cannabis is bad mmmkay

[andyandy]

Mr Garrison was right....

Smoking cannabis increases the risk of schizophrenia by at least 40% according to research which indicates that there are at least 800 people suffering serious psychosis in the UK after smoking the drug.
snip
The overall additional risk to cannabis smokers is small, but measurable. One in 100 of the general population have a chance of developing severe schizophrenia; that rises to 1.4 in 100 for people who have smoked cannabis.

But the risk of developing other psychotic symptoms among people who smoke large quantities or are already prone to mental illness is significant, the researchers say.

People who smoke cannabis daily have a 200% increased risk of psychosis. They estimate that 14% of 15- to 34-year-olds currently suffering schizophrenia are ill because they smoked cannabis, a figure previously thought to be between 8% and 10%. According to the current diagnosis rates about 800 people would have been spared schizophrenia if they had not smoked cannabis.

The researchers said the evidence was the strongest yet to show that cannabis caused psychotic mental illnesses, and not just that people who were ill smoked more. Dr Stanley Zammit, of Cardiff University, said: "We think the evidence is such that we need a new official warning about the risk."

http://society.guardian.co.uk/drugsandalcohol/story/0,,2135991,00.html

pdf of the lancet article here

and more on the study in the NS

Previous research has suggested a link between cannabis and schizophrenia-like symptoms such as paranoia, hearing voices and seeing things that are not there. But the possible association "has been an issue of tremendous debate and controversy for a long time", says Rick Rawson, a professor at the University of California in Los Angeles, US. "The science gets all mixed together with all the ideological views [about the drug]."

Now, researchers in the UK have reviewed 35 studies on the long-term effects of cannabis use in Europe, the US and Australasia and say the drug does in fact appear to be linked with an increased risk of psychosis. The original studies lasted from one to 27 years.

Because people with pre-existing mental health problems may be more likely to take drugs in the first place, the researchers excluded data from those already showing signs of psychotic illness. Still, they found an increased incidence of psychosis in cannabis users, suggesting the drug may somehow cause such disorders, they say.

"Although you cannot be certain that the cannabis is causing this increase in risk, we think there is enough evidence to warn people," team member Glyn Lewis of the University of Bristol in the UK told New Scientist.

If cannabis does cause psychosis, it could account for at least one in every 10 cases of diagnosed psychotic illness, the researchers say.

"There is a very good reason to be concerned," says Shaul Hestrin of Stanford University in California, US, who is investigating how cannabis-like substances affect brain cells. He says the evidence of a causal link in this latest study is "very convincing" but adds that even better evidence may come once scientists understand how cannabis actually changes the brain.

Rawson agrees: "The big question is how to determine who's at risk."

http://www.newscientist.com/article/dn12363-cannabis-use-increases-risk-of-psychotic-illness.html

Interesting meta-analysis which seems to give further evidence to the mental health/cannabis link.

Also in this weeks NS - adolscent rats have been shown to be more attracted than adult rats to cannabis - and more suceptible to the drug's effects on memory.

Adolescent rats are more likely than adults to be attracted by cannabis - and seem more susceptible to the drug's effects on memory.Over a period of 18 days, Iain McGregor at the University of Sydney, Australia, and colleagues injected rats with tetrahydrocannabinol (THC), the active ingredient in cannabis, at doses designed to mimic heavy cannabis use in humans.

Two weeks after the final dose, the adult rats avoided the regions of the testing chamber where they had received injections, but the adolescents showed no such aversion. This suggests that the adult rats found the THC unpleasant, while the adolescents didn't, says McGregor.

Also unlike the adults, the adolescents had lasting problems with short-term memory. When the team examined the hippocampus region of the brain, they found changes to many more proteins in the brains of the adolescents, compared with the adults. The researchers point out that adolescent brains are still maturing, and say they seem to be more vulnerable to THC (Neuropsychopharmacology, DOI: 10.1038/sj.npp.1301475).

and another study which shows adolescent effects on brain chemistry.

Now research in rats suggests that using marijuana reduces future sensitivity to opioids, which makes people more vulnerable to heroin addiction later in life. It does so by altering the brain chemistry of marijuana users, say the researchers.

snip

"Teenage" rats
In order to explore how the adolescent use of cannabis affects later drug use, Hurd and colleagues set up an experiment in rats aimed to mirror human use as closely as possible.

In the first part of the trial, six “teenage” rats were given a small dose of THC – the active chemical in cannabis – every three days between the ages of 28 and 49 days, which is the equivalent of human ages 12 to 18. The amount of THC given was roughly equivalent to a human smoking one joint every three days, Hurd explains. A control group of six rats did not receive THC.

One week after the first part was completed, catheters were inserted in all 12 of the adult rats and they were able to self-administer heroin by pushing a lever.

“At first, all the rats behaved the same and began to self-administer heroin frequently,” says Hurd. “But after a while, they stabilised their daily intake at a certain level. We saw that the ones that had been on THC as teenagers stabilised their intake at a much higher level than the others – they appeared to be less sensitive to the effects of heroin. And this continued throughout their lives.”

Hurd says reduced sensitivity to the heroin means the rats take larger doses, which has been shown to increase the risk of addiction.

http://www.newscientist.com/article.ns?id=dn9488

quite a few studies all out at the same time.....

 

[Broes]

Yeah, cannabis is very very dangerous.

However, have you ever see the test reports what alcohol and tabacco can do to you? I wonder why that stuff even gets sold

Bruce

 

[Molinaro]

"Although you cannot be certain that the cannabis is causing this increase in risk, ..

Were going to warn you anyway.

 

[andyandy]

Yeah, cannabis is very very dangerous.

However, have you ever see the test reports what alcohol and tabacco can do to you? I wonder why that stuff even gets sold

Bruce

Surely it is possible to acknowledge new studies with regards to cannabis without the "look at alcohol that's legal and that's more dangerous" kind of comments? No one has said cannabis is very very dangerous, no one has said that it is more dangerous than alcohol or tobacco - the strawmen you wish to roll your eyes at are of your own creation.
FWIW I still think cannabis should be legalised - not because it's harmless but because it could be much better regulated.

 

[andyandy]

"Although you cannot be certain that the cannabis is causing this increase in risk, ..

Bruce

if you demand certainty from scientists then you'll rarely be satisfied. A much more realistic bar is that of significance - and the lancet study showing 40% increased likelihood, controlled for other factors, is with a 95% confidence interval.

 

[Puppycow]

I agree that it is bad, although I still think that society would be better off if drugs were legalized but heavily taxed and regulated. Strictly no advertising. Monotone packaging like prescription medication; no eye-candy. Hard stuff like heroin and cocaine only available at a pharmacist. All coming with warnings about all the risks. Tax revenues used to offset health consequences and other social consequences, and pay for education to warn children and adolescents of the risks. I believe that such an approach would result in similar levels of abuse to the current regime, but would be less expensive to enforce and less punitive.

 

[Molinaro]

if you demand certainty from scientists then you'll rarely be satisfied. A much more realistic bar is that of significance - and the lancet study showing 40% increased likelihood, controlled for other factors, is with a 95% confidence interval.

I'm not looking for certainty. I thought that perhaps this story would be less qualified that those that have come before.

 

[casebro]

"the researchers excluded data from those already showing signs of psychotic illness."

Yeah, sure. Just how many young subjects of all of those studied had had a psychological work up? I'd say that pre-existing conditions were mostly unknown, and so were inadequately controlled for. You know the cannabis euphoria has to appeal to lots of folks who are self-medicating their problems away.

I'll bet the same type of study would give similar results for alcohol, gambling, smoking, or thrill seeking. I see the headlines now- "Schizophrenia caused by riding roller coasters" or even "Schizophrenia caused by too much sex" or any other addictive behavior.

How about a study re: "Does schizophrenia cause addictive behavior?" I'm not going to bother looking it up, it's too obvious. I'm sure it's out there.

 

[Dabljuh]

post hoc, ergo propter hoc?

 

[andyandy]

"the researchers excluded data from those already showing signs of psychotic illness."

Yeah, sure. Just how many young subjects of all of those studied had had a psychological work up? I'd say that pre-existing conditions were mostly unknown, and so were inadequately controlled for. You know the cannabis euphoria has to appeal to lots of folks who are self-medicating their problems away.

Have you read the study? They do discuss the considerations/limitations in detail....

 

[tuc0]

Yeah, it's all over the news today. I guess it's plausible that any mind-affecting substance can influence the probability of being afflicted by a strange condition of the mind... duh. However I'm always quite skeptical of studies that try to assign "probabilities" to such individual (and still not quite understood) phenomena as psychoses.
The animal studies are much more interesting imho.

 

[Skepticybe]

I just love when these studies ignore the difference between correlation and causation.

So the researchers have found a correlation between marijuana use and mental illness. OK, let's accept that.

Would it surprise anyone to learn that people who are more prone to mental illness would tend to be more troubled individuals, and would be more likely to take up marijuana and other drugs? Would it surprise you to learn that among those who use marijuana, those who are prone to mental illness tend to use it more heavily? It would be news if this wasn't the case.

Controlling for this factor in a study would be exceptionally difficult, not to mention contrary to the desired (I would even go so far as to say required) outcome of the study. When it comes to marijuana, science is trumped by the political agenda and superstition.

Also, the FoxNews report included the following:
http://www.foxnews.com/story/0,2933,291043,00.html

Two of the authors of the study were invited experts on the Advisory Council on the Misuse of Drugs Cannabis Review in 2005. Several authors reported being paid to attend drug company-sponsored meetings related to marijuana, and one received consulting fees from companies that make antipsychotic medications.

 

[Skepticybe]

I would love to see the results of the same study methodology applied to:

tobacco
alcohol
cocaine
prescription drugs that are commonly abused

What do you want to bet those studies would produce similar results?

 

[Father Dagon]

I agree that it is bad, although I still think that society would be better off if drugs were legalized but heavily taxed and regulated.

Heavy taxes will only create a market for the organized and not-so-organized crime.

 

[JoeEllison]

Surely it is possible to acknowledge new studies with regards to cannabis without the "look at alcohol that's legal and that's more dangerous" kind of comments? No one has said cannabis is very very dangerous, no one has said that it is more dangerous than alcohol or tobacco - the strawmen you wish to roll your eyes at are of your own creation.
FWIW I still think cannabis should be legalised - not because it's harmless but because it could be much better regulated.

No, it doesn't seem possible.

 

[vexed]

Heavy taxes will only create a market for the organized and not-so-organized crime.

As in there isn't a market right now? I buy my weed from illegal markets, just wish the voices would stop!!!

 

[Drudgewire]

If anyone has tried the specialty strains going around (got some white widow currently), they know it's pretty much worth any psychosis down the line.

 

[Skepticybe]

No one has said cannabis is very very dangerous, no one has said that it is more dangerous than alcohol or tobacco

I don't know where you live, but growing up I heard this constantly and my teenage kids hear the same thing now. It was, and is, standard practice to say whatever it takes to keep kids away from marijuana.

The official message is that cannabis is very very dangerous, more so than even alcohol or tobacco. Just last month I saw the head of the DEA on TV talking about "Pot 2.0" and how it is many times more dangerous because of the very potent strains now available. This is an outright lie; more potent pot means less needs to be smoked for the same dose, reducing stress on the lungs.

Can you imagine the head of the DEA going on TV to announce that pot is now safer because it is more potent and less needs to be smoked for a dose? That's when we know science is winning.

 

[Ziggurat]

if you demand certainty from scientists then you'll rarely be satisfied. A much more realistic bar is that of significance - and the lancet study showing 40% increased likelihood, controlled for other factors, is with a 95% confidence interval.

I think your understanding of the meaning of confidence interval is wrong, because your statement here doesn't make sense. You can establish a 95% confidence interval on pretty much any statistically derived quantity. The 95% isn't what indicates strong confidence (it's an arbitrarily chosen percentage, and confidence intervals exist for any other percentage you wanted to pick as well), it's the size of the interval covered by this 95% certainty which does, and you didn't list it. From your link, it appears that the 95% confidence interval is 20%-65% increased risk, so it looks like an increased risk is significant (assuming they didn't screw up somehow), but you need to say what the size of the confidence interval is, saying that it's 95% doesn't actually convey any information.

 

[Deetee]

Also, the FoxNews report included the following:
http://www.foxnews.com/story/0,2933,291043,00.html
Two of the authors of the study were invited experts on the Advisory Council on the Misuse of Drugs Cannabis Review in 2005. Several authors reported being paid to attend drug company-sponsored meetings related to marijuana, and one received consulting fees from companies that make antipsychotic medications.

Except this is not a conflict of interest at all.
These authors are warning about the increased risks, so presumably the logically expected result of their warning will be a decrease cannabis use, and a decrease the incidence of illness requiring antipsychotic medication.
They risk biting the hand that feeds them.