from the snuff-ignorance-before-it-spreads dept.
Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws (NORML), reports at AlterNet:
A new study identifying minor differences in the brain imaging of habitual marijuana consumers compared to non-users may be ideal for stimulating sensational headlines (e.g., "Regular pot smokers have shrunken brains, study says," Los Angeles Times, November 10), but tells us little in regard to whether pot poses actual health risks.
Specifically, an MRI scan revealed less gray matter in the orbital frontal cortex of pot-smoking subjects compared to those who had never used the drug. Researchers also identified increased connectivity between certain regions of the brain in regular marijuana users compared with non-users.
So precisely what do these findings tell us in regard to pot use and health? Not much. Since the study design is not longitudinal, investigators cannot determine whether these differences are caused by subject's cannabis use, whether these differences existed prior to subjects' ever trying cannabis, or whether these differences persist when users' cannabis consumption ceases.
Most importantly, investigators in this study failed to determine whether any of these differences are positively associated with any measurable adverse performance outcomes, such as cognitive performance or quality of life. It may be that these cannabis users are functioning in their daily lives in a manner that is indistinguishable from controls, in which case the imaging differences may hold little if any real-world significance.
Weed use is taking off as more states move to legalize it. And with all the buzz over medical marijuana, it's starting to gain an aura of healthfulness. But there are some serious health risks associated with frequent use. One of the more troubling ones is the risk of having a psychotic episode.
Several past studies have found that more frequent use of pot is associated with a higher risk of psychosis, that is, when someone loses touch with reality. Now a new study published Tuesday [open, DOI: 10.1016/S2215-0366(19)30048-3] [DX] in the The Lancet Psychiatry shows that consuming pot on a daily basis and especially using high potency cannabis increases the odds of having a psychotic episode later.
[...] The study also shows that three European cities — London, Paris and Amsterdam — where high potency weed is most commonly available actually have higher rates of new cases of psychosis than the other cities in the study. [...] The researchers identified 901 people aged 18 to 64 who were diagnosed with their first episode of psychosis between May 2010 and April 2015, at a mental health facility anywhere in 11 cities, including London, Paris, Amsterdam, Barcelona, other cities across Europe, and one site in Brazil.
The researchers then asked these individuals and a control group of 1,200-plus other healthy people about their habits, including their use of weed. "We asked people if they used cannabis, when did they start using it and what kind of cannabis," explains study author Marta Di Forti, a psychiatrist and clinician scientist at King's College London. People reported the names of weed strains they used, like skunk in the U.K., or the Dutch Nederwiet, which allowed the researchers to identify the THC content in each product through data gathered by the European Monitoring Center for Drugs and Drug Addiction and national data from the different countries.
The study found that those who used pot daily were three times more likely to have a psychotic episode compared to someone who never used the drug.
Related: Media Leaps to Questionable Conclusions from Study on the Effects of Marijuana on the Brain
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