Illicit drug use by seniors is on the rise. That could lead to a significant increase in the need for drug treatment services for seniors over the next decade, according to a new report.

The baby boom generation has a high rate of lifetime drug use, according to the report from the Substance Abuse and Mental Health Services Administration (SAMHSA). As that population ages, the number of adults using illicit drugs is also likely to rise, SAMHSA predicts. While the current generation of senior citizens is more likely to use prescription drugs for non-medical purposes, the upcoming generation of seniors is more likely to use drugs like marijuana instead, according to the survey. Last year, roughly 4.7% of adults—roughly 4.3 million people—aged 50 and older used an illicit drug. Among those aged 50 to 54, 8.5% of men and 3.9% of women used marijuana.

Over the next 10 years, the need for drug abuse treatment services for seniors is likely to double, the SAMHSA report concludes. The full report is available online for free at the SAMHSA Web site.