Young people who quit using cannabis are more likely to increase their alcohol intake, according to a new study published in the Progress in Neuropsychopharmacology & Biological Psychiatry journal. 

A team of researchers from Harvard Medical School, Loyola University, and the University of Miami undertook this study to explore possible correlations between alcohol and cannabis use among young people. The researchers recruited 160 healthy cannabis users between 14 and 25 years of age, 84 percent of whom said that they had used alcohol within the past month. None of these subjects said that they wanted to seek treatment to quit pot. 

The study authors divided the subjects into two equal groups: one that was paid to abstain from cannabis for four weeks, and a control group that was allowed to continue getting high as they pleased. The subjects in the abstinence group were given regular drug tests to ensure they were staying away from weed, and all subjects were asked to self-report how much alcohol they were drinking during the study period.

The study reports that 60 percent of the subjects who stopped using cannabis increased their alcohol intake within the first week of abstinence. On average, the abstinence group consumed an average of 0.2 extra drinks per day and drank an average of 0.6 extra days per week. During the same study period, there was no significant change in the control group’s alcohol intake.

The abstinence group continued drinking more alcohol during the entire month that they quit smoking weed, but toned it down once they were allowed to get high again. At a follow-up session conducted 2 to 4 weeks after the abstinence period ended, subjects in this group reported that their alcohol intake declined back to their pre-trial rates.

The study authors also found a good deal of variation in how each individual responded to quitting pot. Although the majority of subjects drank more alcohol during abstinence, another 23 percent actually drank less alcohol during the study. These results “suggest that increased alcohol use during cannabis abstinence among youth merits further study to determine whether this behavior occurs among treatment seeking youth and its clinical significance,” the authors conclude.

The findings of this study may highlight unforeseen risks of cannabis treatment and rehab programs. Young people who are forced into these programs by law enforcement or their parents, or even those who enter these programs voluntarily, may well find themselves at greater risk of problematic alcohol use. 

Other research studies have also found links between alcohol and cannabis use, suggesting that pot could be a healthy substitute for booze. Researchers have found that alcohol sales have dropped in states with medical marijuana programs, and even that interest in alcohol has been declining in legal-weed states. And a more recent Canadian study found that nearly half of all patients who were using medical cannabis to curtail problem drinking were successfully able to cut down their alcohol intake or even quit entirely.