Rebalancing the bacteria in the gut with a fecal transplant leads to positive behavioral changes in children with autism. That’s the outcome of a new study. A fecal transplant is a method of introducing donated healthy microbes into people with gastrointestinal disease to rebalance the gut. The new study adds to a growing body of research that is drawing connections between the bacteria and viruses that inhabit the gut and problems in the brain. Alzheimer’s and Parkinson’s disease have also been linked to gut problems.