Johannesburg: Gut bacteria may help predict the risk of developing post traumatic stress disorder (PTSD) after experiencing a life-threatening trauma, a study has found.
PTSD is a serious psychiatric disorder that can develop after a person experiences a traumatic event.
However, not everyone exposed to a traumatic event will develop PTSD, and several factors influence an individual's susceptibility, including living conditions, childhood experiences and genetic makeup.
In recent years, scientists have become aware of the important role of microbes existing inside the human gastrointestinal tract, called the gut microbiome.
These microbes perform important functions, such as metabolising food and medicine, and fighting infections.
It is now believed that the gut microbiome also influences the brain and brain function by producing neurotransmitters/hormones, immune-regulating molecules and bacterial toxins.
"Our study compared the gut microbiomes of individuals with PTSD to that of people who also experienced significant trauma, but did not develop PTSD," said Stefanie Malan-Muller, postdoctoral fellow at Stellenbosch University in South Africa.
"We identified a combination of three bacteria (Actinobacteria, Lentisphaerae and Verrucomicrobia) that were different in people with PTSD," said Malan-Muller, who collaborated with researchers from the University of Colorado Boulder in the US for the study.
Individuals with PTSD had significantly lower levels of this trio of bacteria compared to trauma-exposed control groups, researchers said.
Those who experienced trauma during their childhood also had lower levels of two of the bacteria - Actinobacteria and Verrucomicrobia, they said.
"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.
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," she 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, researchers said.
