Opioid-related overdose deaths among U.S. adults 55 and older rose tenfold between 1999 and 2019, according to a new study.

Researchers at Northwestern Medicine found that much of the increase was driven by a rise in opioid overdose deaths among non-Hispanic Black males, according to U.S. News & World Report. Opioid overdose deaths increased from 518 in 1999 to 10,292 in 2019, the researchers found. By 2019, the opioid overdose death rate among Black men age 55 and older was about four times higher than the overall rate among others of the same age.

“Many of us think drug misuse is a problem of the young. However, older adults are experiencing an explosion in fatal opioid overdoses,” study co-author Maryann Mason said in a news release. Study senior author Lori Post said doctors often don’t screen for substance use issues during appointments with older patients because “it doesn’t fit the stereotype of what it means to be old.”