Alzheimer’s disease, long seen as a disorder of the aging brain, may actually begin in an unexpected place: the mouth.Researchers reported evidence that a bacterium commonly associated with chronic gum disease could play a direct role in the development of Alzheimer’s. The study, published in Science Advances, details how Porphyromonas gingivalis, the pathogen behind periodontitis, was detected in the brains of Alzheimer’s patients. The findings come from an international team of scientists that included Jan Potempa, a microbiologist at the University of Louisville. Potempa said the research offers some of the strongest evidence yet linking gum infection to Alzheimer’s pathology,...