The northlondonhippy

My friends at the Guardian news­pa­per are giv­ing me hope that the truth in the debate about cannabis reclas­si­fi­ca­tion will be an hon­est one. The gov­ern­ment can’t ignore the facts and only quote the lies.

As you’ve no doubt read or heard, the well-known British med­ical jour­nal, The Lancet, has recently pub­lished a study into the effects of cannabis use. Rather than try to debunk the ques­tion­able sci­ence and research tech­niques used in prepar­ing this report myself, I would pre­fer to share an arti­cle from the Sci­ence sec­tion of the Guardian.

Here it is, with a link to the orig­i­nal and the full text. If the Guardian objects to me post­ing the full text, please feel free to con­tact me, ask­ing for its removal. I will keep the link back to the orig­i­nal though.

==========
http://www.guardian.co.uk/science/2007/jul/28/drugs.drugsandalcohol

“Cannabis data comes to the crunch

by Ben Goldacre

Sat­ur­day July 28 2007

You know when cannabis hits the news you’re in for a bit of fun, and this week’s story about cannabis caus­ing psy­chosis was no excep­tion. The paper was a sys­tem­atic review and then a “meta-analysis” of the data which has already been col­lected, look­ing at whether peo­ple who smoke cannabis are sub­se­quently more likely to have symp­toms of “psy­chosis” or diag­noses of schiz­o­phre­nia. Meta-analysis is, sim­ply, where you gather together all of the num­bers from all the stud­ies you can find into one big spread­sheet, and do one big cal­cu­la­tion on all of them at once, to get the most sta­tis­ti­cally pow­er­ful result possible.

Now I don’t like to carp, but it’s inter­est­ing that the Daily Mail got even these basics wrong, under their head­line “Smok­ing just one cannabis joint raises dan­ger of men­tal ill­ness by 40%”. Firstly “the researchers, from four British uni­ver­si­ties, analysed the results of 35 stud­ies into cannabis use from around the world. This sug­gested that try­ing cannabis only once was enough to raise the risk of schiz­o­phre­nia by 41%.”

In fact they iden­ti­fied 175 stud­ies which might have been rel­e­vant, but on read­ing them, it turned out that there were just 11 rel­e­vant papers, describ­ing seven actual datasets. The Mail made this fig­ure up to “35 stud­ies” by includ­ing 24 sep­a­rate papers which the authors also found on cannabis and depres­sion, although the Mail didn’t men­tion depres­sion at all.

They also said that “pre­vi­ous stud­ies have shown a clear link between cannabis use in the teenage years and men­tal ill­ness in later life”. They then described some of these pre­vi­ous stud­ies. These were the very stud­ies that are sum­marised in the new Lancet paper.

But what was left out is as inter­est­ing as what was added in. The authors were clear — as they always are — that there were prob­lems with a black-and-white inter­pre­ta­tion of their data, and that cause and effect could not be stated sim­ply. For ongo­ing daily users, as an exam­ple, it’s dif­fi­cult to be clear that cannabis is caus­ing peo­ple to have a men­tal ill­ness, because their symp­toms may sim­ply be due to being high on cannabis all the time. Per­haps they’d be fine if they were clean.

It was also inter­est­ing to see how the risk was numer­i­cally reported. The most dra­matic fig­ure is always the “rel­a­tive risk increase”, or rather: “cannabis dou­bles the risk of psy­chosis”, “cannabis increases the risk by 40%”. Because schiz­o­phre­nia is com­par­a­tively rare, trans­lated this into real num­bers this works out — if the fig­ures in the paper are cor­rect, and causal­ity is accepted — that about 800 yearly cases of schiz­o­phre­nia are attrib­ut­able to cannabis. This is not belit­tling the risk, merely express­ing it clearly.

But what’s really impor­tant, of course, is what you do with this data. Firstly, you can mis­p­re­sent it, and scare peo­ple. Obvi­ously it feels great to be so self-righteous, but peo­ple will stop tak­ing you seri­ously. After all, you’re talk­ing to a pop­u­la­tion of young peo­ple who have worked out that you rou­tinely exag­ger­ate the dan­gers of drugs, not least of all with the ridicu­lous “mod­ern cannabis is 25 times stronger” fab­ri­ca­tion so beloved by the media and politicians.

And cra­zi­est of all is the fan­tasy that reclas­si­fy­ing cannabis will stop six mil­lion peo­ple smok­ing it, and so erad­i­cate those 800 extra cases of psy­chosis. If any­thing, for all drugs, increased pro­hi­bi­tion may cre­ate mar­ket con­di­tions where more con­cen­trated and dan­ger­ous forms are more com­mer­cially viable. We’re talk­ing about com­mu­ni­ties, and mar­kets, with peo­ple in them, after all: not mol­e­cules and neu­rore­cep­tors.”
==========

As you can see, the hype and hys­te­ria is in over­drive, but the truth is there, if peo­ple choose to share it with you.

My pur­pose at the moment, is to bring you all the truth on the sub­ject, in the hopes that we can all make an informed deci­sion. And yes, I’m talk­ing to you, Mr. Politi­cian Man! Do what’s right, not what you think peo­ple want you to do out of mis­placed and ill-informed fear.

Comments are closed.