Substance use disorders, suicides and diabetes are driving a rise in premature deaths in almost half of the United States, according to a new study published in the Journal of the American Medical Association.

The study analyzed variations in death rates among people ages 20 to 55, The Wall Street Journal reports. The study found the risk of dying at an early age declined in Minnesota, California and New York between 1990 and 2016, while it rose in 21 states, including West Virginia and New Mexico.

In West Virginia, one of the states hardest hit by the opioid epidemic, mental and substance use disorders were the biggest driver of an increase in the probability of death among young and middle-aged adults. In Oklahoma, those factors, along with cirrhosis, were major contributors to an increase in the risk of death among this age group.