Posttraumatic stress disorder (PTSD) may be caused by deteriorated intestinal microbiota
Inflammation caused by the deterioration of the bacterial balance in intestines may worsen PTSD
Many clinical studies reveal that patients with depression, a type of psychiatric disorder, show an increasing number of inflammatory substances in their blood. Furthermore, a study using mice has unveiled that when inflammation is induced in intestines by lipopolysaccharide (LPS) which is a component derived from bad bacteria, the level of stress tolerance of mice after they get stressed was lowered which in turn causes symptoms that resemble that of depression. Based on these results, we can make a prediction that when the intestinal bacterial balance is deteriorated, the permeability of intestinal epithelial cells increases and components such as LPS enter the bloodstream, which in turn decreases the level of stress tolerance. Researchers also pointed out the relationship between the intestinal inflammation and disorders of the secretion of neurotransmitters such as dopamine, serotonin, and GABA.
What we now know from these accumulated data is that the increased inflammatory substances in the blood can be related to the development of PTSD after experiencing traumatic events. Also, patients with PTSD have a low level of cortisol known as an anti-stress hormone. There are also expectations that the state of inflammation and the low level of cortisol might have been caused by the intestinal conditions of those people in their childhood.
People with trauma tend to have less amount in certain intestinal bacteria
The research published by the University of South Africa in 2017 analyzed the DNA of bacteria collected from 18 subjects with PTSD and 12 subjects who experienced an event that can be traumatic but did not actually develop PTSD symptoms. According to the results, the amount of Actinobacteria and Verrucomicrobia tended to be less in the intestines of those who experienced a traumatic event when they were a child. However, they have not concluded in this paper whether the reduction of intestinal bacteria has caused PTSD or PTSD caused the decrease of intestinal bacteria.
However, the test using mice unveiled that the aggravated condition of intestinal bacteria of newborn mice could affect their behavior afterward, and there was a difference in a state of
anxiety and stress tolerance between germ-free mice and the other mice with bacteria in their intestines. These test results suggest that the deterioration of the bacterial condition in the intestines may be a risk factor for the onset of PTSD.
Exacerbations of gastrointestinal symptoms such as complications of severe constipation are common among patients with mental disorders such as depression. However, several studies have reported that those symptoms were improved by the ingestion of lactic acid bacteria and fermented foods. Now, it is expected that symptoms of PTSD will be improved by taking approaches to gastrointestinal symptoms.
Credit to: Muneaki Takahata Ph.,D.
- Psychosom Med. 79, 936-946 (2017)
- Can J Psychiatry. 6, 204-213 (2016)
- Business Performance Report. Subsidies for promoting comprehensive improvements in
welfare for the disabled, Ministry of Health, Labor and Welfare in 2010