One of the key arguments forwarded by proponents of marijuana (and, particularly, its legalization) has been the claim that pot is, on the whole, not harmful …to self or society. As we noted on this blog earlier in the year, data used to support that claim – and the opposing assertion that pot is dangerous – can sometimes be hard to make sense of. Numbers used by both defenders and opponents of legalization often seem to be put in a context that serves their own particular agenda or purpose. And strong long-term numbers have up to this point been largely unavailable. That may have now changed, with the release of a new longitudinal study showing that marijuana users are far more likely than non-users to abuse alcohol or become addicted. The study also reveals that marijuana use greatly diminishes recovery rates for those already struggling with alcoholism.
The recent study, conducted by researchers from Columbia University’s Mailman School of Public Health and the City University of New York, was published in the journal Drug and Alcohol Dependence and tracked the drinking and cannabis use behaviors of 27,461 adults who enrolled in the National Epidemiologic Survey on Alcohol and Related Conditions. It found that adults who used marijuana were, over time, five times more likely to develop an alcohol use disorder (AUD) compared to adults who did not use marijuana. The researchers also found that adults who smoked marijuana when they already had an alcohol use disorder could overwhelmingly expect the problem to continue.
When study participants who were cannabis users first began smoking marijuana, none of them had an alcohol problem — defined in the study as receiving a diagnosis of either alcohol abuse or alcohol dependence. The participants were then assessed at two different time points in the future. Adults who had used marijuana at the first assessment and then again over the following three years (23 percent of the participants) were five times more likely to develop an alcohol use problem, compared to the adults who hadn’t used marijuana at either juncture (5 percent).
In addition, problem drinkers who used marijuana were far less likely to be in recovery for alcohol abuse three years later than their peers who hadn’t smoked pot.
Importantly, the study did not reveal a cause-effect relationship between cannabis use and alcohol problems. It did, however, show a strong correlation between the two that researchers believe is significant.
“Many people focus on possible negative effects of cannabis use itself, in terms of developing a cannabis use problem or the impact of cannabis use on brain function,” said study lead researcher Renee Goodwin, adjunct associate professor of epidemiology at Columbia University’s Mailman School of Public Health in New York City. “Our results suggest that even in the absence of a cannabis use problem, using marijuana appears to increase vulnerability to developing an alcohol use problem.”
Goodwin’s research does seem to illustrate a pattern that is far more than coincidental. In fact, her findings of a correlation between marijuana use and alcohol abuse is supported by a separate study published in the journal JAMA Psychiatry in April. That study found that adult marijuana use was associated with a greater likelihood of developing alcohol and drug problems, including nicotine dependence. It examined nearly 35,000 adults interviewed over the course of three years as part of the National Epidemiologic Survey on Alcohol and Related Conditions. Almost 1,300 of those subjects used marijuana. At the three-year follow-up, the cannabis users in the study were found to be about six times more likely to have any substance abuse disorder, nearly three times as likely to have an alcohol disorder, and about 10 times as likely to report any marijuana use disorder. Cannabis users were also nearly twice as likely to report nicotine dependence.
Lead researcher Dr. Mark Olfson, a professor of psychiatry at Columbia University Medical Center, suggests that his study “raises the possibility that the recent rise in marijuana use may be contributing to the coincident rise in serious harms related to narcotics and other drugs of abuse.”
Olfson was also careful to stress that his research could not firmly establish a causal relationship between smoking marijuana and drinking or other drug use. But he does believe that drug policies and approaches to addiction and treatment should reflect a respect for these new, long-term scientific studies.
“In the ongoing national debate concerning whether to legalize recreational marijuana, the public and legislators should take into consideration the potential for marijuana use to increase the risk of developing alcohol abuse and other serious drug problems.”
Whether or not this latest round of research will change hearts and minds – particularly of those who see marijuana as a medically useful substance and who believe that it is not (in and of itself) too damaging – remains to be seen. But, armed with new data, the suggestion that marijuana cannot be a gateway to other damaging drugs does seem go “up in smoke.” At least from our perspective…