Thursday, August 13, 2009

NCPIC reviews cannabis-driving with mixed results

A quick read of the evidence behind a new campaign from the National Cannabis Prevention and Information Centre (NCPIC) reveals nothing new, although lurid posters to be circulated throughout schools bely the mixed results of the brief evidence review.

I have long wondered about the facts of this issue when I compare such reports with decades of observing drunks often pranging cars and smokers generally not. I have noticed that laboratory studies usually demonstrate higher risk but population studies don't -- and this report reflects that observation.

I would be interested in the views of others. Comments are open below!

I am automatically suspicious of anything that comes out of NCPIC, which seems to have a mission to demonise cannabis and so-far has a woeful record of amplifying junk science. The new campaign seems much more considered.

However I note a drastic disconnect between the lurid posters they will be flooding schools with, and the conclusion of the research, which begins:
There are numerous methodological limitations in the studies reviewed above that may account for the great variations and inconsistencies in their findings, which detracts from the likelihood of a clear synthesis of results.
When in doubt, demonise, seems the continuing NCPIC policy. The posters say smoking is as bad as drinking but it isn't.

The conclusion also speaks about developing new guidelines for cannabis/driving research. I have long thought that a large population study could provide a clearer answer. Take 1,000 or more long-term users (with, say three decades of smoking cannabis) and the same number of people who have never smoked. Then compare their driving and crash records. The study could also look at other factors such as health history, employment, family dynamics, social factors and the like.

Some things I note about the NCPIC report:

• It is not clear whether alcohol has been eliminated as a confounding factor for car accidents in the various population studies.

• Where studies show a percentage of injured drivers testing positive for cannabis, this percentage often seems to be below the percentage of the population which uses cannabis -- so is this statistically significant? There is also a drastic diversity of results from different studies, which makes me wonder about the alcohol factor.

• A common belief among counter-cultures which use cannabis is that the well-known 'paranoid' effects of cannabis cause drivers to be extra-cautious when driving while its other effects make them less aggressive and more relaxed. The old joke about the hippies being pulled over for driving at half the speed limit is legion. This could explain why the laboratory and driving simulator tests show such different results.

• While it is no doubt prudent to advise young people NOT to drive under the influence of cannabis (especially for inexperienced drivers, I would think), this report will be used to justify more drug-testing of drivers who will be penalised at the same levels as for drunk driving when the risk they pose to others is far lower.

The effects of drunk driving are clear, and observable anecdotally. The effects of cannabis driving are not. The report will also be gleefully brandished by prohibitionists to support their failed regime.


Anonymous said...

My memory of the various bits of research over the last two decades is consistent with your general view. While there appears to be a very clear and unavoidable link between alcohol intoxication and driving impairment, there is no clear linkage between cannabis and driving. Some cannabis users are impaired, some are unaffected, and some have their driving improved.

Overall there wasn't enough of a link to justify any law against "cannabis driving". That inconvenient fact has been ignored in the last few years.

Cannabis Man said...

I thought this link to a UK study would be useful for this subject.

The Editor said...

The video linked above on the 'I am bored' site had been 'removed due to terms of use violation'. What was on the video? It was about smoking cannabis and driving -- was it censored by Big Nanny because it 'sent the wrong message' by showing people having clean. safe fun? Or was it a horror video showing stoners having horrible smashes like the one the Victorian Government is currently circulating to schoolkids?

Cannabis Man said...

sorry man here is a new link you cant take it off the net once its on :)