Kannabiksen käytön ja skitsofrenian yhteys mutkikas

Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Kyllästynyt » 30.06.2014 09:29

Kannabiksen käytön ja skitsofrenian yhteys mutkikas

Viesti Lähetetty 28.06.2014 15:49 Kirjoittaja Psykopatologia

"Kannabiksen ja skitsofrenian yhteys luultua mutkikkaampi"
Kuka luulee, kuka ei.

------------------------

"Yhteisten alttiusgeenien vaikutus ei ole suuri,"
Vaikka luvut ovat tilastollisesti merkitseviä, olennaista on efektin suuruus, joka on siis vähäinen.
------------------------

Yritin jakaa ketjua, mutta töpeksin ja ketju hajosi.
Yllä oleva teksti on siis Psykopatologian kirjoittama, jonka jouduin töpeksintäni takia kopiomaan palstalle uudelleen.

Pahoittelen sotkua.
Kyllästynyt
 

Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 12:18

Voisitko laittaa uudelleen aloitusviestissä olleen artikkelin, jonka otsikon jätit komeilemaan pilalle menneeseen ketjuun? Trissen laittama artikkeli on poistettu, joten se ainokainen viesti, jonka kopioit talteen, on mitäänsanomaton.

Harmittaa sen artikkelin poistaminen, sitä ei päästä lukemaan muualta.

Tässä linkki menetettyyn artikkeliin:
http://suomenkuvalehti.fi/jutut/tiede/k ... kikkaampi/
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Mirri
 
Viestit: 21979
Liittynyt: 01.01.2012 19:18

Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Kyllästynyt » 30.06.2014 13:10

Mirri kirjoitti:Voisitko laittaa uudelleen aloitusviestissä olleen artikkelin, jonka otsikon jätit komeilemaan pilalle menneeseen ketjuun? Trissen laittama artikkeli on poistettu, joten se ainokainen viesti, jonka kopioit talteen, on mitäänsanomaton.

Harmittaa sen artikkelin poistaminen, sitä ei päästä lukemaan muualta.

Tässä linkki menetettyyn artikkeliin:
http://suomenkuvalehti.fi/jutut/tiede/k ... kikkaampi/

Valitettavasti en saa kyseistä artikkelia avattua.

Yritän vielä keksiä jotain...

Lisäys klo 13:34

Olisiko näistä apua?

http://www.theverge.com/2014/6/24/58367 ... cated-than

The link between weed and schizophrenia is way more complicated than we thought

Study finds genetic overlap between cannabis use and schizophrenia
By Arielle Duhaime-Ross on June 24, 2014 04:00 am Email @ArielleDRoss

The association between marijuana and schizophrenia is historically fraught. In the 1960s and 1970s, scientists thought that smoking weed could trigger psychosis in just about anyone. Today, these findings are more nuanced, but researchers still think that cannabis can trigger schizophrenia in people who are predisposed to the disease — meaning those with family histories of the disorder. Yet, in the last decade, some scientists have actually started to look at the effect in reverse. The resulting studies suggest that the neurobiology underlying schizophrenia might also put people affected by the disorder at increased risk for smoking pot. But these results haven't garnered nearly as much attention as studies suggesting the opposite.

PART OF THE ASSOCIATION MIGHT BE CAUSED BY GENETIC OVERLAP

Now, a new study, published today in Molecular Psychiatry, lends further support to the idea that schizophrenia plays a role in an individual's likelihood of smoking weed, by showing that the genetic variants predicting schizophrenia can also be used to predict a person's tendency to smoke pot, regardless of their mental health history. This, researchers say, demonstrates that the causal relationship between cannabis use and schizophrenia might not be clear-cut, and that at least a small part of the association might be caused by genetic overlap, where the same genes that predispose certain people to enjoying weed might also predispose others to developing schizophrenia — or both.

To tease apart this relationship, researchers took genetic data from recently published studies of schizophrenia, and identified genetic variants associated with the disease. Then, they applied that information to a random sample of about 2,000 healthy Australians to see if those variants could also predict cannabis use.

"MORE LIKELY TO USE CANNABIS, AND IN GREATER QUANTITIES."

"There is a well-established link between people who use cannabis and schizophrenia," says Robert Power, lead author of the study and a genetic psychiatrist at King's College London. But this study indicates "that people who are at risk for schizophrenia are more likely to use cannabis, and in greater quantities," he says — which means the causal relationship might actually go both ways. Moreover, the genetic variants associated with schizophrenia were predictive for cannabis use in healthy individuals, so there appears to be some genetic overlap between the two.

"These findings are very valuable," says Eden Evins, a psychiatry professor at Harvard University who was not involved in the study, "and suggest that increased genetic risk for schizophrenia increases the chance that someone will use cannabis, and use it heavily." But Evins doesn't think these results rule out previous findings that cannabis use increases a person's risk for developing schizophrenia. "Both may be true," she says. This sentiment was echoed by Wolfram Kawohl, a psychiatrist at the University of Zurich, who said the results show that "the connection is more complicated than some people may have thought," and that "both connections may exist parallel along with possible others."

"I AM SUSPECT THAT THIS FINDING WILL HOLD OUT WITH THE TEST OF TIME."

But Lynn DeLisi, another Harvard University psychiatry professor, isn't convinced. "I am suspect that this finding will hold out with the test of time," she told The Verge in an email. DeLisi points to her own work, which showed there was no difference in family history of schizophrenia between people who smoke weed and people who don't. So, although there might be an interaction between smoking weed and schizophrenia, DeLisi said, it would be need to be shown in "studies of people using cannabis compared with those who don't, both having a family history of schizophrenia."

Furthermore, DeLisi thinks that today's high rates of cannabis use among teenagers and adults make it hard to link drug use to mental health issues or their genetic predispositions. "Everyone uses cannabis these days, and I don't think they necessarily have genetic predispositions to do so."

AN ONGOING DEBATE
"The relationship is an ongoing debate in the scientific world — at least what the nature of the association is," said Matthew Hill, a cell biologist at the University of Calgary in Canada, who recently published an article dissecting this very relationship, in an email to The Verge. In the article, Hill argued that "there is little evidence that, at a population level, cannabis use during adolescence is a primary contributing factor in the development of psychiatric illness." But he also noted that "there is evidence that in high-risk populations, cannabis can be highly adverse, so arguments claiming that cannabis is innocuous are equally flawed."

WEED AFFECTS PEOPLE WITH SCHIZOPHRENIA DIFFERENTLY

When The Verge asked about the risks associated with cannabis use, Hill said that "there are detailed studies which have demonstrated that cannabis can have very different effects on the brain of someone who is at risk for schizophrenia than someone who isn't." One 2013 study, for instance, demonstrated that the increased release of dopamine from smoking marijuana is amplified in the brains of people with schizophrenia, as well as in their close relatives. The results of this amplification are poorly understood, but some scientists think that a chronic elevation of dopamine can increase one's likelihood of experiencing psychotic episodes, and make the disorder harder to treat. Moreover, some studies indicate that people who find themselves in the early stages of schizophrenia and who also smoke weed experience larger brain modifications — such as changes in their white matter — compared to those who don't.

"CANNABIS USE WORSENS THE COURSE OF SCHIZOPHRENIA."

"There is definitely some kind of genetic basis to increased vulnerability to these adverse effects [in people with schizophrenia] that go beyond the correlational association discussed in this paper," Hill says. Evins agreed. "It's well known that cannabis use worsens the course of schizophrenia," she said, "so people with schizophrenia should be discouraged from using it."

Furthermore, some studies have found that smoking pot accelerates the development of schizophrenia in those who are genetically predisposed, but that association took a hit in 2010, when researchers found that accounting for things like gender, lifetime mental health history, and socioeconomic status erased the effect. Still, some studies continue to point to this risk.

Perhaps the reasons for these contradictory findings is that some individuals with schizophrenia react more strongly to marijuana than others with the same disorder. This was the finding of one 2010 study that demonstrated that 44 out of 121 schizophrenic participants either developed schizophrenia within a month of beginning to smoke marijuana, or saw their psychosis amplified by drug use.

A COMPLICATED RELATIONSHIP
Given all of this conflicting evidence, it seems likely that the relationship between marijuana and schizophrenia is even more complex than we once thought. No single gene has been associated with either drug addiction or schizophrenia, so these illnesses are the result of many genes working in combination, Evins said, "each with a small contribution to the overall risk of developing the disorders." There's also a plethora of environmental factors that need to be taken into account — most of which we barely understand.

THIS "DOESN'T GET A LOT OF ATTENTION."

Still, Hill said, the idea that cannabis use and schizophrenia share common genes "is interesting," partly because it highlights a dimension of this relationship that doesn't get a lot of attention. But causality is never easy to confirm, so this study will need to be replicated multiple times. And even then, Kawohl said, researchers probably won't be able to say that "cannabis use has no consequences for the risk to develop schizophrenia."

Regardless, it's important to remember that schizophrenia only affects a small number of people — about 1 percent of the US adult population — so "the vast majority of adolescents and young adults who use cannabis won't develop it," Evins said. And that's actually a crucial point, because despite all the studies that link schizophrenia and cannabis, few have been able to explain why schizophrenia rates have remained stable — and may actually be declining — in the face of pot's increasing popularity among teens.

THE ECONOMIC BENEFIT OF LIMITING POT USE IS "PRETTY SMALL."

"There may still be a causal role between cannabis and schizophrenia, but our results suggest that this causal role may have been overestimated," Power says. This is important, he says, because some people have used cannabis' relationship with psychosis to argue against its legalization. "Already the actual economic benefit of limiting cannabis use in terms of schizophrenia is pretty small," Power says, pointing to a study that found that policymakers would have to stop at least 3,000 adolescents from smoking weed to prevent one case of psychosis from emerging.

Still, Power thinks people with a family history of schizophrenia should avoid weed. "The clinical advice is to stay away from events that might have a potential to cause stress," he says, because genes and environment are interconnected. Thus, "people who are at-risk should try to avoid things that might damage their mental well-being." These things, he says, include weed.

------------------------------------------------------------------------------------
http://content.time.com/time/health/art ... 59,00.html
The Link Between Marijuana and Schizophrenia
By Maia Szalavitz Wednesday, July 21, 2010

Since the days of Reefer Madness, scientists have sought to understand the complex connection between marijuana and psychosis. Cannabis can cause short-term psychotic experiences, such as hallucinations and paranoia, even in healthy people, but researchers have also long noted a link between marijuana use and the chronic psychotic disorder, schizophrenia.

Repeatedly, studies have found that people with schizophrenia are about twice as likely to smoke pot as those who are unaffected. Conversely, data suggest that those who smoke cannabis are twice as likely to develop schizophrenia as nonsmokers. One widely publicized 2007 review of the research even concluded that trying marijuana just once was associated with a 40% increase in risk of schizophrenia and other psychotic disorders.

But here's the conundrum: while marijuana went from being a secret shared by a small community of hepcats and beatniks in the 1940s and '50s to a rite of passage for some 70% of youth by the turn of the century, rates of schizophrenia in the U.S. have remained flat, or possibly declined. For as long as it has been tracked, schizophrenia has been found to affect about 1% of the population.

One explanation may be that the two factors are coincidental, not causal: perhaps people who have a genetic susceptibility to schizophrenia also happen to especially enjoy marijuana. Still, some studies suggest that smoking pot can actually trigger the disease earlier in individuals who are predisposed, and yet researchers still aren't seeing increases in the overall schizophrenia rate or decreases in the average age of onset.

In recent months, new research has explored some of these issues. One study led by Dr. Serge Sevy, an associate professor of psychiatry at the Albert Einstein College of Medicine in New York City, looked at 100 patients between the ages of 16 and 40 with schizophrenia, half of whom smoked marijuana. Sevy and colleagues found that among the marijuana users, 75% had begun smoking before the onset of schizophrenia and that their disease appeared about two years earlier than in those who did not use the drug. But when the researchers controlled for other factors known to influence schizophrenia risk, including gender, education and socioeconomic status, the association between disease onset and marijuana disappeared.

Gender alone accounted for a large proportion of the risk of early onset in Sevy's study, which included 69 men and 31 women. "Males in general have earlier age of onset of schizophrenia," says Sevy. In men, the disease tends to take hold around age 19, while in women it isn't typically seen until 22 — irrespective of marijuana use. But, typically, teenage boys are four times more likely than girls to be heavy pot smokers, which may create an illusory association between the drug and onset of the disease.

Yet past studies limited to males have found exactly such a link, associating marijuana use with earlier development of full-blown psychosis. And other research has found that ongoing cannabis use increases hospitalizations for psychotic symptoms in schizophrenic patients and decreases social and cognitive functioning. A 2008 review of the data found that relapse and failure to take prescribed medication was consistently associated with cannabis use, although, again, controlling for other factors weakened the link.

One explanation could be that the effects of marijuana vary depending on the genetics of the individual patient's schizophrenia. Marie-Odile Krebs, professor of psychiatry at the National Institute of Health and Medical Research (INSERM) laboratory in France, and her colleagues published a study in June that identified two broad groups of people with schizophrenia who used cannabis: those whose disease was profoundly affected by their drug use and those who were not.

Within Krebs's study population of 190 patients (121 of whom had used cannabis), researchers found a subgroup of 44 whose disease was powerfully affected by the drug. These patients either developed schizophrenia within a month of beginning to smoke pot or saw their existing psychosis severely exacerbated with each successive exposure to the drug. Schizophrenia appeared in these patients nearly three years earlier than in other marijuana-users with the disease.

The key difference between the cannabis-sensitive patients and the nonaffected group was a family history of disease: those in the former group had three times the number of close relatives with psychotic disorders, says Krebs. Further, the sensitive group started smoking pot at a younger age — before age 17, compared with 18 in patients without marijuana sensitivity — and Krebs thinks the early exposure may have critically altered the development of brain receptors affected by marijuana.

These receptors, known as endocannabinoid receptors, affect the action of the brain's dopamine systems, fine-tuning the response of the neurons involved. Although this process is not yet completely understood, changing the way endocannabinoids influence dopamine during development could result in a chronically high level of dopamine in some regions of the brain, which may increase the likelihood of psychotic episodes. Stimulant drugs such as amphetamine and cocaine, which increase the action of the dopamine system, for instance, are known to produce psychotic experiences, while antipsychotic drugs work by blocking the brain's dopamine receptors.

Given that an estimated 50% of the risk for schizophrenia is attributable to genes and family history, disseminating the results of research like Krebs's could help delay the onset of disease in thousands of people and prevent years of severe disability in those with a family history of schizophrenia. Although the disease itself affects only 1% of the population, about 10% of healthy people have personality features that, when intensified, may characterize schizophrenia — such as paranoia — meaning that the proportion of the population who may be sensitive to marijuana could be larger than expected, Krebs says.

However, discouraging marijuana use in patients who have schizophrenia or are at high risk of developing it is a complicated task, not least because the drug is extremely popular with this group. Their affinity for the drug may be related to a phenomenon recently described in a study published in the British Journal of Psychiatry: The research tracked the moods of 80 marijuana smokers, 42 of whom had psychotic disorders like schizophrenia. Participants were asked to record their moods at various points over the course of six days, determined by a watch that beeped periodically to signal the volunteers. All participants, not surprisingly, reported feeling happier when they were high, but the mood-lifting effect of marijuana was stronger among smokers with schizophrenia. Unlike people without the disease, schizophrenia patients also reported a reduction in negative feelings after smoking marijuana. "Everyone feels better," explains lead author Cecile Henquet, an assistant professor of psychology and psychiatry at Maastricht University in Holland. "But [schizophrenia] patients also have less anxiety and are less socially withdrawn."

But which is the chicken and which is the egg? In another study by Sevy at Albert Einstein College of Medicine, researchers interviewed adults with schizophrenia (and their families) who smoked marijuana, and found that they reported being better adjusted during childhood than those who did not indulge. It makes sense when you consider the practicalities and social nature of drug use. Being at least somewhat socially connected is necessary to be able to obtain an illegal drug — if you appear too "crazy," people are less likely to befriend you and dealers may be too wary to sell to you. Many people with schizophrenia exhibit odd behavior that puts them at risk for social rejection years before they develop full-blown delusions and hallucinations in adulthood.

The access issue may also help explain why some studies find better — not worse — cognitive functioning in people with schizophrenia who smoke marijuana. That's what Pamela DeRosse, a research scientist at Long Island's Feinstein Institute for Medical Research, and her colleagues found in a study of 455 people with schizophrenia published in Schizophrenia Research in July. The research showed that patients who smoked marijuana had faster brain processing speed, greater verbal ability and better memory than patients who didn't smoke — not attributes usually associated with being high. "I can't really tell you why they aren't doing worse," says DeRosse. "But in order to go out to even find cannabis, enough to become dependent or abuse it, requires that you be more cognitively intact than the average patient with schizophrenia."

Indeed, many schizophrenia patients who smoke pot smoke enough to become addicted. As Henquet's study showed, the drug's mood-boosting effects appear immediately after smoking, as do some hallucinations, but the bulk of negative marijuana-related effects appear later on, as an increased rate of hallucination that affects patients even when they are not high. This is the exact type of drug effect that raises addiction risk: The user's experience is one of short-term gain associated with the drug, with long-term pain that seems unrelated. "This is what explains why patients with schizophrenia use cannabis for longer and more frequently than controls," says Henquet. "They are apparently more sensitive to the addictive potential than other people."

That marijuana can have such incompatible effects in schizophrenia patients — enhancing mood while exacerbating hallucinations and delusions — is not surprising, when its chemical makeup is considered. One chemical called delta-9 tetrahydocannabinol (THC) is known to cause hallucinations and in high doses can even make healthy people feel paranoid or suffer brief attacks of psychosis. But another component of marijuana called cannabidiol (CBD) has anti-psychotic effects.

Consequently, researchers who study the knotty relationship between drug use and schizophrenia hope that patients may one day benefit from cannabis-derived drugs. The key is to replicate the antipsychotic properties of CBD without triggering the risks carried by THC. But in the meantime, scientists are still trying to identify which patients, based on genes and family history, may be most helped by potential new pharmaceutical drugs and who may be spared harm by avoiding illicit drug use now.
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 13:46

Avatar
Psykopatologia
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Viestit: 57805
Liittynyt: 12.02.2010 13:19
Paikkakunta: Helsinki

Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 14:51

Kyllästynyt kirjoitti:
Mirri kirjoitti:Voisitko laittaa uudelleen aloitusviestissä olleen artikkelin, jonka otsikon jätit komeilemaan pilalle menneeseen ketjuun? Trissen laittama artikkeli on poistettu, joten se ainokainen viesti, jonka kopioit talteen, on mitäänsanomaton.

Harmittaa sen artikkelin poistaminen, sitä ei päästä lukemaan muualta.

Tässä linkki menetettyyn artikkeliin:
http://suomenkuvalehti.fi/jutut/tiede/k ... kikkaampi/

Valitettavasti en saa kyseistä artikkelia avattua.

Yritän vielä keksiä jotain...

Lisäys klo 13:34

Olisiko näistä apua?

http://www.theverge.com/2014/6/24/58367 ... cated-than

The link between weed and schizophrenia is way more complicated than we thought

Study finds genetic overlap between cannabis use and schizophrenia
By Arielle Duhaime-Ross on June 24, 2014 04:00 am Email @ArielleDRoss

The association between marijuana and schizophrenia is historically fraught. In the 1960s and 1970s, scientists thought that smoking weed could trigger psychosis in just about anyone. Today, these findings are more nuanced, but researchers still think that cannabis can trigger schizophrenia in people who are predisposed to the disease — meaning those with family histories of the disorder. Yet, in the last decade, some scientists have actually started to look at the effect in reverse. The resulting studies suggest that the neurobiology underlying schizophrenia might also put people affected by the disorder at increased risk for smoking pot. But these results haven't garnered nearly as much attention as studies suggesting the opposite.

PART OF THE ASSOCIATION MIGHT BE CAUSED BY GENETIC OVERLAP

Now, a new study, published today in Molecular Psychiatry, lends further support to the idea that schizophrenia plays a role in an individual's likelihood of smoking weed, by showing that the genetic variants predicting schizophrenia can also be used to predict a person's tendency to smoke pot, regardless of their mental health history. This, researchers say, demonstrates that the causal relationship between cannabis use and schizophrenia might not be clear-cut, and that at least a small part of the association might be caused by genetic overlap, where the same genes that predispose certain people to enjoying weed might also predispose others to developing schizophrenia — or both.

To tease apart this relationship, researchers took genetic data from recently published studies of schizophrenia, and identified genetic variants associated with the disease. Then, they applied that information to a random sample of about 2,000 healthy Australians to see if those variants could also predict cannabis use.

"MORE LIKELY TO USE CANNABIS, AND IN GREATER QUANTITIES."

"There is a well-established link between people who use cannabis and schizophrenia," says Robert Power, lead author of the study and a genetic psychiatrist at King's College London. But this study indicates "that people who are at risk for schizophrenia are more likely to use cannabis, and in greater quantities," he says — which means the causal relationship might actually go both ways. Moreover, the genetic variants associated with schizophrenia were predictive for cannabis use in healthy individuals, so there appears to be some genetic overlap between the two.

"These findings are very valuable," says Eden Evins, a psychiatry professor at Harvard University who was not involved in the study, "and suggest that increased genetic risk for schizophrenia increases the chance that someone will use cannabis, and use it heavily." But Evins doesn't think these results rule out previous findings that cannabis use increases a person's risk for developing schizophrenia. "Both may be true," she says. This sentiment was echoed by Wolfram Kawohl, a psychiatrist at the University of Zurich, who said the results show that "the connection is more complicated than some people may have thought," and that "both connections may exist parallel along with possible others."

"I AM SUSPECT THAT THIS FINDING WILL HOLD OUT WITH THE TEST OF TIME."

But Lynn DeLisi, another Harvard University psychiatry professor, isn't convinced. "I am suspect that this finding will hold out with the test of time," she told The Verge in an email. DeLisi points to her own work, which showed there was no difference in family history of schizophrenia between people who smoke weed and people who don't. So, although there might be an interaction between smoking weed and schizophrenia, DeLisi said, it would be need to be shown in "studies of people using cannabis compared with those who don't, both having a family history of schizophrenia."

Furthermore, DeLisi thinks that today's high rates of cannabis use among teenagers and adults make it hard to link drug use to mental health issues or their genetic predispositions. "Everyone uses cannabis these days, and I don't think they necessarily have genetic predispositions to do so."

AN ONGOING DEBATE
"The relationship is an ongoing debate in the scientific world — at least what the nature of the association is," said Matthew Hill, a cell biologist at the University of Calgary in Canada, who recently published an article dissecting this very relationship, in an email to The Verge. In the article, Hill argued that "there is little evidence that, at a population level, cannabis use during adolescence is a primary contributing factor in the development of psychiatric illness." But he also noted that "there is evidence that in high-risk populations, cannabis can be highly adverse, so arguments claiming that cannabis is innocuous are equally flawed."

WEED AFFECTS PEOPLE WITH SCHIZOPHRENIA DIFFERENTLY

When The Verge asked about the risks associated with cannabis use, Hill said that "there are detailed studies which have demonstrated that cannabis can have very different effects on the brain of someone who is at risk for schizophrenia than someone who isn't." One 2013 study, for instance, demonstrated that the increased release of dopamine from smoking marijuana is amplified in the brains of people with schizophrenia, as well as in their close relatives. The results of this amplification are poorly understood, but some scientists think that a chronic elevation of dopamine can increase one's likelihood of experiencing psychotic episodes, and make the disorder harder to treat. Moreover, some studies indicate that people who find themselves in the early stages of schizophrenia and who also smoke weed experience larger brain modifications — such as changes in their white matter — compared to those who don't.

"CANNABIS USE WORSENS THE COURSE OF SCHIZOPHRENIA."

"There is definitely some kind of genetic basis to increased vulnerability to these adverse effects [in people with schizophrenia] that go beyond the correlational association discussed in this paper," Hill says. Evins agreed. "It's well known that cannabis use worsens the course of schizophrenia," she said, "so people with schizophrenia should be discouraged from using it."

Furthermore, some studies have found that smoking pot accelerates the development of schizophrenia in those who are genetically predisposed, but that association took a hit in 2010, when researchers found that accounting for things like gender, lifetime mental health history, and socioeconomic status erased the effect. Still, some studies continue to point to this risk.

Perhaps the reasons for these contradictory findings is that some individuals with schizophrenia react more strongly to marijuana than others with the same disorder. This was the finding of one 2010 study that demonstrated that 44 out of 121 schizophrenic participants either developed schizophrenia within a month of beginning to smoke marijuana, or saw their psychosis amplified by drug use.

A COMPLICATED RELATIONSHIP
Given all of this conflicting evidence, it seems likely that the relationship between marijuana and schizophrenia is even more complex than we once thought. No single gene has been associated with either drug addiction or schizophrenia, so these illnesses are the result of many genes working in combination, Evins said, "each with a small contribution to the overall risk of developing the disorders." There's also a plethora of environmental factors that need to be taken into account — most of which we barely understand.

THIS "DOESN'T GET A LOT OF ATTENTION."

Still, Hill said, the idea that cannabis use and schizophrenia share common genes "is interesting," partly because it highlights a dimension of this relationship that doesn't get a lot of attention. But causality is never easy to confirm, so this study will need to be replicated multiple times. And even then, Kawohl said, researchers probably won't be able to say that "cannabis use has no consequences for the risk to develop schizophrenia."

Regardless, it's important to remember that schizophrenia only affects a small number of people — about 1 percent of the US adult population — so "the vast majority of adolescents and young adults who use cannabis won't develop it," Evins said. And that's actually a crucial point, because despite all the studies that link schizophrenia and cannabis, few have been able to explain why schizophrenia rates have remained stable — and may actually be declining — in the face of pot's increasing popularity among teens.

THE ECONOMIC BENEFIT OF LIMITING POT USE IS "PRETTY SMALL."

"There may still be a causal role between cannabis and schizophrenia, but our results suggest that this causal role may have been overestimated," Power says. This is important, he says, because some people have used cannabis' relationship with psychosis to argue against its legalization. "Already the actual economic benefit of limiting cannabis use in terms of schizophrenia is pretty small," Power says, pointing to a study that found that policymakers would have to stop at least 3,000 adolescents from smoking weed to prevent one case of psychosis from emerging.

Still, Power thinks people with a family history of schizophrenia should avoid weed. "The clinical advice is to stay away from events that might have a potential to cause stress," he says, because genes and environment are interconnected. Thus, "people who are at-risk should try to avoid things that might damage their mental well-being." These things, he says, include weed.

------------------------------------------------------------------------------------
http://content.time.com/time/health/art ... 59,00.html
The Link Between Marijuana and Schizophrenia
By Maia Szalavitz Wednesday, July 21, 2010

Since the days of Reefer Madness, scientists have sought to understand the complex connection between marijuana and psychosis. Cannabis can cause short-term psychotic experiences, such as hallucinations and paranoia, even in healthy people, but researchers have also long noted a link between marijuana use and the chronic psychotic disorder, schizophrenia.

Repeatedly, studies have found that people with schizophrenia are about twice as likely to smoke pot as those who are unaffected. Conversely, data suggest that those who smoke cannabis are twice as likely to develop schizophrenia as nonsmokers. One widely publicized 2007 review of the research even concluded that trying marijuana just once was associated with a 40% increase in risk of schizophrenia and other psychotic disorders.

But here's the conundrum: while marijuana went from being a secret shared by a small community of hepcats and beatniks in the 1940s and '50s to a rite of passage for some 70% of youth by the turn of the century, rates of schizophrenia in the U.S. have remained flat, or possibly declined. For as long as it has been tracked, schizophrenia has been found to affect about 1% of the population.

One explanation may be that the two factors are coincidental, not causal: perhaps people who have a genetic susceptibility to schizophrenia also happen to especially enjoy marijuana. Still, some studies suggest that smoking pot can actually trigger the disease earlier in individuals who are predisposed, and yet researchers still aren't seeing increases in the overall schizophrenia rate or decreases in the average age of onset.

In recent months, new research has explored some of these issues. One study led by Dr. Serge Sevy, an associate professor of psychiatry at the Albert Einstein College of Medicine in New York City, looked at 100 patients between the ages of 16 and 40 with schizophrenia, half of whom smoked marijuana. Sevy and colleagues found that among the marijuana users, 75% had begun smoking before the onset of schizophrenia and that their disease appeared about two years earlier than in those who did not use the drug. But when the researchers controlled for other factors known to influence schizophrenia risk, including gender, education and socioeconomic status, the association between disease onset and marijuana disappeared.

Gender alone accounted for a large proportion of the risk of early onset in Sevy's study, which included 69 men and 31 women. "Males in general have earlier age of onset of schizophrenia," says Sevy. In men, the disease tends to take hold around age 19, while in women it isn't typically seen until 22 — irrespective of marijuana use. But, typically, teenage boys are four times more likely than girls to be heavy pot smokers, which may create an illusory association between the drug and onset of the disease.

Yet past studies limited to males have found exactly such a link, associating marijuana use with earlier development of full-blown psychosis. And other research has found that ongoing cannabis use increases hospitalizations for psychotic symptoms in schizophrenic patients and decreases social and cognitive functioning. A 2008 review of the data found that relapse and failure to take prescribed medication was consistently associated with cannabis use, although, again, controlling for other factors weakened the link.

One explanation could be that the effects of marijuana vary depending on the genetics of the individual patient's schizophrenia. Marie-Odile Krebs, professor of psychiatry at the National Institute of Health and Medical Research (INSERM) laboratory in France, and her colleagues published a study in June that identified two broad groups of people with schizophrenia who used cannabis: those whose disease was profoundly affected by their drug use and those who were not.

Within Krebs's study population of 190 patients (121 of whom had used cannabis), researchers found a subgroup of 44 whose disease was powerfully affected by the drug. These patients either developed schizophrenia within a month of beginning to smoke pot or saw their existing psychosis severely exacerbated with each successive exposure to the drug. Schizophrenia appeared in these patients nearly three years earlier than in other marijuana-users with the disease.

The key difference between the cannabis-sensitive patients and the nonaffected group was a family history of disease: those in the former group had three times the number of close relatives with psychotic disorders, says Krebs. Further, the sensitive group started smoking pot at a younger age — before age 17, compared with 18 in patients without marijuana sensitivity — and Krebs thinks the early exposure may have critically altered the development of brain receptors affected by marijuana.

These receptors, known as endocannabinoid receptors, affect the action of the brain's dopamine systems, fine-tuning the response of the neurons involved. Although this process is not yet completely understood, changing the way endocannabinoids influence dopamine during development could result in a chronically high level of dopamine in some regions of the brain, which may increase the likelihood of psychotic episodes. Stimulant drugs such as amphetamine and cocaine, which increase the action of the dopamine system, for instance, are known to produce psychotic experiences, while antipsychotic drugs work by blocking the brain's dopamine receptors.

Given that an estimated 50% of the risk for schizophrenia is attributable to genes and family history, disseminating the results of research like Krebs's could help delay the onset of disease in thousands of people and prevent years of severe disability in those with a family history of schizophrenia. Although the disease itself affects only 1% of the population, about 10% of healthy people have personality features that, when intensified, may characterize schizophrenia — such as paranoia — meaning that the proportion of the population who may be sensitive to marijuana could be larger than expected, Krebs says.

However, discouraging marijuana use in patients who have schizophrenia or are at high risk of developing it is a complicated task, not least because the drug is extremely popular with this group. Their affinity for the drug may be related to a phenomenon recently described in a study published in the British Journal of Psychiatry: The research tracked the moods of 80 marijuana smokers, 42 of whom had psychotic disorders like schizophrenia. Participants were asked to record their moods at various points over the course of six days, determined by a watch that beeped periodically to signal the volunteers. All participants, not surprisingly, reported feeling happier when they were high, but the mood-lifting effect of marijuana was stronger among smokers with schizophrenia. Unlike people without the disease, schizophrenia patients also reported a reduction in negative feelings after smoking marijuana. "Everyone feels better," explains lead author Cecile Henquet, an assistant professor of psychology and psychiatry at Maastricht University in Holland. "But [schizophrenia] patients also have less anxiety and are less socially withdrawn."

But which is the chicken and which is the egg? In another study by Sevy at Albert Einstein College of Medicine, researchers interviewed adults with schizophrenia (and their families) who smoked marijuana, and found that they reported being better adjusted during childhood than those who did not indulge. It makes sense when you consider the practicalities and social nature of drug use. Being at least somewhat socially connected is necessary to be able to obtain an illegal drug — if you appear too "crazy," people are less likely to befriend you and dealers may be too wary to sell to you. Many people with schizophrenia exhibit odd behavior that puts them at risk for social rejection years before they develop full-blown delusions and hallucinations in adulthood.

The access issue may also help explain why some studies find better — not worse — cognitive functioning in people with schizophrenia who smoke marijuana. That's what Pamela DeRosse, a research scientist at Long Island's Feinstein Institute for Medical Research, and her colleagues found in a study of 455 people with schizophrenia published in Schizophrenia Research in July. The research showed that patients who smoked marijuana had faster brain processing speed, greater verbal ability and better memory than patients who didn't smoke — not attributes usually associated with being high. "I can't really tell you why they aren't doing worse," says DeRosse. "But in order to go out to even find cannabis, enough to become dependent or abuse it, requires that you be more cognitively intact than the average patient with schizophrenia."

Indeed, many schizophrenia patients who smoke pot smoke enough to become addicted. As Henquet's study showed, the drug's mood-boosting effects appear immediately after smoking, as do some hallucinations, but the bulk of negative marijuana-related effects appear later on, as an increased rate of hallucination that affects patients even when they are not high. This is the exact type of drug effect that raises addiction risk: The user's experience is one of short-term gain associated with the drug, with long-term pain that seems unrelated. "This is what explains why patients with schizophrenia use cannabis for longer and more frequently than controls," says Henquet. "They are apparently more sensitive to the addictive potential than other people."

That marijuana can have such incompatible effects in schizophrenia patients — enhancing mood while exacerbating hallucinations and delusions — is not surprising, when its chemical makeup is considered. One chemical called delta-9 tetrahydocannabinol (THC) is known to cause hallucinations and in high doses can even make healthy people feel paranoid or suffer brief attacks of psychosis. But another component of marijuana called cannabidiol (CBD) has anti-psychotic effects.

Consequently, researchers who study the knotty relationship between drug use and schizophrenia hope that patients may one day benefit from cannabis-derived drugs. The key is to replicate the antipsychotic properties of CBD without triggering the risks carried by THC. But in the meantime, scientists are still trying to identify which patients, based on genes and family history, may be most helped by potential new pharmaceutical drugs and who may be spared harm by avoiding illicit drug use now.

Muuten hyvä, mutta kieli on väärä suomenkieliselle foorumille; pitäisi olla suomennos.

Hoidan homman itse, niin saan mieleiseni.
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 14:54

Kannabiksen ja skitsofrenian yhteys luultua mutkikkaampi
Tutkijoiden mukaan kannabiksen käytön ja skitsofrenian välinen yhteys saattaa selittyä geeneillä.

Suomen Kuvalehti
Marko Hamilo
27.6.2014 18:38|Päivitetty 27.6.2014 18:58

Viime vuosisadan jälkipuoliskolla kannabiksesta tuli yleisimmin käytetty laiton päihde. On yleisesti tunnettua, että kannabiksen käyttö on paljon yleisempää skitsofreniaan sairastuneiden keskuudessa kuin muussa väestössä.

Pitkittäistutkimukset viittaavat siihen, että kannabiksen käyttö kaksinkertaistaa skitsofrenian puhkeamisen riskin. Mitä enemmän kannabista on käyttänyt, sitä suurempi skitsofreniaan sairastumisen riski. Tutkimukset eivät kuitenkaan pysty vahvistamaan syyn ja seurauksen suuntaa.

Joissakin pienillä aineistolla tehdyissä tutkimuksissa on jopa saatu viitteitä siitä, että psykoosi on kannabiksen käytön riskitekijä. Tätä voisi selittää se, että skitsofreniaan sairastuneet lääkitsisivät oireitaan kannabiksella.

Yhteyden saattaa selittää myös ainakin osaksi se, että samat geenit altistavat sekä skitsofrenialle että kannabiksen käytölle. Tähän viittaa Molecular Psychiatry -lehdessä julkaistu uusi tutkimus.

Lontoon King’s Collegen tutkija Robert Power löysi yhteyden 2082 terveellä yksilöllä skitsofreniariskiä lisäävien geenien ja kannabiksen käytön välillä. Aineistona oli australialainen kaksosrekisteri. Sekä skitsofrenian että kannabiksen käytön tiedetään periytyvän osin geneettisesti. Aiemmissa tutkimuksissa on löydetty skitsofrenialle altistavia geenialueita. Kannabiksen käytölle altistavia geenejä ei ole tunnistettu.

Geneettinen vaikutus näkyi sekä siinä, oliko yksilö koskaan kokeillut kannabista vai ei, että kannabista kokeilleiden joukossa käytön määrässä. Molemmat yhteydet olivat tilastollisesti merkitseviä.

Tutkijoiden mukaan heidän tuloksensa osoittavat, että kannabiksen käytön ja skitsofrenian välinen yhteys selittyy ainakin jossakin määrin geeneillä, jotka altistavat molempiin. Toisin sanoen niillä yksilöillä, joilla on muuta väestöä suurempi geneettinen alttius sairastua skitsofreniaan, on myös muuta väestöä suurempi geneettinen alttius kokeilla kannabista ja käyttää sitä suuria määriä.

Yhteisten alttiusgeenien vaikutus ei ole suuri, mutta se on samaa suuruusluokkaa kuin aiemmissa tutkimuksissa havaittu yhteys, joka on tulkittu kannabiksen käytön skitsofreniaa lisääväksi vaikutukseksi.

Powerin mukaan tutkimus ei kuitenkaan sulje pois vaihtoehtoa, että myös kannabis voi olla skitsofrenian itsenäinen riskitekijä.

Aiemmin on esitetty arvioita, että yhden skitsofreniatapauksen ehkäisemiseksi kannabiksen käyttäjien määrän pitäisi vähentyä tuhansilla yksilöillä. Tämä on perustunut oletukseen, jonka mukaan yhteys kannabiksen ja skitsofrenian välillä olisi yksisuuntainen syy-yhteys.

Uusi tutkimus kuitenkin avaa mahdollisuuden, että yhteys olisi monimutkaisempi ja aiemmat arviot kannabiksen käytön terveysriskeistä liioiteltuja.

http://suomenkuvalehti.fi/jutut/tiede/k ... d94e7461-4
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Mirri
 
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 14:55

Mitä järkeä kopioida uudestaan? - Jos ei aiemmin ole käynyt SK:n sivuilla, ko. teksti aukeaa.
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 15:21

Mitä järkeä yrittää säilyttää tämä ketju otsikoineen, jos siinä ei ole mukana aloitusviestiä - ydinasiaa. Juuri tuo tänne takaisin laittamani artikkeli oli ketjun ydin; ei kai sentään ollut tarkoitus sensuroida sitä pois ketjusta.
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Mirri
 
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 16:18

Kiitos, Mirri!
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 21:37

Eipä kestä! Sitähän minäkin, että se alkuperäinen ja keskustelun synnyttänyt artikkeli kuuluu tämän otsikon alle. :)
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Mirri
 
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 21:54

Psykopatologia kirjoitti:Mitä järkeä kopioida uudestaan? - Jos ei aiemmin ole käynyt SK:n sivuilla, ko. teksti aukeaa.

Mitä järkeä kopioda Kyllästyneen pitkä viesti ja kirjoittaa sen jälkeen pari lausetta.
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 22:00

En ole lainannut väärin.
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 22:13

Psykopatologia kirjoitti:Mitä järkeä kopioda Kyllästyneen pitkä viesti ja kirjoittaa sen jälkeen pari lausetta.

Ei mitään järkeä. Mutta en jaksanut ryhtyä miettimään miten ilmaisisin sanottavani ilman kopiointia, joten menin helpoimman kautta.

Kyllästyneen viestin pituus johtui sen sisältämistä englanninkielisistä pitkistä siteerauksista. Miten olisin voinut viitata niihin lyhyesti ja ytimekkäästi - ja lisäksi lukijoiden kannalta ymmärrettävästi - kopioimatta niitä? En keksinyt vastausta tuohon kysymykseen, joten kopioin.
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Mirri
 
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 22:19

Kyllästynyt kirjoitti:
Mirri kirjoitti:Voisitko laittaa uudelleen aloitusviestissä olleen artikkelin, jonka otsikon jätit komeilemaan pilalle menneeseen ketjuun? Trissen laittama artikkeli on poistettu, joten se ainokainen viesti, jonka kopioit talteen, on mitäänsanomaton.

Harmittaa sen artikkelin poistaminen, sitä ei päästä lukemaan muualta.

Tässä linkki menetettyyn artikkeliin:
http://suomenkuvalehti.fi/jutut/tiede/k ... kikkaampi/

Valitettavasti en saa kyseistä artikkelia avattua.

Yritän vielä keksiä jotain...

Lisäys klo 13:34

Olisiko näistä apua?

Muuten hyvä, mutta kieli on väärä suomenkieliselle foorumille; pitäisi olla suomennos.

Hoidan homman itse, niin saan mieleiseni.

(Yritin uudelleen ja jätin pitkät vieraskieliset siteeraukset pois viestistä.)
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Mirri
 
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Kyllästynyt » 30.06.2014 22:30

trisse kirjoitti:Mirri on monesti sanonut ettei osaa englantia... kuvittelisi Kyllästyneenkin tietävän.

Tiesin, mutten muistanut.

Eikä kyse ollut vain Mirristä, kai joku muukin tätä ketjua lukee.
Kyllästynyt
 

Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 22:57

Kyse oli siitä, että toiskertalaiset eivät voineet kopioda SK:n kirjoitusta.
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Kyllästynyt » 30.06.2014 23:18

trisse kirjoitti:Ja ensiluokkainen unohti Mirrin kielitaidon (vaikka koulutus lienee terävästi muistissa).

En unohtanut siinä mielessä, etten olisi asiaa (Mirrin kielitaidottomuutta) muistanut; unohdin vain (sillä kyseisellä hetkellä) ottaa asia huomioon.
Kyllästynyt
 

Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 23:19

23:18
Alun perin oli kyse siitä, että trisse sotki (taas) ketjua omilla älyttömyyksillään.
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Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Mirri » 30.06.2014 23:19

Kyllästynyt kirjoitti:
trisse kirjoitti:Mirri on monesti sanonut ettei osaa englantia... kuvittelisi Kyllästyneenkin tietävän.

Tiesin, mutten muistanut.

Eikä kyse ollut vain Mirristä, kai joku muukin tätä ketjua lukee.

Minä kaipailin aloitusviestissä ollutta Suomen Kuvalehden suomenkielistä kirjoitusta takaisin tähän ketjuun. Niinpä laittamasi vieraskieliset tekstit olivat outo vastaus pyyntööni. Silti, vaikka nekin ilmeisesti olivat luettavissa alkuperäisessä ketjussa; taisivat olla alunalkaen Psykopatologian tänne lainaamia.
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Mirri
 
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Liittynyt: 01.01.2012 19:18

Re: Kannabiksen käytön ja skitsofrenian yhteys mutkikas

ViestiKirjoittaja Psykopatologia » 30.06.2014 23:22

Ei se mikään outo vastaus ollut, vaan mahdoton eräiden toteuttaa.
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