CANNABIS: a health perspective and research agenda

World Health Organization (WHO)

May, 1995

5.5.2 Cannabis dependence syndrome

Clinical and epidemiological research has clarified the status of the cannabis dependence syndrome. A reduced emphasis on the importance formerly attached to tolerance and withdrawal symptoms in diagnostic criteria for dependence has removed a major reason for scepticism about the existence of a cannabis dependence syndrome. Clinical and epidemiological research using standardised diagnostic criteria has produced good evidence for a cannabis dependence syndrome that is characterized by impairment, or loss of control over use of the substance, cognitive and motivational handicaps which interfere with occupational performance and are due to cannabis use, and other related problems such as lowered self-esteem and depression particularly in long-term heavy users (Anthony & Helzer, 1991). As with other psychoactive substances, the risk of developing dependence is highest among those with a history of daily cannabis use. It is estimated that about half of those who use cannabis daily will become dependent (Anthony & Helzer, 1991). Cannabis dependence treatment programmes

are not widespread and the outcome of the treatment often relies on the substance user having a greater sense of economic security and a lower inclination to drop out of the programme, with those staying in the programme having the greatest success rates of quitting cannabis smoking (Stephens et al., 1993; Roffman et al., 1993). The large discrepancy between population prevalence estimates and the small numbers of cannabis users seeking treatment suggests that there is a high rate of remission in the absence of treatment, while a lack of motivation to seek treatment and to stop use cannot be ruled out.

Since tolerance and withdrawal symptoms are still widely regarded as diagnostic criteria of substance dependence, it is worth noting that there is abundant experimental evidence of tolerance to many of the effects of cannabis. There is not yet universal agreement about the production of a withdrawal syndrome. Although a recent study has demonstrated that long term administration of cannabinoid to rats alters the central nervous system in a manner similar to that observed with other drugs of abuse and also, induces neuroadaptive processes which correspond to a cannabis withdrawal syndrome (de Fonseca et al., 1997). However, withdrawal signs have been described in animals treated chronically with cannabinoids and then given one of the new receptor antagonists (Aceto et al., 1995; Tsou et al., 1995).