Admissions to drug treatment programs fell by almost one-quarter during the first year of the pandemic, according to a new study. The decline may help explain the increase in overdoses, according to researchers at the RAND Corporation.

“These declines in the number of Americans receiving treatment are especially noteworthy given evidence of increases in substance use disorder and overdose death rates during the same time period,” study author Jonathan Cantor said in a news release.

The researchers analyzed data from drug treatment centers receiving government funding between 2017 and 2019, before the pandemic, and during 2020, the year the pandemic began. Admissions were stable before 2020, HealthDay reports. They declined from 66 per 10,000 in 2019 to 50 per 10,000 in 2020 – a 24% drop. The decline was larger for men than for women.