Could mood disorders have a bacterial origin?
Those microbes of yours perform some truly extraordinary feats.
Right now, for example, several pounds of bacteria in your gut are helping you digest food and process vitamins. Thanks guys.
But that’s just the tip of the iceberg.
You see, many researchers suggest that alongside plenty of other aspects of health, your microbiome has a profound effect on the way your mind works.
Low levels of certain species of bacteria in your gut could be associated with depression or anxiety. There could even be a connection between the microbiome and autism.
Maybe we shouldn’t be quite so surprised about the gut-brain connection though.
Consider neurons, for example. Your brain has around 100 billion of them, but I wonder if you knew that your alimentary canal, that 27-meter tube winding its way from your mouth to your rear end (yup, it’s a long way down), has another 100 million or so neurons embedded in its walls.
That’s right, the idea of a ‘gut feeling’ contains more than a grain of truth.
And those neurotransmitters, the chemicals which can play a big part in emotion: 50% of your dopamine and 95% of your serotonin isn’t in your brain. It’s in your gut.
Back to bacteria, though. Let me tell you very briefly about three quite remarkable studies.
In 2011 a team of Irish and Canadian scientists found that mice which were dosed with Lactobacillus rhamnosus (a bacterium found in probiotic yogurt) and then dropped into a tank of water from which there was no escape, took longer to give up in despair than a control group that didn’t have the bacteria.
In fact the L. rhamnosus mice behaved in the same chilled-out, relaxed way that mice given antidepressants like Zoloft and Prozac did.
Because they tend to respond to stimuli in similar ways to humans, mice are frequently used in laboratory experiments. When you learn something from mice there’s a pretty good chance you’ll find the same thing in humans.
However, another study – at UCLA – involved 25 human subjects.
For four weeks, twelve people ate a cup of commercially-available probiotic yogurt twice a day, while the remainder were given a non-probiotic dairy product.
Before and after the four weeks, all were given fMRI brain scans during which they were shown images of human faces expressing emotions such as anger or fear.
The brain scans showed the people in the control group were more affected by these emotional triggers than the probiotic yogurt eaters, who by comparison were calmer and less stressed.
Returning to mice, a third study – at the California Institute of Technology – focused on a microbe called Bacteroides fragilis, an absence of which is often observed in the guts of people with autism.
By transplanting B. fragilis from human donors into the guts of mice with symptoms similar to autism, they found the rodents exhibited less anxiety-like behavior, interacted more with other mice, and also behaved less repetitively.
This mood-microbiome connection is pretty new and revolutionary, and it’s an area that seems ripe for self-experimentation:
1) Measure and track your mood for a while
2) Have your microbiome tested
3) Introduce new species of bacteria (by eating them)
4) Explore how this has affected your mood via your tracking, and your microbiome via a second test.
Such a promising area. You see, in any given year almost 10% of U.S. adults experience mood disorders. Many are prescribed medication.
What if bacteria could really offer an alternative to pharmaceuticals?
Have a great week!
Director of Product, Community, and Growth
Some further great reading:
Can the Bacteria in Your Gut Explain Your Mood?
When Gut Bacteria Changes Brain Function
Consumption of Fermented Milk Product With Probiotic Modulates Brain Activity
Think Twice: How the Gut’s “Second Brain” Influences Mood and Well-Being