Over time, some conditions and diseases may begin to affect different age groups, and the reasons why are not always clear. Sometimes it may be due to more awareness or better diagnostic tests while other times it may be caused by changes in behaviors or the environment. Six conditions are trending younger than in the past: sexually transmitted diseases (STDs), obesity, type 2 diabetes, eating disorders, high blood pressure, and colon cancer. To learn more, click "View Slideshow."