The research was carried out by the RAND Drug Policy Research Center and the University of California, Irvine. They looked at cannabis use patterns among participants between 18 and 90 years of age in four states. Colorado, Washington, New Mexico, and Oregon were chosen since they all legalized medical marijuana, with New Mexico being the only one that doesn’t allow recreational use which the other three do allow.
The authors of the study noted that “Individuals who use cannabis do not commonly use it with alcohol, irrespective of whether they are consuming cannabis recreationally or medically. Fewer than one in five recreational users report simultaneous use of alcohol and cannabis most or all of the time and less than three percent of medicinal users report frequent simultaneous use of alcohol and cannabis.”
This also helps support the trend of people giving up the pharmaceuticals and replacing them with medical cannabis.
The studies are conflicting since they don’t all reach this same conclusion, but there will certainly need to be more work done in the future in this area. Since legalization is slowly happening in one form or another throughout North America, expect to see more scientific work done on subjects like this.