Anxiety and depression aren’t “just in our heads,” as they say–apparently, they’re also in our guts.
Gut bacteria play a large part in our health. The contents of that microbiome affect digestion, of course, but we’re increasingly discovering that they also affect allergies, obesity, cancer, and quite possibly mental health.
The Atlantic has an interesting article on the topic, exploring the link between gut bacteria like lactobacillus and bifidobacterium and anxiety, autism and depression.
Scientists have also gathered evidence that gut bacteria can influence anxiety and depression. Stephen Collins, a gastroenterology researcher at McMaster University in Hamilton, Ontario, has found that strains of two bacteria, lactobacillus and bifidobacterium, reduce anxiety-like behavior in mice (scientists don’t call it “anxiety” because you can’t ask a mouse how it’s feeling). Humans also carry strains of these bacteria in their guts. In one study, he and his colleague collected gut bacteria from a strain of mice prone to anxious behavior, and then transplanted these microbes into another strain inclined to be calm. The result: The tranquil animals appeared to become anxious.
Anxiety-like behavior in mice is one thing, but research involving humans has also proved promising. In early 2015, a paper published in Psychopharmacology discussed research on prebiotics and how they affect our positive and negative word associations.
In this experiment, subjects who ingested GOS showed lower levels of a key stress hormone, cortisol, and in a test involving a series of words flashed quickly on a screen, the GOS group also focused more on positive information and less on negative. This test is often used to measure levels of anxiety and depression, since in these conditions anxious and depressed patients often focus inordinately on the threatening or negative stimuli. Burnet and his colleagues note that the results are similar to those seen when subjects take anti-depressants or anti-anxiety medications.
We can expect to hear a lot more from this avenue of research as it enters the realm of alternative therapies. Later this week, Toronto microbiologist Jason Tetro will release his new book, The Germ Files: The Surprising Ways Microbes Can Improve Your Health and Life (And How to Protect Yourself from the Bad Ones). It follows on the heels of last year’s Brain Maker in the new frontier of experimenting on our mental health through the contents of our guts.