Patients with post-traumatic stress disorder (PTSD) show differences in gut bacteria compared to other trauma-exposed people who never went on to develop PTSD, according to a new study led by researchers at Stellenbosch University in South Africa.
In recent years, research has shown just how vital the gut microbiome is to human health. These microbes perform important functions, such as metabolizing food and medicine and fighting infections. It has also been shown that gut microbes influence the brain and brain function by producing neurotransmitters/hormones, immune-regulating molecules, and bacterial toxins.
However, stress hormones can have a negative impact on gut bacteria and compromise the integrity of the intestinal lining, allowing bacteria and toxins to enter the bloodstream. This can lead to inflammation, which has been shown to play a role in several types of psychiatric disorders.
“Our study compared the gut microbiomes of individuals with PTSD to that of people who also experienced significant trauma, but did not develop PTSD (trauma-exposed controls). We identified a combination of three bacteria (actinobacteria, lentisphaerae, and verrucomicrobia) that were different in people with PTSD,” said lead researcher Dr. Stefanie Malan-Muller from the Faculty of Medicine and Health Sciences.
The findings show that people with PTSD had significantly lower levels of these three types of bacteria compared to trauma-exposed control groups. Individuals who experienced trauma during their childhood also had lower levels of two of these bacteria: actinobacteria and verrucomicrobia.
“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,” said Malan-Muller.
One of the known functions of these bacteria is immune system regulation, and scientists have found increased levels of inflammation and altered immune regulation in patients with PTSD.
“Changes in immune regulation and increased inflammation also impact the brain, brain functioning, and behaviour. Levels of inflammatory markers measured in individuals shortly after a traumatic event, was shown to predict later development of PTSD,” said Malan-Muller.
“We therefore hypothesize that the low levels of those three bacteria may have resulted in immune dysregulation and heightened levels of inflammation in individuals with PTSD, which may have contributed to their disease symptoms.”
However, researchers are unable to determine whether this bacterial deficit contributed to PTSD susceptibility, or whether it occurred as a consequence of PTSD.
“It does, however, bring us one step closer to understanding the factors that might play a role in PTSD,” Malan-Muller said.
“Factors influencing susceptibility and resilience to developing PTSD are not yet fully understood, and identifying and understanding all these contributing factors could in future contribute to better treatments, 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.”
Source: Stellenbosch University