The Treatment For PTSD Could Actually Have To Do With The Bacteria In Your Gut

by JR Thorpe

If you've been paying attention to the scientific world over the past few years, you know that a particular area of the body is getting a lot of attention: the gut. This might seem surprising, but more and more evidence is revealing that our digestive system isn't just for breaking up food, giving us nutrients and getting rid of the waste. Instead, scientists have revealed the existence of something called the "gut-brain matrix," in which the digestive system reacts and interacts with different aspects of brain function, including depression and mood. And it's becoming clear that when it comes to post-traumatic stress disorder, the gut may prove to be both a source of information and a potential treatment source for people with the illness. A new research collaboration between Canadian and South African scientists, published in Psychosomatic Medicine this month, studied 30 people and found that when it comes to trauma, some specific varieties of gut bacteria might have an important role in PTSD diagnosis.

Understanding the gut is the first step to getting a handle on this peculiar situation. The real things of interest aren't your stomach and intestine themselves, but what they house: what Dr. John F. Cryan, in an article on the mind-gut axis in 2016, described as "a diverse array of trillions of microbes (mainly bacteria but also archaea, viruses, and protozoa), which is 1.3 to 10 times the number of human cells." He notes that this gut microbiome, as it's called, has been shown to influence many of the ways in which the human body works. The microbiota of the gut and the brain seem to interact in complex ways; evidence from a study in August 2017 suggests that peptides, chains of amino acids, play a role as "messengers" between the neural and endocrine systems, linking up the gut and the brain in ways we hadn't previously imagined.

The way to a man's heart may not be through his stomach, but a way to influence his brain may indeed be through his gut. And this becomes very important when it comes to traumatic experiences. We know that there's a strong link between PTSD and irritable bowel syndrome, and there's a lot of evidence that suggests that PTSD's relationship to gut microbiota generally sheds an unexpected light on trauma and how it manifests in the body.

The Relationship Between Trauma & The Gut Is Complex

One of the most enduring questions in PTSD studies is: why do some people develop it after trauma when others don't? It's a peculiar question and there are many possible answers. The new study from Psychosomatic Medicine set out to investigate why only 3.5 percent of the people who experience severe trauma develop PTSD. To find out if gut microbiota might have something to do with it, they studied the gut flora of 18 people with PTSD and 12 people who'd had traumatic experiences but hadn't developed the disorder. And what they found raises a lot of intriguing questions.

The people who had PTSD had significantly lower levels of three bacteria (Actinobacteria, Verrucomicrobia and Lentisphaerae) than the whole trauma-exposed group, while those people who'd had trauma in their childhoods but hadn't developed PTSD had lower levels of the first two, according to the study. But the results aren't as simple as it seems on the surface. One of the lead scientists, Dr. Stephanie Malan-Muller, pointed out in an essay on The Conversation that these low levels of bacteria "may have contributed to a deficient immune system and heightened inflammation, which may have contributed to symptoms of PTSD. It is, however, still unclear when these changes in the microbiome might have taken place. They may have occurred early in life as a response to childhood trauma." And, she added, "we can’t say whether the disorder causes the bacterial deficit or if the bacterial deficit contributes to PTSD symptoms." It's a chicken-and-egg problem: which came first, the deficient microbiota or the PTSD? And which caused the other?

The relationship between microbiota and stress in childhood has actually been discussed before. Research published in 2016 suggested that people might be more susceptible to PTSD if they'd already been exposed to trauma in early life, which changed their gut microbe balance in a way that influenced their nervous and immune systems as they grew older. Dr. Cryan, commenting on this idea, mentions that the gut microbiome might also interact with the amygdala, an area of the brain that becomes hyperactive in PTSD patients and controls fear responses. Fiddling with bacteria in the gut has been shown to alter fear learning in the brain, so it's plausible that people with PTSD are suffering worsened symptoms because their gut biome has retrained their brains. Sounds like science fiction, but sometimes real science is weirder than you could ever imagine.

Can You Treat PTSD With Gut Bacteria?

Even more intriguing than the potential causal link between the two, is the possibility that the gut biome could be used to treat people with PTSD. The scientists behind the 2016 study on gut microbiota and early life think it could. "It may be possible to target abnormalities in [nervous and immune systems] by manipulation of certain gut bacterial communities directly through supplementation or indirectly by dietary and other novel approaches," they wrote.

This idea is currently being tested among American veterans. Following a promising study in mice, Veteran Affairs is doing a study on 40 veterans, all with diagnosed PTSD and mild concussion using a substance called Lactobacillus reuteri, isolated from human breast milk. Subjects take a small amount of the stuff every night. They are having their stools tested and their biomarkers closely monitored, and their levels of inflammation recorded (PTSD is related to excessive inflammation, and the bacteria of the gut might be to blame) to see if the Lactobacillus, which is sold over the counter to soothe colicky babies, might reduce anxiety symptoms in PTSD sufferers. It's an interesting but very small study using only one bacterium we know to be safe for human consumption, so it's just the beginning of investigation. One day, it's not outside the realms of imagination to hope that the digestive-health aisle at the drug store might have doses on hand to balance gut microbiota in people with mood disorders and anxiety. The link between trauma and the microbiome of the gut is an interesting one, and future science will help us understand the many ways in which the psychological and the physical interact in our bodies.