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  Addiction journal Feb 2007 lead editorial: questionable logic.

Posted: May 16, 2007 14:17

Addiction 2007 102:173-176

Pollack HA, Reuter P. The implications of recent findings on the link between cannabis and psychosis.

Just when we thought the last word was in on this issue, the Addiction journal has its lead editorial as a poorly written, confused 'hypothetical' on cannabis and psychosis. It seriously concludes (with no evidence quoted) that cannabis might just turn out to be much more harmful than was 'thought' (they don't say by whom), needing new policies to restrict its use. Rather than being a balanced review of this interesting if less than earth-shattering issue, we find two respected authors speculating a worst-case scenario should research prove cannabis to be much more harmful than previously believed. They contradict themselves by reiterating at least three times that law enforcement has little impact on consumption, yet at the same time, assuming a 20% drop can be obtained using certain (unspecified) punitive measures.

Despite being in a European journal, here we have a uniquely American or 'drug war' perspective given equal footing alongside scientific or evidence-based approaches with which these authors are obviously familiar but unwilling to address in parallel with their current subject.

Despite the wild speculation about possible unexpected dangers, the authors completely ignore the fact that doctors prescribed this drug for much of the 20th century with few adverse consequences reported. They also completely ignore the Dutch experience where cannabis has been available for adults to purchase for many years with low community rates of cannabis use (especially in the young) and few adverse events. Equally, they ignore the lack of any reported increased prevalence of psychosis in areas of very high cannabis use.

Their alarmist speculation might make some sense if this were a newly introduced drug, but it has been used for generations and is unlikely to show up completely unexpected adverse effects on which these authors speculate. Indeed no cannabis deaths have ever been reported while most other drugs, even seemingly innocuous ones, have a reported mortality (penicillin, aspirin, MDMA).

Despite mentioning the relative harms, known and unknown, of cannabis, the authors at no point try to put these harms into context of other drugs such as alcohol, tobacco, ecstasy, cocaine, etc. If they had, readers may realise that quite contrary to their stated logic, the more dangerous a drug is, the more cogent the argument that it be controlled or even supplied by the state. Under this system, substantial reductions have been made in consumption of alcohol and tobacco in many western countries.

Perhaps predictably, these authors ignore the possible benefits from cannabis. Just as alcohol probably has some benefits for certain groups, so, along with possible prescription use, cannabis availability might result in net benefits to certain users and even society generally. One feasible means might be through reductions in the use of other more dangerous drugs such as alcohol and tranquillizers.

I read on, expectantly waiting for some new reports of a link between cannabis and psychosis but there was none such. They vacillate from calling the drug 'marijuana' to the correct medical term, cannabis, as in their title.

These authors bemoan a lack of longitudinal research including cannabis, yet they fail to cite Fergusson's landmark reports on the subject which are both detailed and comprehensive.

Fergusson has reported a probable association and a possible causative link between cannabis use and a small proportion of psychosis cases. He feels that the jury is still out, but that the numbers are not large. Neither he nor these authors express any great faith in legal constraints in reducing cannabis use. Despite this, the Addiction authors bring up a ludicrous hypothetical of cost-benefit relation between a 20% reduction in cannabis use and savings to society by a purported 1.6% reduction in schizophrenia cases. They freely admit the difficulties of measuring consequences of criminal convictions such as family breakdown, work and education disruption, not to mention the occasional cases of long-term residents being deported to unfamiliar third world countries as a 'double punishment' which is not unheard of nowadays. Adding to their delusion, these authors try to persuade the reader that while most countries would be unlikely to agree to increase penalties for cannabis use or possession, they propose that the USA is the most likely country to do so!!

It is hard to understand the rationale behind this editorial. Does Addiction peer review (or even proof read) their editorials?

The rest of this edition has an array of interesting and relevant articles if one is not put off by the first three pages of drivel.

Comments by Andrew Byrne ..



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