The media response to Coffey et al (Reference Coffey, Carlin and Lynskey2003) was predictable. ‘Anti-drug campaigners say new research, showing one in three teenagers who smokes cannabis weekly becomes hooked by their early 20s, proves that it should not be treated as a “soft” drug. The shocking study found teens who used cannabis every week were at high risk of addiction’ (Reference LawrenceLawrence, 2003). Coffey is quoted as saying, ‘The message here is that cannabis is not as harmless as we had thought earlier’ – an amazing conclusion from a study where only 1% of the respondents identified as dependent reported social consequences of their use, while the most prevalent symptom (10%) was persistent desire. In everyday parlance, they smoked because they liked it.

Use of the very broad categorisations of the DSM is especially worrisome. Clinicians using these guidelines apply them to people presenting with problems. The use of such categorisations in research, however, constitutes imprecise criteria to determine a person's dependence, resulting in the phenomenon being grossly overreported.

Researchers have been able to generate dependency by applying these same criteria to behaviours as diverse as jogging, shopping, sex, prayer and mountain climbing. In fact, these activities were found to be as addictive as cannabis (Reference FranklinFranklin, 1990).

Problems include the disjunctive nature of the criteria (dependency can be ascribed to two people with absolutely no symptoms in common), and the essentially subjective way in which the characteristics are defined. The lack of specificity in the measurement of cannabis dependence results in subjective measures being presented as objective and an over-reliance on the interpretive framework brought to bear. How did the authors differentiate between ‘wants’ and what DSM characterises as ‘needs’? Was this differentiation communicated to respondents? The study fails to differentiate respondents with no dysfunction associated with their dependence from those with significant cannabis-related problems.

Finally, the only index of consumption employed is frequency of use. This is most unsatisfactory; a ‘smoke’ is not a standardised measure and the consequent lack of any demonstrable association between tetrahydrocannabinol consumption and the dependence syndrome begs the question, dependent on what? Preparing a joint? Inhaling deeply?