The bacteria living in your gut could tell you whether you are at risk of developing post-traumatic stress disorder (PTSD). New research has suggested that people living with PTSD have low levels of bacteria that help with fighting infections.
Molecular biologists from Stellenbosch University analysed microbial DNA that they extracted from stool samples of people with PTSD and those who experienced trauma but haven't developed the disorder. They found that individuals with PTSD had lower levels of three specific gut bacteria.
The bacteria, called Actinobacteria, Lentisphaerae and Verrucomicrobia, support the functioning of the immune system. “We were interested in what these three bacteria mean in terms of PTSD,” says lead researcher of the South African study, Stefanie Malan-Muller. “We hypothesise that people with PTSD struggle to regulate their immune system functioning, and they often have high levels of inflammation.”
Not everyone who goes through trauma develops PTSD, however. This study found lower levels of Actinobacteria and Verrucomicrobia in people who had experienced childhood trauma. "What makes this finding interesting, is that individuals who experience childhood trauma are at higher risk of developing PTSD later in life, and these changes in the gut microbiome possibly occurred early in life in response to childhood trauma," Muller says.
The authors of the study, published in the journal Psychosomatic Medicine, weren’t able to conclude whether the depletion of bacteria was a cause or consequence of PTSD. “That’s kind of a chicken and egg question. We would need to do a longitudinal study of people before they developed the disorder to determine that,” Muller says. “It is possible that elevated inflammation at the time of trauma exposure is critical for determining PTSD outcomes.”
Animal studies have found that the composition of the gut microbiome (all of the bacteria in the gut) affects brain function, behaviour, memory and stress coping. Stress can affect bacterial growth and the intestinal lining, letting bacteria into the blood. This can cause inflammation, which has been shown to play a role in several psychiatric disorders.
Decreased levels of Actinobacteria (associated with higher inflammation) has been found in individuals with major depressive disorder. Researchers are also testing whether anti-inflammatory drugs can help treat such illnesses. A healthy gut has also been found to reduce anxiety-like behaviour in mice.
If researchers can link PTSD to inflammation in their next study there's potential for new PTSD treatments. “It does bring us one step closer to understanding the factors that might play a role in PTSD, and this could contribute to future treatments,” Muller says. “Especially since the microbiome can easily be altered with the use of prebiotics (non-digestible food substances), probiotics (live, beneficial microorganisms), and synbiotics (a combination of probiotics and prebiotics), or dietary interventions.”
Muller says we aren’t quite there yet with probiotics, but it’s a future possibility. “The probiotics on the market are usually made up of the same bacteria, just in different combinations. So, in future we could look at altering the exact composition to help people with PTSD” she says.
This article was originally published by WIRED UK
