Marijuana smokers five times more likely to turn into alcoholics

Adults who smoke marijuana -- the most commonly used psychoactive drug or medicine -- are five times more likely to develop an alcohol use disorder (AUD) -- alcohol abuse or dependence -- compared with adults who do not smoke it, warns a study.

For those people already battling an alcohol use disorder, using marijuana is likely to aggravate their dependency.

Adult drinkers who did not use marijuana were significantly more likely to be in recovery from alcohol use disorders three years later.

"Our results suggest that cannabis use appears to be associated with an increased vulnerability to developing an alcohol use disorder, even among those without any history of this," said Renee Goodwin, associate professor at the University of Columbia in New York, US.

"Marijuana use also appears to increase the likelihood that an existing alcohol use disorder will continue over time," she added.

The results, published online in the journal Drug and Alcohol Dependence, showed that adults who had used marijuana in the first assessment and again over the research following three years (23 percent) were five times more likely to develop an alcohol use problem, compared with those who had not used marijuana (five percent).

The researchers analysed 27,461 adults who first used marijuana at a time when they had no lifetime history of alcohol use disorders.