May 17/Hamilton, Ont./McMaster Daily News -- For the first time, researchers at McMaster University have conclusive evidence that bacteria residing in the gut influence brain chemistry and behavior. The findings are important because several common types of gastrointestinal disease, including irritable bowel syndrome, are frequently associated with anxiety or depression. In addition, there has been speculation that some psychiatric disorders, such as late onset autism, may be associated with an abnormal bacterial content in the gut.

"The exciting results provide stimulus for further investigating a microbial component to the causation of behavioral illnesses," said Stephen Collins, professor of medicine and associate dean of research, Michael G. DeGroote School of Medicine. Collins and Premysl Bercik, assistant professor of medicine, undertook the research in the Farncombe Family Digestive Health Research Institute.