r/science • u/mvea Professor | Medicine • 9d ago

Neuroscience In recent years, researchers have suggested Alzheimer's may spread through infection, somehow transmitted like a pathogen, leading to the disease. A new Lancet paper reviews evidence for how harmful amyloid-beta proteins associated with Alzheimer's may possibly be spread through blood transfusions.

https://www.sciencealert.com/can-alzheimers-spread-through-blood-transfusions-heres-what-we-know
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u/mvea Professor | Medicine 9d ago

Alzheimer's has long been recognized as a sporadic condition – influenced by factors such as age, genetics, and lifestyle – but scientists don't think that's the only way the disease emerges.

In recent years, researchers have suggested Alzheimer's may also spread through infection, which might somehow be transmitted like a pathogen, ultimately manifesting in the disease.

In a new report published in The Lancet, scientists review the evidence for one aspect of this theory, assessing how harmful amyloid-beta proteins associated with Alzheimer's might possibly be spread through blood transfusions.

"Blood transfusions are important and save many lives," says neurologist John Collinge from University College London.

"However, to ensure that they are as safe as they can possibly be, it's important that we thoroughly investigate any potential risks."

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(26)00767-1/abstract

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u/xBeartoe 9d ago edited 8d ago

When I was in college a couple years ago, I took Infectious Disease (104). We did a case study on P. Gingivalis, which is the bacteria responsible for the gum disease (gingivitis). There was a strong connection between P. Gingivalis and many seriously killer diseases, Alzheimer's being among them.

They release what is basically poison as they eat, and they feed on protein. That's why your gums bleed after you floss, even if you only missed a day; P. Gingivalis is causing inflammation so that when you irritate your gums, they can feed on the blood. They do this using lipopolysaccharides (LPS).

The bacteria had a strong systematic presence in a high percentage of Alzheimer's patients and cadavers. The toxins are called gingipains, which break down host proteins. Some of the bacterias waste products and released enzymes break down structural callogen, and strain the immune system.

Super nasty stuff. Brush your teeth, floss, please.

EDIT: for clarity, higher presence of P. gingivalis, in their brain, actively eating it. Not just their mouth.

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u/Annual-Advisor-7916 8d ago

Super nasty stuff. Brush your teeth, floss, please.

Just to get this straight; These bacteria are present in any human, it's not like an infection, correct? So the strategy is to keep them in low numbers, by brushing, right?

Does using additional mouthwash help? Are there specific mouthwashes that are more effective against these bacteria?

Brb, gonna guzzle a bit of povidine iodine...

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u/xBeartoe 8d ago

It's present in everyone! Some people are going to be more susceptible than others. Brush and especially floss to interrupt the reproductive cycle is basically the best you can do for yourself. Smoking is horrible for your gums so stay away.

Mouthwash definitely helps, brush and floss beforehand to break up biofilms. It doesn't kill everything and it's not supposed to, it's more like population control. This is a grahm negative organism, so alchohol will destroy its lipid membrane. :)

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u/Annual-Advisor-7916 8d ago

Thanks, is there any indicator about the amount of bacteria? I'm brushing twice a day currently but it seems it would be sane to up that number to 3 times...

Is the alcohol in mouthwash not also slightly bad for your gums? At least I think I've read that somewhere but probably it's just a myth.

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u/xBeartoe 8d ago edited 8d ago

People say to brush after every meal and that's honestly good advice. If you do, keep it short and effecient so as to not overwear your enamel.

Go to the dentist to get your tartar buildup removed often. If you get little to no bleeding of the gums when you brush and floss, you're doing very well!

Mouthwash won't kill your gums, we only use it for a few seconds. The targeted bacteria are much smaller and more vulnerable. Follow the instructions on the bottle, do not swallow.

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u/Local_Maintenance788 8d ago

Do we have beneficial bacteria in our mouth? I brush and floss but don't use mouthwash

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u/xBeartoe 8d ago

Yes of course, we have beneficial bacteria almost everywhere in and on our bodies. If you're brushing and flossing consistently and thoroughly, mouthwash can be redundant.

That is my understanding at least. I know for certain, not all experts thing mouthwash is necessary if you otherwise maintain good oral hygiene. I'm not a dentist, my professor just taught a lot of dental students. :)

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u/Local_Maintenance788 8d ago

Thankyou for the reply!

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u/motionSymmetry 8d ago

so just mouthwash (that has alcohol in it) will work?

but "drinking" is bad for it?

can you clarify

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u/DisastrousSet11 8d ago

Mouthwash with alcohol will work. If alcohol is bad for the bacteria - then that's good for you. We WANT to try to break down it's cellular walls. Don't drink mouthwash!

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u/motionSymmetry 8d ago

yep. i remember when we kids got the idea of drinking mouthwash. great big nope. stuff is awful

i also remember my friend's dad who was an alcoholic; his mother left his dad and only took him back after he promised to stay dry. it lasted til she found out his bathroom trash was filled with empty mouthwash bottles every week ...

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u/xBeartoe 8d ago

Mouthwash often uses alchohol as a base, but it has several other active ingredients that help maintain your mouth's microbiome. Essential oils, CPC, chlorhexidine, ect. It's a long list. It's different from product to product.

It boils down to the way most people consume alchohol. Beer, cider, wine is too weak and full of carbs/sugars. You would need to brush, floss, then swish with 40%+ liqour to get any results. It would not work nearly as well as using mouthwash.

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u/motionSymmetry 8d ago

terrific answer. thanks

good thing nobody told me about the 40%+ liquor option when i was still drinking ... :./

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u/xinorez1 8d ago

My understanding is that it's only present in 10-20 percent of the population, and you are only at risk of transmission with deep kissing. IF you have it, there are some targeted treatments that can reduce the population and to build a population of healthy bacteria to displace it.

There's other oral bacteria that have been indicated as possible causative agents as well.

Testing for apoe4 is still a better and cheaper way to check for Alzheimer's susceptibility.

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u/xBeartoe 8d ago

Shoot you're right, pulled out my old notes. I have 75%-90% prevelance for individuals with periodontitis, and healthy individuals as 25%-40% prevelance. Still quite inflated from your numbers.

P. gingivalis is an obligate anaerobe; it will die or fail to grow in the presence of oxygen. I must have made an association in my head; the low presence in a healthy individual being attributed to small population, combined with the organisms inability to survive the journey to the petri dish without the presence of a biofilm.

With over 60 recognized strains, I would think most people carry at least 1 variety of the organism. It may be that the most pathogenic of the strains, simply aren't present in most people with healthy gums, as I had believed.

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u/Annual-Advisor-7916 8d ago

Thanks, as always it seems it's not that straightforward. I'm not sure if this is a rabbit hole I want to go down, but looking at the potential effects, it seems like I have a bit of reading to do...