It was a widely held assumption up until about three decades ago, in the 1980s, that stress increased the development of acidic liquids in the stomach and led to ulcers. While arguing that stress can contribute to and exacerbate gastric ulcer symptoms, recent research contradicts this theory and shows that the Helicobacter pylori, or H. pylori, bacterium is present in over 90% of cases. Its presence can be detected using a stool, blood, or breath test, and antibiotics work well to treat it.