Bacteria in the gut can influence brain chemistry, and behavior and drugs such as antibiotics can influence bowel functioning, researchers in Canada say.
Stephen Collins and Premysl Bercik of the Michael G. DeGroote School of Medicine at McMaster University in Hamilton, Ontario, showed that disrupting the normal bacterial content of the gut of healthy mice with antibiotics produced changes in behavior. The mice became less cautious or anxious.
This change was accompanied by an increase in brain derived neurotrophic factor, which has been linked to depression and anxiety, the researchers say.
However, when oral antibiotics were discontinued, bacteria in the gut returned to normal, the researchers say.
"This was accompanied by restoration of normal behavior and brain chemistry," Collins says in a statement.
These findings are important because several common types of gastrointestinal disease, including irritable bowel syndrome, are frequently associated with anxiety or depression.
In addition, some psychiatric disorders, such as late-onset autism, may be associated with an abnormal bacterial content in the gut, Collins says.