TL neuro

August 16, 2011

Rates of Cannabis Dependence

Filed under: Cannabis — mtaffe @ 8:07 pm

cross posted from the SCCAN blog:

One of the deceptively simple questions that often arises when it comes to cannabis (once one acknowledges that cannabis dependence exists) is that of the dependence rate. After all there are many perspectives, from public policy to parents to recreational users, all of which are concerned at some level with risk. What are the risks to personal and public health posed by recreational cannabis use? This would seem to be a simple question and yet it can be tricky to come up with a simple answer.

One of those risks associated with cannabis is drug dependence…but not everyone who smokes cannabis will meet criteria for dependence*. So how do we estimate how many people will become dependent?

One way to answer this is to rely upon survey data such as those generated by the National Survey on Drug Use and Health (NSDUH) supported by the Substance Abuse and Mental Health Services Administration (SAMHSA). A secondary analysis of the data from 2005 (survey methodology) were published in a book chapter by Koob, Kandel and Volkow (2008). Here, we have picked the rate of individuals who meet criteria for dependence on a range of drugs/drug classes.
From these data, the dependence rate for cannabis appears to be about 9.7% (10.3 for men, 8.7 for women). The overall rate is similar to those for stimulants and analgesics, which in this case refers to nonmedical use of the prescription drugs in those classes. The dependence rate for cannabis is also about half that for cocaine and a third of that for cigarettes.

Importantly, the rate is based on that population of individuals who have used the drug/drug class in question within the last year prior to the survey. This is important because the specific estimate of dependence rate will quite likely vary depending on what is used as the population of interest. Some might be interested in the rate given the population that has ever tried a given substance at least once in their lifetime. Others might wish to gate their estimates on more frequent use patterns. Obviously, changing the size of the underlying population is going to change the estimated rate of those who meet criteria for dependence at a given point in time.

Nevertheless, these survey data give one common point of reference to answer the question regarding the dependence risk of recreational cannabis use.
Koob, G. F., Kandel, D. and Volkow, N. D. (2008) Pathophysiology of Addiction, in Psychiatry, Third Edition (eds A. Tasman, J. Kay, J. A. Lieberman, M. B. First and M. Maj), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470515167.ch22

The figure has been graphed from data in Table22-3 which is based on a secondary analysis of data from NSDUH/SAMHSA 2005 survey.

*We will take up the issue of dependence on cannabis and the diagnosis thereof in subsequent posts.


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