Thursday, 5 June 2008

Junk Science, Cannabis and the ABC

It’s not everyday I find a blog with an article that I wish I had written. The Kings Cross Times wrote a piece about a tragic case of drug hysteria that should be read by everyone. 

ABC Joins Uncritical Panic Over Cannabis

"Psychiatrists have known for years that there is nothing soft about the drug cannabis," gushed the reporter headlining her story on the ABC's AM program this morning.

She was talking about a study of 15 men who had smoked at least five joints a day for ten years. The men showed a shrinkage of certain parts of their brains and, not surprisingly, had reduced memory performance. The results were compared to minor brain injury trauma (like boxers get, legally, all the time).

This seems typical of recent output from the prohibition industry – reductive research setting out to find harm (otherwise they don't get funded), using a tiny sample and guaranteeing headlines from uncritical media, resulting in professional kudos. It creates alarm in the uninformed public and is used by prohibitionists to justify their position, no-one apparently noticing that all this drug abuse demonstrates that prohibition is not working.

Five joints a day for ten years might be similar to drinking two bottles of vodka a day or perhaps eating ten carrots a day, both of which would probably cause harm to the abuser. This does not justify gushing headlines that carrots 'are not a soft drug'.

And where would they find 15 guys who consumed that much pot? They must be very unusual people, almost certainly among the 4.5% of the population who are unemployed. I'll bet they also smoke tobacco and drink, although the researchers say they matched the control group for other factors. I would guess they have other precursor problems, and I'll bet this minor study had not scanned their brains before the ten-year period, either. And how did they conclude, from this atypical sample, that 'any amount' of smoking put the person at risk?

And now the researcher, Marat Yucel from Melbourne University, is on 702's Morning Show trotting out a lone 20-year-old ex-smoker, who was not even in the study but is part of a tiny minority who had a bad time on it. Standard tactics. But it will look good on Yucel's CV.

At least AM quoted Gino Vumbaca from ADCA who cautioned about the small sample used in the study.

Ah, Yucel just admitted that all the smokers in the sample were unemployed and the control group wasn't. And now he's COMPLETELY lost it, comparing the occasional tobacco smoker who lives for a hundred years to the 90% plus of cannabis smokers who don't experience significant problems. Host Deborah Cameron missed that glaring fallacy, though.

Meanwhile the potentially $120 million worth of ice lost by police (see previous post) remains out there on the black market and the media are ignoring this massive failure of prohibition. Their news sense is definitely lost in the moral panic.

-Kings Cross Times:  ABC Joins Uncritical Panic Over Cannabis

One reader provided a link to a New Scientist article that backed up the Kings Cross Times article.

A Spliff Test for Science

It's the oldest but most important scientific question when two phenomena appear related: does one cause the other, vice versa, or is the apparent relationship pure coincidence? The question came up again this week when an Australian study demonstrated that 15 men who had all smoked marijuana heavily for at least 10 years had shrunken brain structures compared to those in non-users.

So was it the cannabis that on average shrank their hippocampuses by 12% and their amygdalas by 7%? Or were these same regions small to start with in these men, and if so, was it something that played a part in their strong liking for cannabis?

Certainly, both these regions are heavily affected by cannabis because they are both unusually rich in molecular receptors for delta-9-tetrahydrocannibol (THC), the psychoactive component in weed. The hippocampus is vital for storing memories and for the perception of time, and marijuana is known to affect both. Likewise, the amygdala is the brain's "fear" centre, and plays a key role in whether we react aggressively to events. Again, this fits with the observation that cannabis users sometimes develop paranoia.

To come back to the Australia study, is it equally possible that such prolonged exposure to cannabis wears out and shrinks these cannabis-sensitive regions? Again, we're back to cause and effect.

The only way to resolve it once and for all (as pointed out by the Australian researchers themselves at the end of their paper) would be to have brain scans of people before and after they began smoking cannabis. That way, you could see whether these regions did actually shrink the more cannabis they were exposed to. Or whether some people with unusually small regions at the outset turned out to be more attracted to the weed.

Unfortunately, a study to find out by deliberately giving cannabis to volunteers then following them for many years to see if their brains shrank would be unethical. Ethical comparisons could only be done if scans had been performed randomly on a wide population of children and kept as a general resource for researchers. If any of the scanned children subsequently became heavy dope users, it would be easy to check back and monitor whether brain regions were changing size. But obtaining the scans would cost a huge amount of money without any guarantee that it would yield any findings of interest.

So for now, we simply don't know for sure whether cannabis is genuinely changing brain architecture. And the same dilemmas apply to study of all addictions. Which is why some researchers contacted by New Scientist cautioned against sensationalising the Australian results.

"You must be very careful looking at this paper in isolation," says Tim Williams, who studies addiction at the University of Bristol. "With this kind of study, you can't tease out cause and effect." Williams also pointed out that a study in 2005 of long-term cannabis users by researchers at Harvard Medical School found that there was no effect on the size of their hippocampuses. "I'm surprised the Australians found an effect where others haven't," he adds.

The take-home message is clear! Be cautious about concluding too much from addiction studies which might confuse cause and effect. Yes, it could be down to the drug, but equally, it could be down to your pre-existing brain architecture, and the effect of that on your personality.

-Andy Coghlan, New Scientist reporter

The comments from some readers summed up the issue.

The fact that this study is at odds with other studies that don't show shrunken hippocampuses seems to suggests that the study can't be conclusive - but should be further investiagted.

Critics are rightly pointing-out that a correlation isn't the same as causal.

Further, critics are citing (see other NS article commentary) possible overlooked effects of nicotine and carbon monoxide on subjects brain structure. 

Do Australian cannabis smokers smoke more tobacco with their cannabis? ...and could this explain the variation from other countries studies? Given that nicotine has been identified as a destroying brain tissue it's possible. 

The effects of THC on brain structure needs to be teased out - with all types of groups (cannabis eating only group, non tobacco cannabis smokers etc) - with before and afters. Yes, it's hard to create that.

...And an honest researcher would say that it's very hard to come to any conclusions without such a comprehensive study. So was this politicized science?

-By  Anonymous 

and this.

Did they control for alcohol use/abuse, other drugs, environmental factors, or genetics? If not, then this study is next to meaningless. The ridiculously small sample size doesn't help either, statistically speaking.

Even if it were true, what percentage of regular pot smokers smokes 5 joints a day for 10 years or more? If pot does affect the size of certain parts of the brain, do those effects disappear after usage stops? These are the things that a real study would have looked into.

-By Ozzy OG Kush

4 comments:

Jack Dorf said...

By now Terry we should all realise that there is nothing like a "drugs R bad" story to get a journalist pumping out the Jenkem

Terry Wright said...

Thanks Jack.

That's unbelievable!

If this doesn't prove that some people are always going to get high no matter what, nothing will.

phallacy said...

"post hoc ergo propter hoc"

Terry Wright said...

Thanks Phallacy.

I had to look that one up!