Half of adults ages 20 to 39 with attention deficit hyperactivity disorder (ADHD) have had a substance use disorder, a new study finds. In contrast, 23.6% of young adults without ADHD have had a substance use disorder in their lifetime.

Young adults with ADHD and a history of depression or anxiety are especially vulnerable to developing a substance use disorder, researchers at the University of Toronto found.

“People with ADHD may be self-medicating with drugs or alcohol to keep their depression under control, and of course, that is a recipe for disaster,” lead researcher Esme Fuller-Thomson said in a news release. The findings “underline the need for effective interventions to address substance use disorders among those with ADHD,” she said.

The study found alcohol use disorders were the most common substance use disorders among young adults with ADHD (36%), followed by cannabis use disorders (23%), HealthDay reports.