(AP) — U.S. health officials say middle-aged women are the fastest-growing group of people dying from drug overdoses.

For many decades, the overwhelming majority of U.S. overdose deaths were men killed by heroin or cocaine. But by 2010, 40 percent were women — most of them middle-aged women who took prescription painkillers.

Skyrocketing overdose death rates among females are closely tied to a boom in use of prescribed painkillers. The new report is the government’s first to spotlight how the death trend has been more dramatic among women.

The Centers for Disease Control and Prevention found that the number and rate of female prescription drug overdose deaths increased by around 400 percent from 1999 to 2010. For men, the increases were around 250 percent.