Cannabis, dependence potential

In an interview study (Robson and Bruce 1997), the dependence potential of various street drugs was assessed in 201 problem and 380 social users of heroin, cocaine or amphetamine using the well-validated Severity of Dependence Scale (SDS). Scores (maximum = 15) in the problem group were 12.9 for heroin, 9.6 for other opioids, 6.1 for amphetamine and 5.5 for crack cocaine. All of these scores were consistent with findings in other studies. Cannabis SDS score was 2.6 and comparable with those of LSD (3.1) and ecstasy (1.3), two drugs that are generally not associated with physical or psychological dependence. In the parallel sample of social users, the cannabis SDS was similar at 3.4. 

Cannabis carries some potential for dependence and addiction. Compared to cocaine, heroin, alcohol, and nicotine, cannabis has lesser addictive potential and withdrawal effects, but some users do develop compulsive and maladaptive use patterns that require treatment (Taylor 1998). Individuals with underlying psychopathology or tendencies for substance abuse should be particularly leery of using cannabis in the interests of avoiding compulsive use patterns. 

Properties of THC that may have a bearing on its dependency and abuse potential have been investigated in numerous animal models, but how reliable these may be in predicting human behaviour is open to question. Despite the cripplingly expensive War on Drugs, recreational cannabis is still easily available, cheaper in real terms and used extensively throughout the world, so it seems sensible to examine what actually happens outside the laboratory. 

There are two primary sources for the information in this section. In 1998, ONDCP supported a study by the National Academy of Sciences Institute of Medicine (lOM) on marijuana s potential benefits and harms. In one of the quotes from Drug Czar John Walters in an earlier section of this chapter, he refers to a result from this study. The lOM report is one source for the information reviewed here. The second source is a book titled Cannabis Use and Dependence Public Health and Public Policy (Cannabis Book). The authors are from the University of Queensland (Australia) and the RAND Corporation s Drug Policy Research Center, a well-respected organization that receives a lot of federal grant money in the substance abuse area. The Cannabis Book contains an impressive review of literature on all aspects of marij uana use, effects, and policy. In a review appearing in aprofessional journal, this book was described as ... the most comprehensive and honest attempt to improve the quality of the public policy debate on cannabis. " While it is probably not possible for any source to be completely objective, these documents seem to be very balanced and no discemable bias could be detected. 

However, the problem with hashish and marijuana as a medication is their route of apphcation and their standardisation. Resorption kinetics and bioavail-abftity are highly dependent on the administration form. In addition, the content of active ingredients in cannabis fluctuates considerably, what makes it hard to compare data from different chnical studies, apart from any potential planning errors that may also have occiured. Microbial pollutants, which lead to allergies and breathing illnesses, pose another problem. AH this favours the chemical total synthesis of the pure active material. Thereby, a targeted co-administration of several cannabinoids may become feasible in the future. 

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