Hypertension, also known as high blood pressure, affects hundreds of millions of persons worldwide. In the United States alone, more than 65 million individuals have hypertension. High blood pressure, if left untreated, can cause severe damage to the body's organs, including the brain, heart, blood vessels, and kidneys. Having high blood pressure may not cause symptoms until organs have been damaged. For this reason, hypertension is often called the "silent killer." The May 26, 2010, issue of JAMA contains an article about hypertension and its treatment in the United States during a recent 20-year period.