Antibiotics that kill gut bacteria also stop growth of new brain cells -- ScienceDaily

"Antibiotics strong enough to kill off gut bacteria can also stop the growth of new brain cells in the hippocampus, a section of the brain associated with memory, reports a new study in mice. Researchers also uncovered a clue to why -- a type of white blood cell seems to act as a communicator between the brain, the immune system, and the gut."