Stress brought about by experiences in one's early life may lead to the growth of bacteria in the gut and this bacteria has been linked to depression and anxiety by scientists in a new study.
While it has been proven in previous researches that gut bacteria can affect behavior, scientists from the Farncombe Family Digestive Health Research Institute at McMaster University in Canada did this new experiment to show its effects using two groups of mice. One set, the control group, had gut bacteria present in their system, while the other group had no presence of the bacteria at all.
The mice were then subjected to early-life stress, separating them from their mothers for three to 21 days.
The result showed that the control group developed stress hormones called corticosterone at alarming levels and they also exhibited anxiety and depression-like behaviors. These mice also had impaired intestinal function.
The group of mice with no gut bacteria, meanwhile, also showed the same corticosterone increase and intestine impairment, but the depressive-like behavior was interestingly absent.
The researchers then colonized the second group with bacteria from the controlled group and saw that anxiety and depressive behavior manifested in its subjects after a few weeks. But colonizing the control group with bacteria from the second group showed no abnormalities.
"This suggests that in this model, both host and microbial factors are required for the development of anxiety and depression-like behavior. Neonatal stress leads to increased stress reactivity and gut dysfunction that changes the gut microbiota which, in turn, alters brain function," said Premysl Bercik, one of the study's authors, according to Science Daily.
Researchers are only starting to learn the complexities of gut bacteria in relation to a person's mental health. But with this study, they concluded that "relatively minor changes in microbiota profiles or its metabolic activity induced by neonatal stress can have profound effects on host behavior in adulthood."
The study hopes that this will help other researches on psychiatric disorders and practices in the medical field, particularly in fecal transplants, according to ABC.
"We should maybe think: 'Is this human donor really healthy from the mental point of view? Does he or she have any history of depression or anxiety?" Bercick said. "Because there is a chance that we might be also transferring some susceptibility or possibility of developing these kinds of disorders to the recipient."
The findings were published in the journal Nature Communcations.
