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Cannabis dependence and withdrawal.

Subject(s): CANNABIS -- Europe; DRUGS -- Europe
Source: Addiction, Sep99, Vol. 94 Issue 9, p1277, 1p
Author(s): Farrell, Michael
Abstract: Editorial. Focuses on the drug, cannabis. Scale usage and normalization of consumption at some populations in Europe; Growth in the size of the using population; Inability to cut down or stop cannabis use; Nature of dependence.
AN: 2301745
ISSN: 0965-2140
Database: Academic Search Elite

Section: EDITORIAL
CANNABIS DEPENDENCE AND WITHDRAWAL

As we reach into at least the third decade of prevalent cannabis use of the modern era, is it just possible that we are beginning to observe the maturation of discussion on some cannabis-related issues?

Cannabis remains a hot policy topic with strong degrees of polarization of views on the risks and benefits of cannabis. Cannabis is now by far the most commonly consumed illicit drug, with 10-30% of the population in Europe reporting ever use and significant reports of chronic usage in some countries.

This scale of usage and the gradual normalization of consumption in some populations allows for greater possibilities for more accurate epidemiological studies based partially on a readiness to self-report honestly on cannabis use and also because the greater prevalence of use allows for easier access to populations to study.

The growth in the size of the using population and in particular the availability of populations of chronic heavy users now opens thedoors for more precise studies of the long-term impact of heavy usage. There are now some studies of the characteristics of long-term users (Swift et al., 1998) and there appears to be a growing number of studies of strategies for assisting in the cessation of cannabis use.

Inability to cut down or stop cannabis use is a real phenomenon which has received surprisingly limited attention until recently. This is presumably linked to the debate on whether or not cannabis is addictive. This is a somewhat curious debate, given the animal literature on the subject. Tolerance to cannabis, withdrawal from cannabis and dependence on cannabis is demonstrated clearly in animals (Pertwe, 1991). Recent antagonist studies further confirm these withdrawal phenomena (Aceto et al., 1996). Withdrawal phenomena in humans have also been reported with much of the work being done in the 1970s. Jones (1983) has reviewed this topic comprehensively and reports that the signs of cannabis withdrawal have been relatively mild and are comparable to the symptoms of withdrawal from short, low-dose treatment with opioids or ethanol. These symptoms may be dose-related. Irritability and increased aggression may be associated with withdrawal in chronic cannabis users. Budney et al., in this issue, report on a small sample of treatment seekers who were experiencing withdrawal symptoms. However, there are always problems differentiating withdrawal symptoms from other mood and anxiety symptoms in a population presenting to a treatment service. Swift et al. (1998) have reported on dependence in cohorts of long-term cannabis users. They reported limited withdrawal phenomena but argued that this may be related to the sample's ready access to cannabis on a continuous basis. Large-scale population studies report significant rates of cannabis dependence (Kessler et al., 1994; Farrell et al., 1998), particularly in prison and homeless populations.

Does this now mean that there is no controversy around the dependence liability of cannabis? Well, not exactly. We can now agree that many people meet internationally agreed criteria for dependence but we are still not sure what it means and what significance it has for the individual, for the clinician or on a public health level.

Dependence and the nature of dependence as described originally was a dimensional description of a provisional nature (Edwards & Gross, 1976). Overall there is a need for careful exploration of the meaning and nature of cannabis dependence and its overall clinical utility and public health significance. Such work is likely to be richly productive in an era with a growing population of heavy cannabis users, some of whom seek help to stop their smoking habit. Cannabis as a habit is here to stay.

References

BUDNEY, A., Novy, P. & HUGHES, J. (1999) Marijuana withdrawal among adults seeking treatment for marijuana dependence, Addiction, 94, 1311-1321.

EDWARDS, G. & GROSS, M. M. (1976) Alcohol dependence: provisional description of a clinical syndrome, British Medical Journal, 1, 1058-1061.

FARRELL, M., HOWLS, S., TAYLOR, C. et al. (1998) Substance misuse and psychiatric comorbidity: an overview of the OPCS national psychiatric morbidity survey, Addictive Behaviour, 23, 909-918.

JONES, g. T. (1983) Cannabis withdrawal, in: FEHR, K. & KALANT, H. (Eds) Cannabis and Health Hazards, pp. 617-689 (Toronto, Addiction Research Foundation).

KESSLER, R., MCGONAGLE, K., ZHAO, S. et al. (1994) Lifetime and 12 month prevalence of DSM-III-R psychiatric disorders in the United States: results from the National Comorbidity Survey, Archives of General Psychiatry, 51, 8-19.

PERTWEE, R. (1991) Tolerance and dependence on psychotropic cannabinoids, in: PRATT, J. A. (Ed.) The Biological Basis of Drug Tolerance and Dependence, pp. 232-263 (San Diego, CA, Academic Press).

SWIFT, W., HALL, W., DIDCOTT, P. & REILLY, D. (1998) Patterns and correlates of cannabis dependence among long term users in an Australian rural area, Addiction, 93, 1149-1160.

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By S-Michael Farrell, Senior Lecturer and Consultant Psychiatrist, National Addiction Centre, 4 Windsor Walk, London SE5 8AF, UK