Newswise — There is a lack of agreement about the relationship between marijuana and alcohol use. Does marijuana use increase or decrease alcohol consumption? Research based on interviews with users of both marijuana and alcohol reveals that recreational users tend to drink more alcohol, and medicinal users drink less alcohol, on marijuana-use days. These results and others will be shared at the 42ndannual scientific meeting of the Research Society on Alcoholism (RSA) in Minneapolis June 22-26.

“There is conflicting evidence in the literature as to whether cannabis acts as a substitute, meaning that it replaces the effects of alcohol, or complement, meaning that it enhances alcohol intoxication,” said Rachel Gunn, postdoctoral research fellow at BrownUniversity. “In other words, there is evidence on both sides of the debate: that individuals both drink more and drink less when using cannabis on the same day.”

Gunnwill discuss her findings at the RSA meeting on Monday, June 24.

“We hoped to clarify this debate by examining daily patterns of alcohol and cannabis co-use in a sample of veterans who use cannabis for both medicinal and recreational reasons,” said Gunn. “We examined medicinal versus recreational users because they appear to have very different cannabis and alcohol use patterns. For instance, recreational users tend to drink more compared to medicinal users. We collected three waves of data from these two groups across a period of 540 calendar days.”

Gunn described three main findings. “One, daily use of cannabis is associated with increased drinking in the same day among recreational users,” she said. “Two, daily use of cannabis is notassociated with increased drinking in the same day among medicinal users. Three, medicinal cannabis users who report more frequently using cannabis as a replacement for alcohol drink less on days that they use cannabis compared to days they do not.”

Gunn stressed the need for interventions that recognize recreational use of marijuana is a risk factor for alcohol use and related problems. “There is also a need for additional research on the impact of differing cannabis formulations, such as cannabidiol (CBD) versus Δ9–tetrahydrocannabinol (THC), on alcohol craving and consumption,” she added. “Also, on how patterns of use may differ for individuals with a diverse set of conditions and reasons for using medicinal cannabis.”