Monday, February 1, 2016

A Roundtable Discussion on Cannabis Use Disorder

Addressing the habit-forming aspects of marijuana.

A trio of leading marijuana scientists participated in a panel discussion moderated by Dr. Daniele Piomelli from the School of Medicine at the University of California-Irvine, and published in a recent issue of the journal Cannabis and Cannabinoid Research.

Dr. Margaret Haney is with the New York State Psychiatric Institute at Columbia University Medical Center; Dr. Alan J. Budney is affiliated with the Geisel School of Medicine at Dartmouth College; and Dr. Pier Vincenzo Piazza works at the Magendie Neurocenter in Bordeaux, France.

Excerpts from the long discussion appear below:

It seems that most specialists in the field agree that Cannabis is addictive. If you had to choose one piece of evidence, either clinical evidence or animal experiment evidence, in support of this conclusion, which one would you pick?

Dr. Margaret Haney: “One of the key features for me is demonstrating that there is a pharmacologically specific withdrawal from Cannabis use…. We can demonstrate that daily smokers go through a time-dependent and pharmacologically specific withdrawal when they abstain from Cannabis…. I think another really important feature is the clinical data showing how high relapse rates are with Cannabis. Although Cannabis may have a lower abuse liability than other drugs like cocaine or nicotine, once somebody has developed a dependence on the drug, then quitting becomes extremely difficult.

Dr. Alan J. Budney: “If I had to pick out the ‘smoking gun’ to convince the public and the scientific world that Cannabis Use Disorder (CUD) is real, then it would be the data from clinical epidemiological research…. the data on CUDs are remarkably similar to the other substance use disorders…. for a substantial number of people, Cannabis use causes similar and substantial problems that are comparable to other types of drugs that we all agree have addictive potential.”

Dr. Pier Vincenzo Piazza: “[In] Australia, Canada, the United States, and the European Union, over the last two years Cannabis represents the highest new entries for treatment in specialized centers…. Since these four countries have very different rates of referral of patients by the judicial system, these figures really mean that patients experience a discomfort high enough to spontaneously seek treatment…. In France, for example, as well as in many other European countries, referral from the judicial system is very low. Nevertheless, the demand for treatment for CUD is now the highest of all drugs, legal and illegal.”

What is curious is that we now accept the concept that Cannabis is addictive, but for many years we have been told that it was not. Why is it that, for so long, the scientific community failed to recognize the addictive properties of Cannabis?

Dr. Margaret Haney: “I have been speaking about Cannabis addiction for 20 years and was met by full-on boredom for the first 15 years because I felt that scientists, like the public at large, just viewed Cannabis as a benign compound not too different from caffeine in a way…. THC is lipophilic, and so long-lasting, withdrawal takes quite a while to manifest…. if an individual is dependent on nicotine, he or she cannot go a couple of hours without experiencing withdrawal. A heavy Cannabis user, by contrast, has to go quite a while before experiencing withdrawal, and so it was not quite as obvious to people that withdrawal existed.”

Dr. Alan J. Budney: “Moreover, many of those that have experience with using Cannabis, do not get addicted, develop problems, or experience withdrawal. Although the same is true for those who have used alcohol or even opiates, for reasons that are not completely clear, the personal experience of those who used Cannabis and did not develop problems or experience withdrawal, seems to lead to the perception that Cannabis is not a substance that others can become addicted to.”

Dr. Pier Vincenzo Piazza: “What we know now is that, since cannabidiol is an antagonist of THC, the greater the ratio between THC and cannabidiol the greater the risk for Cannabis to be addictive…. Now, we are up to a 5- to 10-fold difference in favor of THC, making Cannabis more addictive.”

How addictive is Cannabis? Is it more addictive than, say, tobacco or alcohol? Is it less addictive? Is this question even correctly asked? Is there a better way to ask it?

Dr. Alan J. Budney: [I] would like to emphasize a point so that our audience does not think we are going way overboard and engaging in reefer madness related to the severity of Cannabis addiction. All factors held constant, the pharmacology of opiates would probably produce a more severe addiction…. Access, dose, route of administration, societal acceptance, perceived risk, cost, societal consequences for use or intoxication, and multiple other factors contribute to the real-world question of how addictive a drug is compared to another.”

Dr. Margaret Haney: “My opinion is that Cannabis has a lower abuse liability than something like cocaine [but] even if Cannabis has a lower abuse liability, the sheer number of people using it will result in a large number of people with a use disorder….”

Dr. Pier Vincenzo Piazza: “If we try to express abuse liability in numbers, the abuse liability for Cannabis… is between 10% and 15%, depending on the survey you look at. However, I believe that abuse liability should also be measured by a second factor; that is, how easy it is to quit if you have developed a substance use disorder. My understanding… is that stopping Cannabis use, if you have developed CUD, is not easier than other drugs.”

The major point, all three experts agree, is that marijuana cannot be considered a completely benign drug. “Cannabis is not the worst drug,” says Dr. Haney, “but it is not a drug without consequences. Again, societal attitudes often seem to skew one way or the other; it is all good or it is all bad, when it is clearly both.”

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