November 30, 2005

Brain Imaging - Cannabis and Schizophrenia Look Similar

It seems that every week brings new evidence of increased risks in developing schizophrenia if young adults use marijuana / cannabis:

Brain Scan Imaging shows similarities in brains of marijuana smokers, and people who have schizophrenia

Adolescents who regularly smoke marijuana risk damaging a key brain pathway associated with language development, and some predisposed to schizophrenia may contract the illness early, researchers said Wednesday, also at the meeting of the Radiological Society of North America.

These startling pictures show for the first time that the damage to the brain caused by smoking cannabis mimics that found in the brains of schizophrenia patients.

The images, taken using scanners, appear to prove that cannabis affects the brain's electrical signals in the same way as schizophrenia.

The U.S. research adds to a long list of studies which point to the drug as a trigger for the condition and a major factor in the development of mental illness in young people.

Lead researcher Dr Manzar Ashtari said: 'What we saw should cause alarm because the type of damage in cannabis smokers' brains was exactly the same as in those with schizophrenia and in exactly the same place in the brain.

'To me, this is proof of the damage cannabis can do.'

Professor Robin Murray, of the Institute of Psychiatry in London, said: 'This does seem to be a landmark study. For the first time, we are able to see the effects of cannabis smoking on the brain.'

Dr Ashtari's team, from New York's Albert Einstein School of Medicine in New York, used a new technique called diffusion sensor imaging to look deep into the brains of cannabis smokers, schizophrenia patients and healthy non-drug users.

Using a sophisticated brain imaging technique called diffusion tensor imaging (DTI), researchers at Zucker Hillside Hospital in Glen Oaks, New York, studied the brains of groups of adolescents: healthy, non-drug users; heavy marijuana smokers (daily use for at least one year); and schizophrenic patients. Unlike magnetic resonance imaging (MRI), which provides a static picture of brain structures, DTI detects and measures the motion of water molecules in the brain, which can reveal microscopic abnormalities.

Manzar Ashtari, Ph.D., Sanjiv Kumra, M.D., and colleagues used DTI to examine the arcuate fasciculus, a bundle of fibers connecting the Broca's area in the left frontal lobe and the Wernicke's area in the left temporal lobe of the brain. The investigators found that repeated exposure to marijuana was related to abnormalities in the development of this fiber pathway, which is associated with the higher aspects of language and auditory functions.

"Because this language/auditory pathway continues to develop during adolescence, it is most susceptible to the neurotoxins introduced into the body through marijuana use," explained Dr. Ashtari, associate professor of radiology and psychiatry at New York's Albert Einstein College of Medicine.

In the study, DTI was performed on 12 healthy, early adolescent males compared with 12 late adolescent males to show normal human brain development; 11 schizophrenic patients compared with 17 matched controls; 15 schizophrenic patients who smoke marijuana compared with 17 matched controls; and 15 marijuana smokers compared with 15 matched non-drug users. The scans revealed no abnormal developmental changes in the language pathway in the healthy adolescents, but showed abnormalities in both the marijuana users and schizophrenic patients.

"These findings suggest that in addition to interfering with normal brain development, heavy marijuana use in adolescents may also lead to an earlier onset of schizophrenia in individuals who are genetically predisposed to the disorder," said co-principal-investigator Sanjiv Kumra, M.D., assistant professor of psychiatry at Albert Einstein College of Medicine.

According to the National Institute on Drug Abuse, approximately 3.1 million Americans age 12 and older use marijuana on a daily or almost daily basis. In 2004, 5.6 percent of 12 th graders reported daily use of marijuana.

Schizophrenia is a chronic, severe and disabling brain disorder that affects about one percent of the entire population. Although the causes of the disease have not been determined, it is believed to result from a combination of environmental and genetic factors.

Drs. Ashtari and Kumra said longitudinal studies are needed to determine whether these changes in the brain are permanent or change over time. It is also important to mention that at this time, DTI and MRI are not diagnostic means for schizophrenia patients or marijuana smokers.

Read the more here: Drug disorder schizophrenia link

Source: Radiological Society of North America

More information on how Cannabis / Marijuana increases risk of schizophrenia


How can you be sure that marijuana is the only cause of the similar brain scan's?

It is said that marijuana is a gateway drug, how do we know that the people in these tests have only smoked marijuana.

Couldn't the similarities be from another drug as well?

I read about PCP being similar to the effects of Schizophrenia but what about the drug known as Acid.
How does that contribute?
Or Mescaline?

Posted by: Krysta at December 4, 2005 11:14 AM

If those people who smoke marajuana daily, stepstones to Schizophrenia then you could say that if those people drank milk, then Drinking Milk could stepstone to Schizophrenia also, logicaly speaking of course.

Posted by: Joseph Moldovan RT(R) at December 9, 2005 09:40 AM

Whow can we make a pattern of a normal brain, in order to compare to an abnormal one? People are so diferent.

Posted by: Venturi at December 11, 2005 07:40 PM

Not only is the test sample of this study worthlessly small, but the lack of proper background information and genetic/family history of the patients proves that this study's findings are presumptuous and factually ambiguous. It should be no surprise that a DRUG abnormally affects the human body. It should also be no surprise that the body, according to thousands of accredited studies, repairs itself completely after THC exposure at any level.

Posted by: Dan at December 13, 2005 10:05 AM

Hi! I think that another conclusion of these studies might be that schizophrenics are at an higher risk of cannabis use. The higher the risk of schizophrenia, the higher the risk of cannabis (and/or other drugs) use. I personnally find this hypothesis more likely than cannabis use promoting schizophrenia.

Posted by: Louis T. at December 19, 2005 12:59 PM

Louis T says it beautifully.

There is conclusive proof that cannabis does not cause schizophrenia. If cannabis caused schizophrenia, then the massive increase in cannabis use in countries like Australia since the 1960s would have been accompanied by a massive increase in schizophrenia. However, this did not happen. Despite an enormous cannabis plague over the past four decades, schizophrenia levels in Australia remained unchanged. Again, nowhere in the world has an increase in cannabis use led to an increase in schizophrenia, so the hypothesis that cannabis use causes schizophrenia can not be valid.

However, there is a definite correlation between schizophrenia and cannabis use. This can be partially explained because of shared factors (schizophrenia is more common in males as is cannabis use; the onset of schizophrenia is in the mid-20s; drug use is most common amongst the twenty-somethings etc). But these common factors alone seem insufficient.

So the explanation for the observed correlation may be that schizophrenia does cause cannabis use. It may be self-medication. It could be that people use drugs to relieve boredom and stress.


Dr Jiggens

Posted by: dr john jiggens at December 30, 2005 01:46 PM

Folks, I encourage you to review the following information from (an interview with Dr. Robin Murray:

SRF: Is cannabis use a large factor?

RM: Many American psychiatrists still regard cannabis consumption as safe, but it's become a very lively issue in Europe where most psychiatrists regard cannabis consumption as a cause of schizophrenia. However, the evidence is that it accounts for only a minority of schizophrenia. We found that if no one in New Zealand smoked cannabis, then the incidence of schizophrenia would decrease by about 8 percent; the comparable figures for Germany are 10 percent, and for Holland, 13 percent.

SRF: I would think that Americans vilify cannabis consumption more stridently than do Europeans. European governments have legalized or decriminalized its use. In America, that can't even be discussed, and the federal government recently petitioned the Supreme Court to overturn a law in Oregon allowing just its medicinal use, mainly as a painkiller.

RM: You are talking about policy makers and the general public. With psychiatrists, it's different. The reason why European psychiatrists are much more interested in cannabis use is precisely because people smoke more cannabis in Europe, and stronger varieties, than in the U.S.A. That's why we've seen more problems. If you'd asked me 15 years ago if cannabis causes schizophrenia, I would have said: "Of course not." But cannabis consumption in Europe has been escalating fast, whereas in America it has been fairly stable for about 25 years.

SRF: Do European psychiatrists want a tightening of the policies?

RM: There is a big dispute. In Britain, for example, the government didn't legalize cannabis, but made it less criminal. Here it's said that you only get arrested if you blow the smoke in a policeman's face. Our government made that change in 2002. Ironically, that was when the big new epidemiological studies started coming out. Personally, I don't think the legislation is that important. What matters is education. In Britain, now that the risks of cannabis consumption are becoming more widely known, there has been a dip in consumption, even though the legislation is now more liberal. It's probably more useful to educate people that there's a risk, rather than attempting to forbid it legally.

SRF: Is the effect of cannabis on risk strong enough that when you compare incidence rates in the States and Europe, where in the States, consumption of cannabis was stable and in Europe it's gone up, you can detect an increase in the incidence?

RM: I'm not aware of any competent large incidence study ever having been done in the U.S.A.

SRF: Why is the data from the U.S.A missing?

RM: Because you have a fragmented health system.

SRF: In Europe, has schizophrenia incidence gone up due to increased cannabis use?

RM: In Europe, there are good on-off epidemiological studies, but there's only one place that has data collected in the same way over decades. That's in South London, where I work. Here, the incidence of schizophrenia, as assessed by the same criteria from 1964 to 1999, has doubled (Boydell et al., 2003).

The reasons for that are complicated. One is because many more migrants live in London now, and migrants have higher rates of schizophrenia. But even if we look just at the native white population, rates went up, and our evidence is that drug abuse contributes to that. Nobody else has data collected in the same way consistently over decades, so it's difficult to make a broader assessment. We've discussed how difficult it is to define schizophrenia, and because of that you sometimes appear to see differences in incidence that are just due to differences in definition.

Posted by: szadmin at January 2, 2006 08:58 AM

im 17, heavy weed smoker, and recently diagnosed schizophrenic. i dunno if its coz of the weed, but i recommend dat any weed smokers should quit before you end up schizo like me. im still smokin it n its doing me no good im sure, but hey im already psycho so what does it f*ckin matter eh?!

Posted by: s at February 10, 2006 03:53 AM

Is there some kind of condition,that could be covered up with schizophrenia medication. That should be taken into consideration: Like some other kind of problems that can cause someone to look as though they have a condition of psychosis when they have some other underlying condition that has not been looked into?

Posted by: LP at March 9, 2006 07:29 PM

I'd like to say a couple things, first of all I'm 21 now and I've been experimenting with this topic myself for a year now.So, I can hear voices when I'm under the influence, the thing is, it's basicly your subconcious trying to argue with your conciousness while you in person are the listener. So what does this tell me, there isn't nothing wrong with it, who knows maybe its evolution. The thing that is funny about all of this, is that I speak 3 languages fluently and the voices talk to me in the language of the country that I'm currently living, why? Well thats because thats how I think at the moment. Also, I can even change the voices, ranging from men to woman and even children. What they say is all based on what I think and if I decide to counter their arguments thinking (not out loud) the voices may talk faster as if trying to overpower me, etc. It's basicly a child play with your imaginary friend, the older the get the more you believe god has something to do with it, or even that your god. In the end it all relates to one another. One more thing, body language plays a role in it too, since it itself is linked to paranoia.

Something I shouldn't say, but will anyway.. people can be affected about this indirectly, at least thats what I've noticed. Thats why I believe its evolution and I'm ahead in the game. Peace.

Anybody wanna scan my brain? We would get to a conclusion a lot faster.

Posted by: Rico at March 23, 2006 03:16 PM

Hope you are prepared to lose the linguistic knowlegde you've worked hard to learn, rico. Because you will. I speak from experience. As you grow and work into your 30s, you will be trying to stuff more knowledge into a space that is degrading faster than it should. Will you be schizo? Probably not. But cannabis DOES have a progressively accute effect on your brain. Physical. I don't need a scanner to know that.

Posted by: Anon at March 15, 2007 12:56 PM

rico you actually just said you are proud of being a nutcase. well done. does 'evolution' also invovle freeing all mass murderers because they are similarly 'enlightened'?

Posted by: notrico at March 19, 2007 04:31 AM

hey rico,

nice to know there's others like me. interested in how far you've gotten with it, but oh well...seems like i'm a year too late in responding. 5 years and going for me.

Posted by: pshh at April 30, 2007 07:02 PM

notrico, ur statement makes so many assumptions...

what makes you different from those mass murderers? u not being insane. i don't know if you have had the pleasure of hearing voices or not, but know that the path the experience opens depends solely on your own choices and ur ability to maintain ur sense of reasoning. you can hear negatives voices, but it's ur choice to follow. as for me, my relation with 'negative voices' was shortlived as i found my path out through questioning. i could go on and on but in the end, it all boils down to your faith. not necessarily associating with religion but i guess it can help some ppl. the only thing anybody has to remember: the experiences you have, regardless of the journeys you take and the path you choose, remember to keep it to yourself. never ever associate anybody else with it. it's the inability of weak minded ppl that can't realize it is a personal experience that cause them to kill people and claim "the voices told me so". fools.

Posted by: pshh at May 2, 2007 12:50 AM

It's not only the brain marajuana smokers have to worry about, but also their lungs. Lung cancer will probably kill them before their brain does!

As a reformed pot smoker, drawing from my experience I believe the following; When you (and your mind) are trapped inside the pot world you cannot see out into the real world, but when/if you get out, only then can you see your world AND the pathetic pot world and realise how insecure and mixed up pot users are. I know three pot users who are severe schizophrenics now and on strong medication, making their eyeballs go in different directions. So to anyone who is out there who still smokes the stuff, you cannot see what you are doing until you are clean and free from the stuff for at least one year. I believe once paranoia sets in with pot smoking, then those paranoid thoughts can mark the beginning of schizophrenia. I am not a doctor or a scientist but just going on my instinct and what I've witnessed througout my life's experiences. Life just gets better once you stop.

How did I get onto this website anyway? P:)

Posted by: Penelope at June 23, 2007 01:08 AM

Schizophrenia is no joke, I don't think it relates to any drug effect.

Posted by: Giada De Laurentiis at March 31, 2008 01:24 AM

Some Questions regarding the interview with Dr. Robin Murray.

RM: “We found that if no one in New Zealand smoked cannabis, then the incidence of schizophrenia would decrease by about 8 percent; the comparable figures for Germany are 10 percent, and for Holland, 13 percent.”

As a researcher my question is: How could you possibly prove such a statement? Did Dr. Robin Murray go to Earth 2 (which is exactly similar to Earth 1 except that the genus cannabis does not exist) and measure their schizophrenia levels?

RM: “The reason why European psychiatrists are much more interested in cannabis use is precisely because people smoke more cannabis in Europe, and stronger varieties, than in the U.S.A. That's why we've seen more problems.”

Question 1: I have looked at the cannabis seizures from the UN and noted that over 50% of the cannabis seized comes from North America. South America, Asia and Africa have larger cannabis seizures than Europe. The only continents Europe beats in cannabis seizures are Australia and Antarctica. What evidence does RM have for the claim that people smoke more cannabis in Europe than America?

Question 2: What evidence is that that European varieties are stronger than American varieties? Surely similar strains are available everywhere via seeds purchased over the internet?

Posted by: Dr John Jiggens at June 9, 2008 12:56 AM

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