Early evidence for “mood microbes”

Available for over a year

One of the key studies that ignited the whole field took place in Japan in 2004. The team at Kyushu University bred both normal mice and those completely free of microbes. The researchers then put the animals in highly stressful situations. Those without microbes pumped out twice the amount of stress hormone. It was an inspiration for Jane Foster, a neuropsychiatrist at McMaster University in Canada.