Erikka Askeland: Cannabis study on IQ raises pot of issues

Everything is bad for you. Wine, milk, working mothers, breakfast cereal – and don’t even start on the bacon.

Some of the horror stories you read about the health effects of delicious strips of cured pork might put you off the stuff until pigs fly.

For the most part, reports of health studies should be taken with a pinch of salt – except that probably isn’t terribly wholesome either. As often as you hear a report about how certain foods, such as eggs are healthy because they are full of nutrients and protein, there is a competing argument that their high cholesterol content will give you a heart attack.

Hide Ad
Hide Ad

Even organic vegetables have been subject to scare stories, which makes you think there’s nothing you can consume with impunity. Reading such reports tends to render the science behind the findings like so much pablum – bland fare you hardly notice and might actually not be that good for you to consume.

But a recent study on the effects of smoking marijuana gave me pause. As far as studies went, it had breadth and depth, tracing 1,000 people for close to 40 years. It found that smoking pot before the age of 18 reduced 
intelligence.

I’m sure I wasn’t the only one to think on hearing the report on morning radio, “oh hell”.

Now this admission may ruin any, admittedly slim, chances I have running for public office, but I inhaled. And while I further put myself at risk of having my IQ the subject of malign speculation, I also partook of the occasional spliff before I was 18.

Suffice it to say, where I come from, weed is so plentiful even my grandma knew what a grow-op was. (It’s a marijuana-growing operation, for those without my grandma’s street credibility). And it wasn’t just the misguided youth who were at it. I also knew of health workers, administrators and even police officers who occasionally indulged as well.

But further reading of the report made me feel much better. Because while I was far from being an angel in my teens, the research says the loss of brain cells is most noticeable in chronic, near-daily users of the drug – what we in my time would have referred to as stoners. They were the guys – usually they were boys – always sniggering about weed, always trying to score weed and who usually bunked off school to do so. That there is now research suggesting these guys maybe weren’t the brightest sack of hammers, in retrospect, comes as no real surprise.

The interesting question is why it is the case that cannabis has this effect on younger folk, and not the over-18s. Some figure it is because the adolescent brain, far from being just a younger, adult version, is undergoing rapid change. While you may think teenagers are just being feckless, sullen and foolhardy, in fact their synapses are being subject to what could be described as a ruthless pruning. This process shapes them to become sensible, efficient mature brains – with the final section of the noggin to be fully formed being the part that oversees impulse control. Add too much cannabis to that and you have a recipe for being permanently addled, or, depending on what you smoked, at least something tasty for when you get the munchies.

And while the science is beyond reproach, the results of the cohort study still gives rise to questions. Previous studies have linked chronic cannabis smoking, particularly of stronger strains of the drug, with psychosis or schizophrenia. But it is still up for argument whether people with a tendency to mental illness smoke more pot. Likewise the Dunedin Multidisciplinary Health and Development Study, while ground-breaking, might also not have ruled out other factors, such as depression, that might have driven some of its subjects to endless toking and a resulting reduced IQ.

Hide Ad
Hide Ad

Ugo Uche, a psychotherapist who blogs on the Psychology Today website, questioned the study’s reliance on intelligence tests, which many consider to be a blunt instrument. He suggested that most of the people he works with who habitually use the drug lack problem solving skills “most likely due to the fact that during their period of using they are not noticing their problems”.

What might be of interest is that at least one of the study’s backers suggested that cannabis was actually safe for over-18s, or at least, probably no worse than a few glasses of wine. With evidence of marijuana use stretching back millennia, it is clear that the drive to get a bit blootered has long been with us. But here is compelling evidence that you might want to confiscate the teenager’s stash at least until they are older.