Cannabis use precedes the onset of psychotic symptoms in young people

Mar 01, 2011

Cannabis use during adolescence and young adulthood increases the risk of psychotic symptoms, while continued cannabis use may increase the risk for psychotic disorder in later life, concludes a new study published in the British Medical Journal today.

Cannabis is the most commonly used illicit drug in the world, particularly among adolescents, and is consistently linked with an increased risk for mental illness. However, it is not clear whether the link between cannabis and is causal, or whether it is because people with psychosis use cannabis to self medicate their symptoms.

So a team of researchers, led by Professor Jim van Os from Maastricht University in the Netherlands, set out to investigate the association between cannabis use and the incidence and persistence of over 10 years.

The study took place in Germany and involved a random sample of 1,923 adolescents and aged 14 to 24 years.

The researchers excluded anyone who reported cannabis use or pre-existing psychotic symptoms at the start of the study so that they could examine the relation between new (incident) cannabis use and psychotic symptoms.

The remaining participants were then assessed for cannabis use and psychotic symptoms at three time points over the study period (on average four years apart).

Incident cannabis use almost doubled the risk of later incident psychotic symptoms, even after accounting for factors such as age, sex, , use of other drugs, and other psychiatric diagnoses. Furthermore, in those with cannabis use at the start of the study, continued use of cannabis over the study period increased the risk of persistent psychotic symptoms

There was no evidence for self medication effects as psychotic symptoms did not predict later cannabis use.

These results "help to clarify the temporal association between cannabis use and psychotic experiences," say the authors. "In addition, cannabis use was confirmed as an environmental risk factor impacting on the risk of persistence of psychotic experiences."

The major challenge is to deter enough young people from using cannabis so that the prevalence of psychosis is reduced, say experts from Australia in an accompanying editorial.

Professor Wayne Hall from the University of Queensland and Professor Louisa Degenhardt from the Burnet Institute in Melbourne, question the UK's decision to retain criminal penalties for cannabis use, despite evidence that removing such penalties has little or no detectable effect on rates of use. They believe that an informed cannabis policy "should be based not only on the harms caused by use, but also on the harms caused by social policies that attempt to discourage its use, such as criminal penalties for possession and use."

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User comments : 8

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Burnerjack
4 / 5 (2) Mar 01, 2011
Reefer Madness! Its true! Ahhhhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!
Caliban
4 / 5 (3) Mar 02, 2011
For the one hundred trillionth time: Correllation does not equal causation!!!!!! Basic scientific methodology again ignored in( what one supposes is) deeply biased research.
alec123456789
1.7 / 5 (3) Mar 02, 2011
For the one hundred trillionth time: Correllation does not equal causation!!!!!! Basic scientific methodology again ignored in( what one supposes is) deeply biased research.


Calm down. The first paragraph acknowledged that they aren't sure if the correlation is casual of not. And they also acknowledged that any harms of cannabis use should be weighed against harms caused by social policies that attempt to discourage its use.

Every time there is an article about the effects of cannabis, all you potheads over-react like you think the scientific establishment is out to get you...
ormondotvos
5 / 5 (2) Mar 02, 2011
I wouldn't be worried if they were actual scientists, but they're social scientists...
Caliban
not rated yet Mar 02, 2011
Calm down. The first paragraph acknowledged that they aren't sure if the correlation is casual of not. And they also acknowledged that any harms of cannabis use should be weighed against harms caused by social policies that attempt to discourage its use.

Every time there is an article about the effects of cannabis, all you potheads over-react like you think the scientific establishment is out to get you...


You don't seem to understand.

Disclaiming the accuracy or even relevance of the results beforehand, doesn't excuse then trotting those same results out as -for all intents and purposes- bona fide.

You do see the difference? Good. Hash settled.
LivaN
not rated yet Mar 04, 2011
I have no doubt that cannabis use increases the risk of psychotic symptoms. Anyone who has used the substance will know how strong an effect it may cause to one's perceptions. Such an effect most certainly has the potential to negatively affect a developing mind, which is precisely what happens during adolescence (14 to 24 years). This is one of the reasons why we restrict the sale of harmful substances to minors.
That being said, I do believe the increase is far below what this article would have one assume. Actual numbers would have been nice rather than vague references like, almost doubled.
insignificant_fish
5 / 5 (1) Mar 05, 2011
Actual numbers would have been nice rather than vague references like, almost doubled.


Seriously! what are the general pop averages they are basing this on?

according to The Office of National Statistics, in the year 2000 in Great Britain, "One in 200 had a psychotic disorder such as psychosis and schizophrenia." So, if the numbers in the Netherlands are similar, 10 out of 1993 normal people, and 20 out of 1993 stoners.

What I want to know is if they have a control group of non smokers? Did they take into consideration the numbers of people that smoke that were polled to get the average stats?

This article is poorly written. I can only conclude that the British Medical Journal is not sifting what they print.

http://www.statis...?id=1333

Skeptic_Heretic
5 / 5 (4) Mar 05, 2011
Plant based cannabinoids are structurally similar to endocannabinoids which are found in all mammalian animals, including humans. As such they bind to the CB1 and CB2 receptors found throughout the nervous, immune, and musculature systems. THC operates in a bind mechanism with both receptors with approximately equal affinity.
Now, that being said, it has been established that in some human beings, genetic mutation results in reverse ion channels of various type, for example ADD and ADHD have been linked to the presence of a mutation that flips the polarity of hyperpolarization-activated cyclic nucleotide-gated channels. So when in the presence of this mutation, and when agonized by reception of a signal from the CB1 receptors to flood the channel, these individuals can suffer psychotic breaks, however, this is not a mutation found amongst people with no history of schizophrenia, bipolar disorder, or ADHD.

So in short, if pot drives you nuts, you were already nuts.