Marijuana Use Increases Psychosis Risk
Posted by Warm Southern Breeze on Wednesday, March 9, 2011
Marijuana Use Increases Psychosis Risk
Well folks, here it is again. Yet more studies that conclusively demonstrate that SMOKING MARIJUANA IS BAD FOR YOU!!
Regular readers of my blog will have already read the other numerous scientific studies about which I have previously written.
Here are two more studies – one involving 20,000 people with psychotic illness, and another involving 1,923 people ages 14-24 over a period of 10 years.
Dutch researchers led by Jim van Os from Maastricht University conducted the decade-long youth study in Germany and ruled out those that presently smoked marijuana and those with pre-existing psychosis. They found that new marijuana use doubled the risk of new psychotic symptoms, even after accounting for age, sex, socio-economic status, other drug use and other psychiatric disorders.
Dr Matthew Large, from Australia’s University of New South Wale’s School of Psychiatry and Prince of Wales Hospital worked in partnership with Melbourne, Australia’s St. Vincent’s Hospital and the U.S.’s George Washington University School of Medicine and Health Sciences, pooled patient data from more than 80 studies which had probed the link between psychotic illness and substance abuse. Previous studies had examined the role of marijuana, alcohol and other psychoactive substances, but this new study examined marijuana alone. They found that most of the schizophrenic patients had been marijuana smokers, and of those who had been, the onset of mental illness occurred 2.7 years earlier.
Addendum: 5/5/14 – The reader should note that the majority of all such research upon the long-term, or delayed effects of marijuana usage has been focused upon the immature (and therefore, not-fully-developed) brain. Most researchers have concluded that the human brain reaches full maturity around age 25. The greatest risks for psychoses in later life is experienced when the immature brain is exposed to cannabis.
Smoking pot may hasten onset of mental illness
By Nancy Lapid Nancy Lapid – Mon Feb 7, 5:19 pm ET
NEW YORK (Reuters Health) – Smoking marijuana has been linked with an increased risk of mental illness, and now researchers say that when pot smokers do become mentally ill, the disease starts earlier than it would if they didn’t smoke pot.
This means that serious psychiatric diseases that might not have shown up until kids were in their teens or twenties – or might never had developed at all – are starting in children as young as 12 who smoke marijuana.
The link between using pot and developing serious mental illness is strongest in the youngest smokers – 12- to 15-year-olds, or kids even younger, said Dr. Matthew Large in an interview with Reuters Health.
“We have to (tell) people who have marijuana in their pockets not to give it to younger people,” said Large, who headed up the research at the University of New South Wales in Sydney, Australia.
Large and his colleagues looked at thousands of patients with psychotic disorders like schizophrenia. People with psychotic disorders lose touch with reality — usually starting in adolescence or young adulthood.
The authors of the new study found that in the subjects who had been pot smokers, the psychotic symptoms began nearly 3 years earlier than in those who had not been marijuana users.
People with schizophrenia often have hallucinations (they see things that aren’t there) and delusions (they’re often convinced something improbable is true, when it isn’t); they also tend to have unusual or bizarre behavior, social problems, and general difficulty in coping with life. According to the National Institute of Mental Health, approximately 2.4 million American adults, or about one in every 100 people over age 18, have schizophrenia.
The vast majority of young people who use marijuana don’t develop psychosis. And so far, no one’s been able to prove that smoking marijuana actually causes psychotic disorders like schizophrenia, but the new research adds to “growing evidence” that it does, at least in some people, said Dr. Michael T. Compton at George Washington University Medical Center in Washington, DC, who worked on the study.
A number of studies had already suggested that people develop schizophrenia at a younger age if they’ve been using pot – even if they weren’t heavy users — but not all researchers agreed.
To get a better sense of the evidence, Large and Compton and their colleagues systematically combined and analyzed data from 83 studies involving more than 22,000 people with psychotic disorders like schizophrenia: 8,167 who used marijuana or other substances, and 14,352 who did not.
“Those who used marijuana had an earlier age at onset of the disorder, by (about 32 months) on average, than those who had not used marijuana,” Compton said in e-mail to Reuters Health.
Why was there disagreement in the past over whether this effect really exists? The reasons lie in the way the individual studies might have been done, the researchers say in their article, published in the Archives of General Psychiatry.
In their larger analysis, they made sure to account for several factors that authors of the individual studies might not have considered. For example, psychosis develops earlier in boys than in girls – but Large and Compton found that even when they adjusted for that difference, the pot smokers still developed psychotic symptoms earlier.
Also, older people are less likely to be smoking pot than younger patients, so if the individual studies had different proportions of various age groups, the results might have been skewed. Taking that factor into account, the researchers still found that marijuana users developed mental illness at a younger age.
They also tried to see whether their findings could be explained by the year the research was done (because pot may have become more potent over time), whether the research had been done according to good scientific principles, and whether the investigators had defined the start of mental illness according to the date it was diagnosed instead of the date the symptoms started (the date symptoms started is more accurate). But they kept coming back to the same result: people with psychotic disorders who smoked marijuana had symptoms of mental illness at a younger age than those who didn’t use pot.
The researchers did not look at whether family history of psychosis played a role in determining who was most vulnerable to marijuana’s apparent early-triggering effect.
Are there some kids who are more at risk of psychosis from smoking pot than others? “I’m sure there are,” Large said. Kids with a family history of psychosis, or those with some psychotic symptoms but not full-blown schizophrenia are at particular risk, he said. But also at risk are kids who are struggling, not doing well at school or living in bad situations at home.
One study found that compared to people who didn’t use marijuana, people over 18 who did use it had twice the risk of mental illness, but kids under 15 had five times the risk, Large said.
There are two main messages to take away from this work, Large said. One is that there’s probably something in marijuana that triggers schizophrenia. What that is, isn’t clear yet. “Schizophrenia is still a mystery,” he said. “Psychotic illnesses are horrible for the people who have them, and terrible for their families too.”
The second message is far more important, he believes. Public health campaigns on the dangers of marijuana are focusing on older users, Large said, and overlooking the pre-teens and young adolescents who get their pot from older peers and even older siblings at home.
“Even if the onset of psychosis were inevitable (for a particular individual),” Large’s team writes, “an extra 2 or 3 years of psychosis-free functioning could allow many patients to achieve the important developmental milestones” of adolescence. That extra time could allow a young person to finish school and gain other skills that might reduce the lifelong disability that so often accompanies mental illnesses.
Whereas most studies like his are presented at medical conferences, Large said he’s not going to bother traveling around to announce his results to other doctors. Instead, he said, he wants to talk about his results in public forums.
“I’m not a marketing expert,” he said, “but we have to find a way to tell young kids to hold off.” We might not be able to convince them to never use pot, he added, but they need to wait until they’re older – a message, he acknowledged, that will be tricky to deliver.
SOURCE: http://bit.ly/epp4be Archives of General Psychiatry, online February 7, 2011.
Cannabis triggers earlier mental illness
By Danny Rose, AAP Medical Writer, AAP February 8, 2011, 7:01 am
The smoke is clearing on the link between cannabis and mental health problems, with the latest research showing how the drug can hasten the onset of schizophrenia by several years.
The study which reviewed data from 20,000 patients with a psychotic illness found those who smoked cannabis were diagnosed almost three years ahead of those who did not use the drug.
Dr Matthew Large, from the University of NSW’s School of Psychiatry and Prince of Wales Hospital, said the study was unique in scale and it should settle debate on whether cannabis could trigger earlier mental health problems.
“Results of this study are conclusive and clarify previously conflicting evidence of a relationship between cannabis use and the earlier onset of a psychotic illness,” Dr Large said.
“The results … provide strong evidence that stopping or reducing cannabis use could delay or even prevent some cases of psychosis.”
Dr Large, in a partnership with Melbourne’s St Vincent’s Hospital and the US-based George Washington University School of Medicine and Health Sciences, pooled patient data from more than 80 studies which had probed the link between psychotic illness and substance abuse.
The earlier studies had looked at the role played by cannabis, alcohol and other psychoactive substances but Dr Large’s meta-analysis was looking for an effect caused by cannabis alone.
Most of the patients involved had schizophrenia and, of those who were cannabis smokers, their diagnoses were seen to occur an average of 2.7 years earlier in their lives.
This time difference could be critical, Dr Large said, as it ensured psychotic symptoms were more likely to emerge during a person’s formative years and so compounded the lifelong impact.
“When you see people who develop schizophrenia in their 40s and they have family around them, and an occupation, often it is a much more simple matter of prescribing some medication and providing some education … it is not nearly as disabling,” Dr Large said.
“People who get it at 15 are much less likely to be able to hold down a job, to sustain relationships or complete their education.”
Cannabis is the most widely used illicit drug in Australia with a third of the population (33.5 per cent) reporting use at some time, according to a 2007 National Drug Household Survey.
Dr Large said it was also estimated about one third of those Australians with a diagnosed psychotic illness also report a history of cannabis use.
Just how cannabis use could trigger a psychotic illness was not yet known, though it could hinge on genetic as well as environmental factors or be the result of “disrupting” the brain during a period of “important neurological maturation”.
Dr Large also said it was also suspected, but not yet proven, that cannabis use made more people prone to psychotic illness.
He said those cannabis smokers who developed psychotic illness early could still have done so later in life had they never used the drug, and more research was needed.
“It took a long time to prove cigarette smoking caused lung cancer – it wasn’t really until 1965 that that information was firmly established,” Dr Large said.
“We are in that process of examining epidemiological associations of cannabis and this is another piece – quite a big piece – of the jigsaw.”
The research is published in the journal Archives of General Psychiatry.
Study underlines cannabis link to psychosis
By Kate Kelland – Wed Mar 2, 5:28 pm ET
LONDON (Reuters) – People who use cannabis in their youth dramatically increase their risk of psychotic symptoms, and continued use of the drug can raise the risk of developing a psychotic disorder in later life, scientists said on Wednesday.
In a 10-year study of links between cannabis use and psychosis, Dutch researchers found that cannabis use almost doubled the risk of later psychotic symptoms.
Experts commenting on the results said the major challenge for health authorities was to deter enough young people from using cannabis so that rates of psychosis could be reduced.
“This study adds a further brick to the wall of evidence showing that use of traditional cannabis is a contributory cause of psychoses like schizophrenia,” said Robin Murray of the Institute of Psychiatry at Kings College London, who was not involved in the research.
Wednesday’s findings, published in the British Medical Journal, echo research last year which found that young people who smoke cannabis for six years or more are twice as likely to have psychotic episodes, hallucinations or delusions.
Cannabis is the most commonly used illicit drug in the world, particularly among adolescents, and is increasingly linked to added risks of developing mental illness.
But scientists say it is not yet clear whether the link between cannabis and psychosis is causal, or whether it is because people with psychosis use cannabis to self-medicate to calm their symptoms.
For this study, a team of Dutch researchers led by Jim van Os from Maastricht University studied a random sample of 1,923 adolescents and young adults aged 14 to 24 years.
The study took place in Germany and the researchers separated out anyone who said they were already using cannabis and excluded those with pre-existing psychotic symptoms so they could look at links between new cannabis use and new psychosis.
They found that so-called “incident,” or new, cannabis use almost doubled the risk of new psychotic symptoms, even after accounting for factors such as age, sex, socio-economic status, use of other drugs and other psychiatric problems.
They also found that in those who were already using cannabis at the start of the study, continued use increased the risk of persistent psychotic symptoms. There was no evidence for self-medication effects since psychotic symptoms did not predict later cannabis use, they said.
Peter Kinderman, a professor of clinical psychology at the University of Liverpool, said the study suggested authorities should take “a cautious and thoughtful approach to cannabis legislation.”
“It’s important to remember that psychosis is a very complex bio-psycho-social phenomenon…but this important paper certainly reminds us that there’s a strong link to the use of cannabis,” he said in an emailed comment.
SOURCE: http://bit.ly/gBMvU4 British Medical Journal, online March 1, 2011.
Cannabis users face higher psychosis risk: study
Wed Mar 2, 3:14 am ET
LONDON (AFP) – Teenagers and young adults who use cannabis face increased risk of psychosis, research published in the British Medical Journal showed Wednesday.
Experts from Germany, the Netherlands and London’s Institute of Psychiatry studied 1,900 people aged between 14 and 24 over a period of eight years.
The study found that those who started using cannabis only after the experiment had begun and those who used it before and after both had a higher risk of psychotic symptoms than those who had never used it. “Cannabis use is a risk factor for the development of incident psychotic symptoms,” the report concluded.
“Continued cannabis use might increase the risk for psychotic disorder by impacting on the persistence of symptoms.”
Robin Murray, professor of psychiatric research at the Institute of Psychiatry, said the latest results backed up claims that the drug caused long-term psychological effects.
“This study adds incremental information to the already fairly solid evidence that continued use of cannabis increases risk of psychotic symptoms and psychotic illness,” he said.
“In short, this study adds a further brick to the wall of evidence showing that use of traditional cannabis is a contributory cause of psychoses like schizophrenia,” he added.