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Microbial Brain Transplant?

November 29, 2011

In the decade since Brain Plague, extraordinary revelations have come out on how microbes control the mind. A recent article in PNAS reports how Lactobacillus bacteria in the digestive tract of mice decreased stress and anxiety behaviors. The bacteria were associated with increased neurotransmitter expression in the hippocampus area of the brain, among other brain effects. But how could digestive bacteria affect the brain? The effect actually involves the vagus nerve, a major nerve that connects the digestive tract with the brain.

If bacteria can control rodent behavior, why not humans? The brain regions involved affect memory and learning as well as mood.  Other microbes, such as the parasite Toxoplasma, are suspected of controlling human brains ways that encourage spread of the parasite–with possibly more horrific effects. (Caveat, the last source is new to me; perhaps Paws4thot knows if it’s any good?) Data on toxoplasmosis are taken seriously by researchers, as are the possible connections with schizophrenia.

But intestinal bacteria are our friends–actually, part of us. For all we know, we’ll find out that intestinal bacteria are a normal “part of our brain,” just as fecal bacteria are part of our intestine. Last summer at Renovation I reported on fecal transplant, a miracle cure for C. diff and ulcerative colitis. Next, will we be treating psychiatric disorders with gut bacteria?

  1. SFreader permalink
    November 30, 2011 10:46 am

    How would this lactobacillus research information relate to lactose-intolerant individuals – is there some other mechanism/but that their bodies rely on or are such individuals typically more stressed out?

    Considering that a large chunk of the Western population is 50+ and actively encouraged to both have a colonoscopy regularly (i.e., thoroughly clean out their guts) as well as to monitor their blood pressure, this lact.B research suggests that the medical community needs to sort out their public health messages and be more mindful of such confounding effects.

    • November 30, 2011 8:18 pm

      Lactobacillus means bacteria that produce lactic acid. They do not have to do with lactose, so they would not be a problem for lactose-intolerance. Some lactobacilli are involved in making yoghurt and cheeses.

      The colonoscopy “cleanse” is an interesting question. There is some anthropological evidence suggesting that occasional cleanout of the intestines is helpful. But the cleanse for colonoscopy may allow overgrowth of dangerous “fringe” members of the microbial community. On balance, a colonoscopy once in ten years is worth it to test for cancer. But tor the elderly, with impaired immune systems, it is questionable to have colonoscopy unless you have a history of colon disease. Anyway, this is what I see in the literature; not qualified for medical advice.

  2. Alex Tolley permalink
    December 1, 2011 9:54 am

    Would a fecal transplant have an effect on the mind. beyond the direct effects of feeling better? That might be important if the technique becomes widespread. Just how strong is the effect of gut bacteria on mind, and are the few major types of gut flora ecologies telling us something fundamental about human behavior?

    • December 1, 2011 10:04 am

      That’s a *fascinating* question. While it’s clear that only certain microbial communities are good for the colon, it isn’t just one mix–thousands of different mixtures of species can work. After fecal transplant, the donor and recipient become “fecal twins”–sharing the same colon biota signature.

      So maybe it does offer a new mode of mind control, or at least mood control. I see the making of a whole new novel here.

      • December 1, 2011 11:08 pm

        You could have some fun crossing Like Water for Chocolate with the discoveries of a microbiologist looking for love…. If you’re really feeling creepy, have a cat around, too.

  3. December 1, 2011 11:07 pm

    Umm, if we’re talking about Lactobacillus bulgaricus, can I strongly recommend eating yogurt, instead of a fecal transplant? It’s a lot cheaper. If you’re really cheap (like me) you can even invest in the $50 Lactobacillus incubator/yogurt maker and get the cost way down.

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