, but also can be absent in those with the disease, so they too are not directly causal.
However, I have not heard of the opposite: people with cognitive decline and amyloid-β pathology but no tau pathology.
Once dementia sets in, there is no turning back, the neuronal network has been damaged enough and you can't replace neurons (not most of them)
Dementia is the main symptom of Alzheimer. And there are other causes of dementia, too.
To continue with your example, if beta-amyloid was a major source of inflammation, and inflammation caused the damage, it'd seem reasonable to expect that removing the plaques would result in slowed cognitive decline.
Strangely, this does not seem to happen in clinical trials.
For example, mutations in the enzymes or proteins involved in the production of amyloid-β (APP, PSEN1, and PSEN2), which structural analysis show have the direct effect of producing either more total amyloid-β, or more of amyloid-β 42 (the specific peptide implicated in Alzheimer's), deterministically cause Alzheimer's. That puts amyloid-β causally upstream at least in those cases, the so-called autosomal dominant variety, which are ~1% of Alzheimer's cases.
The remaining ~99% of cases are less straightforward to interpret, but the disease looks essentially the same as the ~1% of cases described above: first amyloid-β builds up in the default mode network, then it spreads throughout the brain, eventually reaching the medial temporal region where primary age-related tauopathy (PART) is waiting, only then does the tau pathology spread, and neurodegeneration follows the tau pathology in lockstep. The way the amyloid-β and tau proteins misfold in autosomal dominant and sporadic Alzheimer's are the same, too, even though other tau pathologies have different tau folds. So basically, there's every reason to believe sporadic Alzheimer's is essentially the same disease as the one which we're basically certain is caused by amyloid-β.
What would be some recommended changes in dietary behaviors if this link were also verified in humans?
very good primer: https://csroldsite.wordpress.com/2013/03/04/oxysterols-the-t...
I don't even disagree or something, but your advice seems rather automatic than based.
The study used atherogenic diets as offense. So all the consensus on heart health seems to apply: LDL bad; salt bad; cholesterol bad; saturated fats bad - inflammation bad.
In mice.
> We have shown that patients with AD have increased brain levels of 27-hydroxycholesterol, which may affect the production of beta-amyloid.
chicken is more susceptible to lipid oxidation than beef or pork. lower temperature cooking methods are preferable.
> In wild-type (WT) C57BL/6J mice, a saturated fatty acid (SFA)-enriched diet was found to strongly stimulate biosynthesis and secretion of TRL-Aβ, concomitant with a reduction in cerebral capillary endothelial tight junction proteins, blood-to-brain extravasation of TRL-Aβ, and marked neurovascular inflammation [6]. In contrast, mice fed unsaturated fatty acid–rich diets had no evidence of exaggerated TRL-Aβ secretion and capillary integrity was unremarkable [6,7].
...
> Moreover, synergistic effects of TRL-Aβ with exaggerated central nervous system (CNS) synthesis of human Aβ are also suggested by the findings of accelerated amyloidosis in amyloid precursor protein/presenilin 1 (APP/PS1) mice maintained on atherogenic diets [9].
Not saying keto is inherently an atherogenic diet, but surely saturated fat and salt isn't exactly avoided by most followers.
> Just do a quick Google or YouTube search, lots of content on the subject.
Yeah.......... sure. Content.
I can't find one of the more comprehensive studies I was looking at before, but a quick search pulls up this video which discusses a recent human trial which showed significant improvement on the keto diet (links to the study in description):
Consequently, it suggests someone who is already impaired due to AD may be able to improve symptoms from a keto diet (vs a low-fat one).
But the general consensus is that reversing or alleviating AD symptoms is a different task than preventing it in the first place.
The linked article here is talking more about the latter, and specifically for preventing non-hereditary AD.
I'll take a more detailed look into the other resources I've studied and post another reply in a few hours.
And nutritional research... well, there's a lot of money in food, and that's funded a lot of noise around the signals.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6720297/ - a review of various studies, concludes that "Keto diet may modulate a broad array of metabolic and signaling changes underlying the pathophysiology of neurodegenerative disorders. Based on the limited animal studies and clinical trials, keto diet has beneficial effects for enhancing mitochondrial function and cellular metabolism. It is associated with improved cognitive performance in elderly adults with Alzheimer's disease. The improvement of the cognitive outcomes depends on the level and duration of ketosis."
https://alzres.biomedcentral.com/articles/10.1186/s13195-021... - study from video I linked above, concludes that "patients on the ketogenic diet improved in daily function and quality of life".
https://academic.oup.com/advances/article/11/6/1583/5864685?... - another review, concludes that "The results underline that, collectively, the efficacy of ketogenic therapy in MCI/AD appears promising, indicating that it is more than a symptomatic remedy (137). Nevertheless, research is still scattered and heterogeneous in terms of study design, intervention, participants, and outcomes of interest."
https://pubmed.ncbi.nlm.nih.gov/15123336/ - study on MCT oil which raises levels of ketones, abstract says "Higher ketone values were associated with greater improvement in paragraph recall with MCT treatment relative to placebo across all subjects (P=0.02). Additional research is warranted to determine the therapeutic benefits of MCTs for patients with AD and how APOE-4 status may mediate beta-OHB efficacy."
Additionally Alzheimer's is actually referred to by a large number of folks in the field as "type 3 diabetes" & as far as I understand there is a large amount of overlap between the two diseases; we have studies showing that diabetes can be nearly or totally cured by carbohydrate restriction:
https://pubmed.ncbi.nlm.nih.gov/29417495/ - of 349 participants, 94% were able to eliminate or reduce insulin therapy after 1 year (57% discontinued their prescriptions entirely).
The book "The Alzheimer's Antidote" by Amy Berger is a great resource if you are open minded enough to be willing to look at informational resources once step above scientific controlled studies (unfortunately many folks are not).
The End of Alzheimer's by Dr Dale Bredesen is all about "scientific controlled studies" and comes to the same conclusion about keto diets. No need to be open-minded :)
My original comment on this thread is at -1 even though what I said was factually correct (and I found all my linked sources above via exactly what I said, a quick Google search). Another of my comments on this post has the classic reply "ah but the author of your study has been accused of quackery if I google his name".
So I'd say a bit more open-mindedness would be in order.
- 2 hard-boiled eggs for breakfast.
- 1 cup of walnuts or almonds or pecans as a snack.
- Eaten with a slice of sharp cheddar cheese (4g saturated fat).
- Always rinse the nuts to make them more palatable.
- This meal may be eaten twice a day.
- 3 tablespoons of chia seeds soaked in water, as a snack.
- Like a high fat/protein version of oatmeal.
- Peanuts and macadamia nuts as needed for hunger.
- Steamed vegetables (broccoli, kale, spinach, brussels, zuchini, tomatoes).
- Eaten with 8 tablespoons of olive oil.
- A very large serving of steamed vegetables.
- Salt/seasoning however you prefer.
- This is dinner.
Once a week, eat a cheeseburger. Or twice a week: rotisserie chicken and olive oil, or coleslaw and guacamole and chicken.This high-fat, low carb diet can be maintained with no difficulty for decades. Also, it is an ideal diet for insulin-dependent diabetics.
It's cheap, healthy, and you won't be hungry.
I’m not going to tell you anything else, because I too am a random commenter on hacker news - except please don’t take the comment as a good example of how to put together a keto diet.
I am not entirely sure that my body is ready to down half a cup of oil as part of a regular meal.
It's typical for ketogenic dieters to use vegetables as a carrier for olive oil, and for a large fraction of the day's calories to come from that oil.
OK, I have to ask...what is this about? "More palatable" in what way?
We're in sleep tech, building closed-loop SWO which of course has an impact on removal of beta-amyloids, but all the research I've seen to date has just not gone further than saying there is a "correlation" between Aß and Alzheimers.
I'm not sure this completely closes the loop on cause-effect, but it seems a very strong bit of evidence. Not sure how I missed it before, but thanks.
PS: I understand this will be pure speculation but any insights would be helpful.
The only foods which are ‘definitely safe’ are leafy greens and cruciferous vegetables. Could probably add berries to that in moderation. Not saying that is all one should eat, what I mean is to eat less of everything else than baseline, to some caloric deficit. This excludes the few people who are underweight for whatever reason, and those with certain diseases.
If you have kidney disease, or are at risk for kidney stones, oxalates from excessive leafy greens can make either condition worse.
(Metabolism (which drops with less weight) + Exercise - Intake) -> over time -> equilibrium weight.
So assuming you pick a low calorie diet for now, eventually you'd maintain at a skinny weight.. and maybe live longer. Maybe.
We are surrounded by food that has very high nutritional value. A steak or a piece of salmon or contemporary vegetarian/vegan equivalents are all calorie and micronutrient parties. Most of human evolution took place with much more limited access to nutrition.
https://www.kxan.com/news/simplehealth/dirty-dozen-which-fru...
I'm sure if you do five whys on liver malfunction, you'll always be able to find that diet impacts structurally deficient organs eventually, but wether or not it is a significant contributor is always up for debate.
This is a potential mechanism that they've experimentally built and triggered. There's no guarantee this happens in situ exactly as they've set up. There's also the chance that Alzheimer's is caused by various contributing factors.
This paper does look promising though, because they've triggered the disease from the liver using lipoproteins that have been observed.
I'd love for domain experts to weigh in.
My guess is healthy diet and exercise go a long way. Don't drink and avoid sugar (diabetes) both of which are damaging to the liver.
For example: https://amosinstitute.com/cognitive-health-program/
https://www.nia.nih.gov/news/study-reveals-how-apoe4-gene-ma...
the mechanism could be atherosclerosis https://youtu.be/t-noCw4LsY4?t=168
linear correlation by country https://youtu.be/Gel4vlG4Jbk?t=68
personally, i think something close to wfpb diet is the best for all things (except gaining weight).
Reduce fat intake.
It's not the cause, but the carrier of toxins across the blood-brain carrier. Reducing fat would reduce the rate of toxin build up. It's not a cure, nor does it tackle the genetic component, but way to prolong lifestyle.
https://pubmed.ncbi.nlm.nih.gov/29701155/
https://www.nature.com/articles/s41598-020-65908-y
But can't say I've been following Youtube videos or Reddit on the matter.
Edit: I didn't know who the youtube video you linked is, but a cursory google bring up that he is accused of quackery. Also, the source on that video is... his own website hosting his own work. Not exactly peer review is it?
You can check my other comment above for a bunch of other sources/studies on keto diets reversing Alzheimer's symptoms if you'd like.
https://www.statnews.com/2021/10/11/mouse-experiments-with-o...
https://www.nia.nih.gov/news/study-reveals-how-apoe4-gene-ma...
It's also very suggestive that Vitamin D deficiency is associated with reduced choline metabolism in the brain: https://pubmed.ncbi.nlm.nih.gov/3753932/
Mice don’t get alzheimer’s.
People with Alzheimer have been cured after taking antibiotics.
Their conclusion: "Many experimental data support the involvement of a polymicrobial community in the pathogenesis of AD."
The authors do NOT claim that anyone has been cured of dementia by reducing inflammation or altering patients' microbiome. They suggest only that the microbiome and its role in inflammation may be worth further investigation.
It would be very optimistic to imagine that an antibiotic therapy may be administered and cure, or at least prevent progression of AD. It is clear, however that no antibiotic regimen has been developed to cure periodontitis which has a similar implication of chronic infectious microorganisms and biofilms.Just google ‘alzheimer's infection theory’ if you want to dig deeper.
I'm starting to think the causes can be multi-variate.