Smoking weed won’t make your kids smarter, but it won’t make them brain-dead, either

Diet & Fitness, Mind

24th October 2014

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I don’t want this to become the ‘Tom Tells You To Get High’ blog, so this will be the last time I write about cannabis for awhile, I promise. Unless there’s something interesting in the news about it again.

Anyway, pass the dutchie on the left-hand side and all that. The Daily Mail, the BBC and the Telegraph report that teenagers who smoke cannabis regularly do worse in their exams. Per the Mail:

‘The findings. . . add to a growing weight of evidence that suggests cannabis is more harmful than legalisation campaigners would have us believe’.

They’re half right. Teenagers who smoke cannabis regularly do tend to do worse in their exams. But the findings in no way suggest that cannabis is more harmful than we thought. (We already thought it was a bit harmful, by the way.)

If you make it down to paragraph 19 (literally) of the Mail’s version, in fact, the story debunks itself. The Mail quotes the UCL study’s lead researcher Claire Mokrysz, who says:

‘It’s hard to know what causes what – do kids do badly at school because they are smoking weed, or do they smoke weed because they’re doing badly? This study suggests it is not as simple as saying cannabis is the problem.’

Mokrysz, in quotes that the Mail didn’t use, goes further, saying that the study

‘may suggest that previous research findings showing poorer cognitive performance in cannabis users may have resulted from the lifestyle, behaviour and personal history typically associated with cannabis use, rather than cannabis use itself.’

Only in the very heaviest cannabis users was any association found at all: they scored 3 per cent lower on school tests at age 16 than did their peers, apparently, even after controlling for other factors – although it had no effect on their IQ. So not only does the research fail to ‘add to a growing weight of evidence’, the study actually says that the evidence so far may overstate the real dangers.

(On a side note, the study says that the only factor that was strongly associated with mental impairment was alcohol use. ‘No other factors were found to be predictive of IQ change.’)

As always: no one is suggesting that cannabis is good for you, or good for your brain, especially in large doses. But a sensible discussion of the real evidence is preferable to a daft ‘reefer madness’ scare.