Adolescent health is getting worse, two Johns Hopkins researchers say. In a report in the Journal of the American Medical Association, they cite a number of studies from the past year. One shows that one in four teenagers report being assualted--three times what it was in 1991. One in ten say they have been sexually abused. The increase in violence is important, the researchers note, because of other studies that link the experience of sexual abuse to higher rates of alcohol abuse and sexual promiscuity.