Dylan points the core taboo, but Deleuze and Gattari go further by focusing on schizophrenia as not only an effect of capitalism, but its very cause. Denying what Bergson called "Creative Imagination" as the main human dynamic leads to a social paradigma that reduces human beings to normalized consummers.

Ethnologically, the fact is that Marihuana is closely tied to western spirituality, specially through monotheist prophetism.

Psychically, Marihuana is to be taken as a powerful substance that induces differents ways to understand reality. Taking MH is somewhat as much stimulating than stopping it - depending of what is called "altered consciousness".

Marihuana is assimilated by human body as Anandamine, neurotransmetter of happiness ("ananda" in sanskrit), trhough "cannabinoïds receptors" which are present in the entire nervous system . Stopping it leads to a certain sadness, oftenly haunted by disturbing dreams or "visions".

Schizophrénia ? - Spirit Life, folks !

Lion de Juda, Paris, France

I don't care for it one bit. I don't smoke pot. I do however study psychology and neurology.
This research comes out, and all of a sudden everyone is freaking out, and saying it is a reason to keep the drugs illegal.
That's ridicuous.
First. The two studies showed a correlation between marijuana use and psychosis. This is not the same as "Marijuana causes psychosis". Has it ever occured to you that people with a proprensity for insanity are more likely to smoke pot?

(That being said I do not doubt that some increase in risk is obtained from smoking pot. Flooding your brain with cannibinoids regularly is likey to have some undesirable effects)

The second thing to point out... Alcohol is also linked to psycholsis! So this political posturing that THC is somehow special is beyond belief.

Shea Kauffman, Seattle, Wa

Having smoked marijuana for the past 36 years and still very very sane, I conclude that the "psychosis" comes from the chemicals used to grow the drug, rather than from the drug itself. I won't smoke anything chemically grown and I'm not psychotic.

Michelle, Bowral,

The fact that cannabis may or may not increase the risk of psychosis is irrelevant to the reclassification from B to C, in that possession is now a non-arrestable offence. What do our erstwhile doctors and politicians suggest, that we jail the mentally ill? The argument for reclassification makes no sense as it is still an offence to possess and dealers still face stiff penalties.Anyone dumb enough to think it changed anything is a fool, and anyone who thinks the reclassification is sending out the wrong message is an even greater fool, and assumes a great deal of ignorance on the part of the population at large. Whether or not it increases the risk of psychosis, people should be left to make there own informed choice. Reclassify it to A if you want, it wont stop people taking it, and it certainly wont stop the hypocrisy that is still prevalant in out so-called civilised society.

Doug, Glasgow, Scotland

THis is a much more complex issue than it at first seems I notice there was no headlines when a study in may showed another chemical component to cannabis, cannabidinol (CBD), actually inhibits and suppresses psychotic symptoms in people suffering from them. CBD is so good at suppressing psychotic symptoms that it proved to be more effective than any of the major anti-psychotics currently prescribed by doctors.

Professor Jim van Os suggests a solution: legal cannabis could be easily grown and marketed with high CBD levels, ending the psychotic effect. Indeed, such a drug would actually be helpful for psychotics to smoke. Obviously, it's impossible to do this while cannabis remains in the hands of organised crime syndicates - a certainty under prohibition. So it is actually more accurate to say cannabis prohibition causes cannabis psychosis, and legalisation would end it.

John Leeson, Sheffield, UK

there is a book called 'capitalism and schizophrenia' by Deleuze and Guattari. it can demonstrate that capitalism itself is the cause of going schizo.

The point being that studies, studies and studies are all able to be spun however those with power and access to the media want to spin them. its not about reclassifying cannabis its about providing information for people to make informed decisions. Skunk I think isnt good for anyone, but by making weed illegal people have no choice anyway. So stiffer penalities isnt going to fix anything.

Dylan, London,

It may be that our civilian police enjoy an occasional toke, not just our international political murderers. Here in the USA, drugs are responsible for much of our prison population. Well, drug laws are responsible. And privatization of prisons make them a profitable business. More business is better business. Sigh. Relax, smiling is absurd. Just pay your taxes and stay drunk. It is the only socially responsible choice. If you would rather not drink, pay your taxes and shut your mouth. Or else! And Saddam was a tyrant ... sure, whatever you say ;)

Alan Marcy, Phoenix, USA/Arizona

But is it the other way round, that people who are predisposed to psychosis are more inclined to smoke canabis heavily?

This needs a longitudinal study following a large group of people over a period, starting before any of them is old enough to have smoked, otherwise you can't tell the egg from the chicken.

Nigel Robertson, Melton Mowbray,

Its true that pot makes people more introspective, but it is through the eyes of our alcohol swigging society that introspection is perceived as a negative. If people were to think for themselves and disregard the herd/consumer mentality that has taken over the western world, then the soulless system of exploitative economics that we have so saturated ourselves in might very well change.

Also, alcohol and cigarettes have killed more people than Adolf Hitler ever did, which is somehow acceptable, whereas a mild drug that promotes creativity and emotional well-being is shunned. Who is it that has trouble arguing rationally?

Pass me that doobie...

Sir Smoke-A-Lot, Arcata, California

"The Lancet paper gives irrefutable evidence that there is an obvious and proven association between cannabis smoking and psychotic breakdown."

This statement is the article is a pure and blatant lie, as the Lancet article says nothing of the sort,
The interpretation of the statement of research in the Lancet reads:
http://www.thelancet.com/journals/lancet/article/PIIS0140673604162004/abstract?pubType=related

"Interpretation

Available evidence does not strongly support an important causal relation between cannabis use by young people and psychosocial harm, but cannot exclude the possibility that such a relation exists. The lack of evidence of robust causal relations prevents the attribution of public health detriments to illicit drug use. In view of the extent of illicit drug use, better evidence is needed."

Basically no irrefutable evidence nor obvious or proven associasion!

Please keep your facts straight.

Atli, Reading, England

What this version of the story does not mention is that, according to medical writer Maria Cheng from the Associated Press, "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." I think that explains it all.

Dave Miller, Santa Cruz, CA,

Cannabis should be legalised. In a free and liberal society people have to be allowed to make their own choices providing they aren't directly harming anyone else. Millions of people use cannabis in the UK, criminalising them won't help one bit. Every study done seems to rank alcohol as more harmful than cannabis, but I don't hear people screaming for a return to prohibition.

Drugs laws are driven by moralistic hysteria, they're a joke and most young people don't even take them seriously.

If the Labour Party reclassify cannabis as a class C drug it will be a gift for the Lib Dems

David, Aberdeen, Scotland

Of course there is no conclusive proof that cannabis causes psychosis, we don't have it for tobacco and lung cancer either, but we accept the link.
Boydell and others in 2003 found that the incidence of schizophrenia had doubled between 1965 and 1997, with the greatest increase among the under 35s.
There is other evidence apart from numbers. Cannabis increases the amount of the neurotransmitter dopamine in the brain.
Schizophrenics have an excess of this substance. In 2005 Caspi and others discovered a rogue gene (COMT), carried by 25% of us, for the transmission of dopamine. If a child inherits 2 copies of this gene and uses cannabis the risk of developing psychosis rises from 1 to3%, the norm, to 15%. In the same year, Ashtari et al, looking at brain scans, found abnormalities in the brains of non-cannabis using adolescent schizophrenics similar to those of daily cannabis-using adolescents.
Use in boys aged 11 to 12 is still rising. Immature brains are most at risk.

Mary Brett, Amersham, UK

Let's get some perspective on this. People need information, and young people should know that it is unwise to smoke it in early to mid teenage years. It really is best to wait, and thus reduce your chances of psychological damage. And even then, of course it is sensible to exercise moderation, as with all of life's little pleasures. But this does not justify draconian laws, which would criminalise so many of us.

I quote Bruce Spring, MD, an assistant professor of clinical psychiatry at the University of Southern California Keck School of Medicine, Los Angeles, an expert familiar with the study but not involved in it.

"It certainly gives cause for concern,"

Still, he says, the overall risk is relatively low, statistically speaking.

"In general, the overall risk of someone getting a psychotic illness is about 3%," he says. "Now what this study is saying is that that 3% risk is increased by 40% [or more]," he says. So the risk with marijuana use would rise to 4.2%.

Steve Lowman, Aberystwyth, Wales

"Many believe that in young people it has a disastrous effect on academic performance, motivation, judgment, ability to argue rationally and can leave cannabis takers abnormally and excessively introspective"

Err, no. What it does is giving meaningful insight into the fact that we live in a souless, materially obsessed, emotionally retarded society that stamps out the sensitive, tender, empathatic aspects of humanity.

This realisation naturally creates a desire to withdraw from all that which is crass and meaningless. Users of charas feel in their heart and soul what most of society tries to bury and ignore - that our ignorance and greed is leading us towards self destruction.

Charas is a valuable tool for spiritual engagement and emtional literacy. Unfortunately, our society is very sick and the pain of this realisation leads many to self medicate to an extect that they are rendered numb to their feelings. Hey, let's make them criminals as well? That will help.

Mike Ford, Morecambe,

so how does the statistical evidence hold up to examination when it is noted that , despite the enormous increase in cannabis use in the last 30-odd years (and the prevalence of skunk for 15), the incidence of schizophrenia and psychosis has remained static?
Dr Stuttafford, your first paragraph outlines the axe - the rest of your article sounds like grinding and cant.

micky2shoes, Reading, Berks

Too much alcohol will kill you.
Too many cigarettes will kill you.
Overeating may kill you.
Stress may kill you.
This report contains nothing new and in many ways it is merely the application of common sense.
Whilst I am 100% against the use of hard drugs, it has already been determined that cannabis is less harmful than either tobacco or alcohol. In fact there has never been a documented fatality due entirely to the use of cannabis.
Most alcoholics have mental problems and "second-hand" tobacco smoke has been shown to affect persons other than smokers.
For goodness sake lets get these arguments into perspective.
Many, many young people are being treated in hospital every
week due to the effects of alcohol poisoning while smokers put a huge strain on our health service.
I'm in my late 50s and I know many people who still enjoy a "spliff " maybe once or twice a month. Most of these folk neither drink to excess or smoke cigarettes.
Too much of anything is bad for you...Simple.

Jeffers, Maidstone,

Thomas, as a doctor you should know better than to confuse correlation and causation. The reasons for taking drugs are multifarious and often have distinct psycho-social implications. That someone takes a drug such as cannabis in the first place, let alone becomes reliant on it, is the outcome of a diversity of social and psychological pressures.

To say that this "meta-analysis" offers proof is disingenuous, particularly as two of the more in depth studies are based on service personnel. Cannabis users in the armed forces are likely to be marginalised and exposed to a variety of factors (and other drugs) that non-users in the forces will not experience.

That drugs are ubiquitous within the armed forces ensures that access is universal. Nowhere is there unambiguous evidence that the people who become dependent on (any) drugs do not differ significantly in propensity to depression or potentially addictive behaviour, which may well correlate with unexpressed or latent psychosis

Kidd Garrett, Bristol, UK