Intestinal bacteria could hold clues to whether or not an individual will develop post-traumatic stress disorder (PTSD) after experiencing a traumatic event finds a study. PTSD is a serious psychiatric disorder that can develop after a person experiences a life-threatening trauma. The findings showed that individuals with PTSD had significantly lower levels of a combination of three bacteria -- Actinobacteria Lentisphaerae and Verrucomicrobia -- 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. Individuals who experience childhood trauma are at higher risk of developing PTSD