A study from researchers at the University of Colorado Anschutz Medical Campus reveals that nearly one in five U.S. adults have used multiple drugs in the past year, showing that substance use is fairly common and more complex than just using one drug at a time. The study was published last week in the American Journal of Public Health. The survey, which included 30,000 participants, found that adults who use prescription drugs, recreational drugs like cannabis, or illegal drugs like cocaine fit into four distinct patterns of drug use. 

https://news.cuanschutz.edu/news-stories/study-finds-one-in-five-u.s.-adults-use-multiple-drugs-revealing-new-patterns-in-substance-use