Gout is a common form of inflammatory arthritis that afflicts about 8.5 million people in the United States with sudden, severe pain in knee and toe joints. Its nickname, the disease of kings, stems from an old belief that only those who could afford a rich diet would contract gout, but now it’s on the rise among the masses, too. But new research has found a positive aspect to gout: It may help protect against Alzheimer’s disease. Hyon Choi, professor of medicine at Massachusetts General Hospital, is the leader of the new research.