More than one-fifth of people who use cannabis struggle with dependency or problematic use, according to a study published on Tuesday in The Journal of the American Medical Association Network Open.

The research found that 21 percent of people in the study had some degree of cannabis use disorder, which clinicians characterize broadly as problematic use of cannabis that leads to a variety of symptoms, such as recurrent social and occupational problems, indicating impairment and distress. In the study, 6.5 percent of users suffered moderate to severe disorder.