25 year study concluded: smoking marijuana doubles risk of getting schizophrenia

[jay gw]

Smoking cannabis virtually doubles the risk of developing mental illnesses such as schizophrenia, researchers say.

The New Zealand scientists said their study suggested this was probably due to chemical changes in the brain which resulted from smoking the drug.

The study, published in the journal Addiction, followed over 1,000 people born in 1977 for 25 years.

UK mental health campaigners said it was more evidence of a "drug-induced mental health crisis".

The researchers, from the University of Otago, interviewed people taking part in the Christchurch Health and Development Study about their cannabis use at the ages of 18, 21 and 25.

They were also interviewed about various aspects of their mental health.

The scientists found psychotic symptoms were more common among cannabis users.

They analysed their findings to take into account of the possibility that their illness encouraged people to use more cannabis, rather than the drug contributing to their condition.

But the researchers said the link was not likely to be due to people with mental illness having a greater wish to smoke cannabis.

Instead, they said cannabis may increase the chances of a person suffering psychosis by causing chemical changes to the brain.

"These findings add to the growing body of evidence from different sources, all of which suggest that heavy use of cannabis may lead to increased risk of psychotic symptoms and disease in susceptible individuals."

http://news.bbc.co.uk/2/hi/health/4305783.stm

Smoking cigarettes and drinking alcohol both cause problems too. So does eating fast food like McDonalds. Everything causes some bad side effects.

Is that enough reason to keep marijuana illegal?

[Eos of the Eons]

Considering how the drug can be used to self treat, then it might be said that those with problems are more likely to use it. I would be skeptical of the claim that it could cause schizophrenia.

They analysed their findings to take into account of the possibility that their illness encouraged people to use more cannabis, rather than the drug contributing to their condition.


"These findings add to the growing body of evidence from different sources, all of which suggest that heavy use of cannabis may lead to increased risk of psychotic symptoms and disease in susceptible individuals."






Have to go see if they cited sources for the second quote. Don't have much time...interesting topic.

[UnrepentantSinner]

Gee, a psychotropic substance might/can cause a psychosis?

No F-ing way!

[Rob Lister]

Call me skeptical but there are more variables than those presumably accounted for. Perhaps those that are willing to experiment with pot have personalities that make them more open to honestly answering probing questions regarding their mental state. Perhaps the experimentation opens up an awarness of the mental state that others who have not experimented do not possess. Perhaps the findings are agenda driven.

[edthedoc]

The same rules apply to the use of any recreational drug:

There are those that use, and those that don't.
There are those who use but shouldn't, and those that don't but should.

;)

[davefoc]

Unfortunately the BBC article linked to was almost useless as a source of information.

My first question was how common schizophrenia was in the general population. If the rate is around two cases per thousand and the study found four cases per thousand in their particular sample of marijuana users I wouldn't see that as all that statistically significant a result.

Secondly, the article offers no clue as to the frequency of marijuana use that leads to increased mental disorders.

Thirdly the artile doesn't indicate what types of mental illnesses are doubled with marijuana use it just says "mental illnesses such as schizophrenia". I realize this is just an article for the general public but this one struck me as so vague that it was useless.

I did a search on Fergusson and marijuana to see if I couldn't find a little more info on the researcher or the study that the article was about. Fergusson is a professor at ChristChurch in Australia. He seems to be involved in doing studies on the effects of marijuana use and the studies that I found any information on seemed to have results that suggested problems with marijuana.

I found this FAQ from a site on using marijuana as medicine.
http://www.acmed.org/english/faq/27-psychosis.htm

From this site:
Conclusions: The available epidemiologic evidence supports the following conclusions: 1) that cannabis use and psychosis are associated in clinical and general population samples; 2) the association is unlikely to be due to common causes or other confounding factors; 3) the time trends in schizophrenia and cannabis use are not consistent with hypothesis that cannabis use causes new schizophrenia; 4) in contrast, it is likely that cannabis use precipitates disorders in vulnerable individuals and exacerbates symptoms of psychosis in those who continue to use cannabis; 5) persons with schizophrenia and other psychoses may be more likely to become regular users if they use cannabis; and 6) emerging evidence on the role of the cannabinoid system in psychotic symptoms is consistent with the epidemiologic evidence that cannabis use can precipitate and exacerbate psychosis.

Bottom line: marijuana use doesn't cause psychosis but it can " precipitate and exacerbate" it in a vulnerable person.

One statistic they cite in support of this view is that despite rising marijuana use in Australia there has not been a corresponding increase in the rate of schizophenia.

Even though, IMHO, marijuana use amongst adults should be legal I think it is a dangerous practice and I suspect that there are problems with routine use. Unfortunately it seems to me that there is a move to spin the results of any studies that find problems with marijuana use into unrealistic reports about how bad the drug is. This seems to be one of those things where the agenda of the people involved often outweighs any notions about the importance of truth.

[Jas]

I know that smoking marijuana can trigger a psychotic episode, though I didn't think that it would actually cause the illness itself.

My mom used to be a nurse at a psychiatric hospital. A large proportion of the people in there had mental illnesses that were triggered by their drug use. The majority were habitual users, but there was a significant number who just had a bad reaction, and were now in the hospital, probably for the rest of their lives.

[Charlie Monoxide]

The voices in my head aren't letting me respond to this thread appropriately ....

Charlie (refer madness) Monoxide

[Eos of the Eons]

Originally posted by davefoc
Unfortunately the BBC article linked to was almost useless as a source of information.

My first question was how common schizophrenia was in the general population. If the rate is around two cases per thousand and the study found four cases per thousand in their particular sample of marijuana users I wouldn't see that as all that statistically significant a result.

Secondly, the article offers no clue as to the frequency of marijuana use that leads to increased mental disorders.

Thirdly the artile doesn't indicate what types of mental illnesses are doubled with marijuana use it just says "mental illnesses such as schizophrenia". I realize this is just an article for the general public but this one struck me as so vague that it was useless.

I did a search on Fergusson and marijuana to see if I couldn't find a little more info on the researcher or the study that the article was about. Fergusson is a professor at ChristChurch in Australia. He seems to be involved in doing studies on the effects of marijuana use and the studies that I found any information on seemed to have results that suggested problems with marijuana.



Thanks Dave. There are one out of a hundred people in the Wordly population that has schizophrenia. It doesn't matter what nationality you are either.The Prevalance Rate for schizophrenia is approximately 1.1% of the population over the age of 18

Schizophrenia occurs in all societies at about the same rate, regardless of class, colour, religion, culture.


http://www.schizophrenia.com/szfacts.htm

[Zep]

Originally posted by davefoc
I did a search on Fergusson and marijuana to see if I couldn't find a little more info on the researcher or the study that the article was about. Fergusson is a professor at ChristChurch in Australia. He seems to be involved in doing studies on the effects of marijuana use and the studies that I found any information on seemed to have results that suggested problems with marijuana. In view of the original study location, wouldn't that more likely be the city of Christchurch in New Zealand? I don't think NZ is a state of Australia...yet! :)

[Jon_in_london]

The dutch experience shows an overall drop in the level of cannabis use post-legalisation. So yes it should be legal. Also, its immoral to lock someone up with murderers and rapists for the hideous crime of smoking a spliff.

As to it causing mental illness..... define mental illness.

[davefoc]

Zep said: In view of the original study location, wouldn't that more likely be the city of Christchurch in New Zealand?

Do you mean that Austrailia and New Zealand are two different places? You all sound alike to me.