Specific Gut Bacteria Transfer Alzheimer’s into Previously Healthy Animals

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Using gut microbiota transplants, an international team of researchers has shown memory impairments in humans with Alzheimer’s can be passed on to young, healthy rats. This confirms that gut bacteria are involved in causing Alzheimers. Specific bacteria in the gut are directly linked to cognitive decline in Alzheimer’s patients.

Gut microbiota actually play a causal role in the development of symptoms of the devastating disease.

Human participants, including 69 with Alzheimer’s disease and 64 healthy controls, donated blood for research, with some from each group also providing gut microbiota via stool samples.

Gut microbiota from Alzheimer’s patients was transplanted into 16 young adult rats whose microbiomes had been depleted by antibiotics for a week. A matching group of 16 rats received gut microbiota from humans in the healthy control group.

At least 10 days after the transplants, the rats were subjected to behavioral tests designed to evaluate memory performance as well as other traits associated with Alzheimer’s disease.

Rats that had microbiome transplants from Alzheimer’s patients showed impaired memory behaviors, particularly those that rely on a process called adult hippocampal neurogenesis.

Hippocampal neurogenesis creates new neurons in the hippocampus, a region of our brains that’s important for memory and mood, and one of the first areas impacted by Alzheimer’s.

Brain Journal -Microbiota from Alzheimer’s patients induce deficits in cognition and hippocampal neurogenesis

Alzheimer’s disease is a complex neurodegenerative disorder leading to a decline in cognitive function and mental health. Recent research has positioned the gut microbiota as an important susceptibility factor in Alzheimer’s disease by showing specific alterations in the gut microbiome composition of Alzheimer’s patients and in rodent models. However, it is unknown whether gut microbiota alterations are causal in the manifestation of Alzheimer’s symptoms.

To understand the involvement of Alzheimer’s patient gut microbiota in host physiology and behavior, we transplanted faecal microbiota from Alzheimer’s patients and age-matched healthy controls into microbiota-depleted young adult rats.

We found impairments in behaviours reliant on adult hippocampal neurogenesis, an essential process for certain memory functions and mood, resulting from Alzheimer’s patient transplants. Notably, the severity of impairments correlated with clinical cognitive scores in donor patients. Discrete changes in the rat caecal and hippocampal metabolome were also evident. As hippocampal neurogenesis cannot be measured in living humans but is modulated by the circulatory systemic environment, we assessed the impact of the Alzheimer’s systemic environment on proxy neurogenesis readouts. Serum from Alzheimer’s patients decreased neurogenesis in human cells in vitro and were associated with cognitive scores and key microbial genera.

Our findings reveal for the first time, that Alzheimer’s symptoms can be transferred to a healthy young organism via the gut microbiota, confirming a causal role of gut microbiota in Alzheimer’s disease, and highlight hippocampal neurogenesis as a converging central cellular process regulating systemic circulatory and gut-mediated factors in Alzheimer’s.

17 thoughts on “Specific Gut Bacteria Transfer Alzheimer’s into Previously Healthy Animals”

  1. This doesn’t prove much unforunately as mouse models of Alzheimers are notoriously bad. In fact no good animal model of the disease is avavilable, which is stunting research into a treatment.

  2. Look at the outstanding benefits of this particular type bacteria. You can get this stuff and make yogurt with it.

    https://web.archive.org/web/20220223191740/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3879365/

    Where I heard about it.

    https://web.archive.org/web/20211207032649/https://blog.undoctored.com/stay-40-years-old-next-40-50-60-years/

    Here’s a link to his articles on the bacteria. L. reuteri. This is the second page where he has recipes to ferment it to make more.

    https://web.archive.org/web/20211023084445/https://blog.undoctored.com/tag/reuteri/page/2/

  3. Both Alzheimer’s and other forms of dementia need a lot of funding. I had a family member with dementia (we didn’t have time to get a diagnosis as to whether it was Alzheimer’s or one of the other conditions because her health went downhill quickly from multiple factors) whom I was the primary caregiver for with the help of extra-mural nursing. Dementia is a heartbreaking condition. Add in a mild case of pneumonia or a bladder infection and it goes from moderate to debilitating spells of delirium. Awful to watch.

  4. Hopefully they will complete the study by seeing if they can reverse the symptoms with another fecal transplant, or antibiotics and another transplant.

    Then replicate.

    Then quickly move to trying the treatment on human Alzheimer’s patients in double blind studies. It’s very suited because it would be simple to give control patients their own fecal samples back for a control.

    This sort of good basic science is what showed that stomach ulcers were not a complicated multifactorial stress caused condition as was universally believed but a specific bacterial infection.

    • That good basic science was a doctor taking a risk by infecting himself with H.pylori and treating it.
      Hats off to him

  5. I don’t buy it. If bacteria could be transferred to adult rats and 10 days (!) later they begin *exhibiting Alzheimer’s symptoms*, we are talking about a truly profound level of causality. This size of effect would already be evident in natural experiments among humans.

    And by transferring either gut bacteria OR injecting serum from Alzheimer’s patients into rats you see dramatically reduced levels of neurogenesis? Via what plausible mechanism.

    • Gut Microbiome Communication: The Gut-Organ Axis

      Gut bacteria secretions have effects through the whole body. Why is this surprising? Remember, most drugs don’t have to be injected to effect us, is it shocking our intestinal bacteria might be “drugging” us to some degree?

      What’s probably happening is that people start out with a good set of bacteria, but at some point you’ll sometimes get a negative mutation in one of the bacteria that has negative health effects through some secretion.

      Now, babies start out without those gut bacteria, and acquire them from the environment. But the population the get is moderated by complex sugars in breast milk; Quite a bit of the content of breast milk is actually destined to nurture the correct bacteria, not feed the baby!

      I wonder if some dietary modification to copy that effect of breast milk might be health prolonging?

      • Fecal transplants really are worth adding to the current range of anti-aging therapies that are being researched. While it would be no silver bullet, it’s quite possible that a good deal of aging symptoms are due to intestinal flora gone bad, just resulting in a general low level toxicity.

      • Yep. They absorptive part of the mocrovilli, the lacteals are VERY superificial. We are talking about a few strands of collagen between the gut bacteria and them.
        Easy to see that their endotoxins can cross it because they do all the time in disease

      • Babies acquire their initial dose of gut bacteria during passage through the vaginal canal and directly from breastfeeding. It’s not just the sugars in the milk, there are bacteria in there as well (and also on the mother’s skin). I’ve also read that one of the beneficial side effects of most babies being born facing the mother’s spine, is increased exposure to the mother’s gut bacteria during the birth process.

      • The rapidity of response after transplantation and the report that transferring serum also causes Alzheimer’s symptoms suggests that the bacteria are producing a compound that is absorbed into the bloodstream that *causes Alzheimer’s*.

        It simply isn’t plausible that such a simple, rapid mechanism is the cause of Alzheimer’s. It always helps to ask, “if this were true, what else would be true?”

        -No Alzheimer’s patients have been cured or had the disease progression halted so far by unrelated fecal transplants or antibiotics.

        -Blood transfusions have not been shown to lower cognitive ability in humans

        -There are no other toxins or molecules that have this sort of specific effect on human or animal neurogenesis or cognition. Why not?

        I could go on almost indefinitely. This paper is making a very strong claim on pretty weak evidence.

        • “No Alzheimer’s patients have been cured or had the disease progression halted so far by unrelated fecal transplants or antibiotics.”

          Seriously, you could have said the same of ulcers. It wasn’t true, but nobody was noticing the correlation. It’s not like if a bacterial toxin caused Alzheimer’s, and you took it away, the victim would instantly recover; The brain recovers VERY slowly from damage. And uneven progress in Alzheimer’s symptoms is scarcely unheard of.

          “Blood transfusions have not been shown to lower cognitive ability in humans”

          Again, we don’t actually know this is true. You don’t generally get blood transfusions unless you’re in medical trouble anyway, which provides plenty of excuses for any impact on cognitive ability, and most blood donors are too young to have Alzheimer’s anyway. So this isn’t really good proof either.

          “There are no other toxins or molecules that have this sort of specific effect on human or animal neurogenesis or cognition. Why not?”

          Say what??? I’m just going to leave it at that, the range of effects plant and mycotoxins alone have is huge.

          I wouldn’t say at this point that the theory is proven, but it’s not as implausible as you make it out to be, and there’s certainly enough evidence here for further study.

  6. First ulcers, and now this.

    I wonder how many government hoops a stool transplant company would have to jump through to start opening clinics? It seems like the sort of thing that would be easily implemented, and be scalable.

    • It’s called a fecal transplant. The procedure is already used for some infections, and may be used by some athletes for performance.

      Or just get a month of antibiotics and use probiotics to rebuild your own hopefully better microbiome.

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