Gut microbiome disruptions in infancy increase aggression later in life, including causing changes to aggression-related genes, according to a new study in mice who received a gut bacteria transplant from one-month-old human infants.

I’ve linked to the news release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:

https://www.sciencedirect.com/science/article/pii/S0889159124005336

From the linked article:

Gut bacteria that have been disrupted in infancy can lead to greater aggression later in life, including causing changes to aggression-related genes, according to a new study. The findings warrant more research into the complex interplay between the gut, brain, and aggression.

One set of five-week-old mice received a gut bacteria transplant from one-month-old human infants who’d been given antibiotics within 48 hours of birth, and therefore, the diversity of their gut bacteria was reduced; another set was transplanted with non-antibiotic-affected infant microbiota. Four weeks post-transplant, the mice that received the gut bacteria lacking diversity were found to be more aggressive than those that hadn’t.

When they examined the biochemical and neurological changes in mice that received antibiotic-altered microbiome transplants, the researchers found that those mice showed significant changes in the expression of aggression-related genes across five brain regions. In addition, the mice with depleted gut bacteria had a significant reduction in serotonin and a significant elevation in tryptophan, an amino acid that helps make serotonin.

“These findings highlight the complex interplay between the gut microbiome and aggression, providing valuable insights into the underlying biological processes involved,” said the researchers. “However, further research is needed to fully understand the multi-faceted interactions between gut microbiota, gene expression, and aggression, and how these findings can be translated into clinical applications.”