Can the bacteria in your gut explain your mood?

[PyramidHead]

From the New York Times:

http://www.nytimes.com/2015/06/28/magazine/can-the-bacteria-in-your-gut-explain-your-mood.html?_r=0

Until he joined his colleagues at Cork 10 years ago, Cryan thought about microbiology in terms of pathology: the neurological damage created by diseases like syphilis or H.I.V. ‘‘There are certain fields that just don’t seem to interact well,’’ he said. ‘‘Microbiology and neuroscience, as whole disciplines, don’t tend to have had much interaction, largely because the brain is somewhat protected.’’ He was referring to the fact that the brain is anatomically isolated, guarded by a blood-brain barrier that allows nutrients in but keeps out pathogens and inflammation, the immune system’s typical response to germs. Cryan’s study added to the growing evidence that signals from beneficial bacteria nonetheless find a way through the barrier. Somehow — though his 2011 paper could not pinpoint exactly how — micro-organisms in the gut tickle a sensory nerve ending in the fingerlike protrusion lining the intestine and carry that electrical impulse up the vagus nerve and into the deep-brain structures thought to be responsible for elemental emotions like anxiety. Soon after that, Cryan and a co-author, Ted Dinan, published a theory paper in Biological Psychiatry calling these potentially mind-altering microbes ‘‘psychobiotics.’’

I would not be surprised if it turned out that bacterially secreted neurotransmitters and other signaling molecules play a role in how we respond to stress and anxiety. So far, the only studies have been performed on animals:

Two years ago, Mazmanian published a study in the journal Cell with Elaine Hsiao, then a graduate student and now a neuroscientist at Caltech, and others, that made a provocative link between a single molecule and behavior. Their research found that mice exhibiting abnormal communication and repetitive behaviors, like obsessively burying marbles, were mollified when they were given one of two strains of the bacterium Bacteroides fragilis.

The article doesn't provide any links to the original research, so I initially suspected it was a qualitative study in a minor journal, but it's actually a pretty nice article published in Cell (bolding mine):

http://www.sciencedirect.com/science/article/pii/S0092867413014736

Consistent with the role of GI microbes in regulating intestinal permeability and metabolic homeostasis (Nicholson et al., 2012 and Wikoff et al., 2009), we show that B. fragilis treatment corrects MIA-associated changes in specific serum metabolites that appear to have a gut origin, suggesting B. fragilis may prevent leakage of harmful molecules from the GI lumen. In a proof-of-concept test of the this hypothesis, we reveal that the microbially-modulated metabolite 4EPS, which is elevated in the circulation by MIA and restored by B. fragilis treatment, is sufficient to induce anxiety-like behavior in naive mice. These data indicate that metabolomic changes contribute to the onset and/or persistence of autism-related behavioral abnormalities.

<snip>

We propose the transformative concept that autism, and likely other behavioral conditions, are potentially diseases involving the gut that ultimately impact the immune, metabolic, and nervous systems, and that microbiome-mediated therapies may be a safe and effective treatment for these neurodevelopmental disorders.

Thoughts?

 

[Peez]

Can the bacteria in your gut explain your mood?

I don't know, I have never asked them.

Peez

 

[Malintent]

completely feasible. I like the term "Psycobiotics". Bacteria secrete all kinds of substances... why not one that has a psychoactive effect? especially with bacteria that evolved with the selection pressures of a human intestine. Yeast secrete alcohol.

Just think of all the naturally occurring psychoactive substances that exist today commonly (psychoactive mushrooms, cannabis, um... cannabis..)

 

[ronburgundy]

Interesting. So, an obvious follow-up issue is how diet impacts mood via its impact on the number, type, and "actions" of these gut flora.

 

[PyramidHead]

Interesting. So, an obvious follow-up issue is how diet impacts mood via its impact on the number, type, and "actions" of these gut flora.

Yes. My therapist is a big proponent of that kind of approach. It's strange to consider the implications for personal identity and mental independence. Less than a century ago, people with clinical depression or anxiety disorders were told to simply buck up and get with the program. In recent decades, such people have been prescribed medication that affects the chemical environment of the brain. The shame associated with having a mental disorder has certainly decreased, but the underlying concept that something about your brain is defective still has a social stigma attached to it. Many people with mental disorders feel ashamed about being the kind of person who struggles with social activities, when other people seem to have no difficulty navigating the social sphere. I wonder, if this research becomes mainstream, how that perception will change. If it turns out that a clinically depressed individual is not someone whose brain is wired differently, but someone whose intestinal occupants are out of balance, would mental disorders become as socially acceptable as bacterial infections? I imagine hardly anybody feels ashamed about getting a sinus infection, but plenty of people harbor a sense of personal inadequacy as a result of chronic anxiety or depression. If the root cause (or at least a major contributing element) were found to be the composition of microorganisms hanging around in my gut, rather than a defect in my mind, maybe that sense of inadequacy would be lessened.

Going a little further, if the psychobiotic hypothesis is validated, it means many of the characteristics people normally ascribe to their sense of self--personality, temperament, introversion, risk-taking, maybe even the precursors to belief--are at the mercy of colonies of tiny organisms living in our feces. Some may find that a troubling thought. I actually think it's kind of nice to feel less like a disconnected and insular being, when I am more like an Ellis Island of ancient lifeforms whose total genome is many orders of magnitude larger and more diverse than that of "my" cells.

 

[Perspicuo]

Actually it sounds like instead of your interpersonal situations controlling your moods, your gut tenants do. Well, not exactly.

The truth is gut flora mediate between interpersonal stressors and resultant mood and behavior. For example, if you have irritable bowel syndrome, stress makes your secretions change, making your gut flora proportions change and what they do too, and then your moods change --both becuase of the irritable bowel and because of enteric nervous system phenomena.

Did you know you more than 95% of the serotonin your body uses is by the neurons in the ENS, not your CNS? (Also roughly 50% of the dopamine). The ENS uses as many neurotransmitters (more than 30) as your CNS?

High school textbooks taught us the nervous system was divided in CNS (central) & PNS (peripheral), and the PNS itself was divided between ANS (autonomic) and SNS (somatic). Things have changed. PNS = ANS+SNS+ENS. Neurologists call it the "second brain" (perhaps an exaggeration due to the novelty of the subject).


We must understand science journalism is a business. They thrive on article views, and so click-worthiness is bread on the table. Be wary.

Emotions are very complex. We are now learning that the ENS is part of the story too. The moral of the tale you can take with you is: What you do to your gut, including what you eat, can powerfully alter your moods. How much, how far, we don't know yet.

 

[ronburgundy]

Actually it sounds like your interpersonal situations don't control your moods, but whether your gut tenants are having a party or what you fed them.

The truth is gut flora mediate between interpersonal stressors and resultant mood and behavior. For example, if you have irritable bowel syndorme, stress makes your secretions change, your gut population proportions change and what they do too, and then your moods change --both becuase of the irritable bowel and because of enteric nervous system phenomena.

Given what we already know about how diet changes gut flora, it would imply that gut flora mediate not only the mood effects of environmental stressors, but also trigger mood effects due simply to whether you ate some yogurt, independent of stressors. IOW, gut flora can be a common mood-impacting mechanism for otherwise independently varying environmental stressors and diet.

If it turns out that a clinically depressed individual is not someone whose brain is wired differently, but someone whose intestinal occupants are out of balance, would mental disorders become as socially acceptable as bacterial infections?

Let's not get too far ahead of the actual science. Much of what happens in therapist offices has little basis in science. The cited research is only talking about "mood" fluctuations that are within modest and "normal" ranges of day to day fluctuations for most people. Clinical disorders (like depression) usually mean the persons is going to extreme levels outside those normal ranges, often processing info in qualitatively different ways, etc..
There is a plausible role for diet in particular manifestations of symptoms due to clinical conditions, but the notions that the conditions themselves are rooted in diet impacted gut flora is a huge leap beyond what the science implies and what is likely in most cases.

 

[4321lynx]

Interesting. So, an obvious follow-up issue is how diet impacts mood via its impact on the number, type, and "actions" of these gut flora.

This is the stuff of people like Dr Perlmutter and his latest book *Brain Maker* And diet he deals with in his *Grain Brain*. He is a trained neurologist who now practices what he preaches, he says. He is pretty radical but quotes some good work by others. Google his name and you'll find lots of links. \\\\\\\note that he probably is making a packet of money with his supplements , books, lectures etc

 

[Perspicuo]

Given what we already know about how diet changes gut flora, it would imply that gut flora mediate not only the mood effects of environmental stressors, but also trigger mood effects due simply to whether you ate some yogurt, independent of stressors. IOW, gut flora can be a common mood-impacting mechanism for otherwise independently varying environmental stressors and diet.

It depends on what you mean by "trigger". I suspect (strongly) we don't know what it means yet --in other words, how much, how far, how long, what is the feedback course (gut to CNS via ENS via CVS neurotransmitters or other pathway [such as lymphatic CVS]? ENS to CNS and back? What role does the Vagus have if at all?,etc). Science on the frontiers is a continual debate. That's the exciting part of it all.

 

[Speakpigeon]

Thoughts?

No, bacteria is not the explanation for our moods but what goes on inside our stomach and gut can definitely have an effect on our moods, in particular the choice of food (and drink) you last had, which presumably will affect the bacteria in the gut. It's even conceivable that some bacteria have some control over the behaviour of their host, in particular over what we eat.
Just thoughts...
EB