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hippocampus

  • by Paul Armentano, NORML Deputy Director April 30, 2018

    Marijuana researchThe frequent use of cannabis is not associated with changes in brain structure, according to data published online ahead of print in the journal Addiction.

    An international team of scientists from Australia, the United Kingdom, and the United States assessed the relationship between habitual cannabis exposure and grey matter volumes in seven regions of the brain – including the thalamus, hippocampus, amygdala, and the nucleus accumbens – in two large population-based twin samples.

    Researchers reported, “[N]ormal variation in cannabis use is statistically unrelated to individual differences in brain morphology as measured by subcortical volume.”

    By contrast, the repeated use of nicotine was positively associated with significantly smaller thalamus volumes in middle-aged males.

    Authors concluded: “This is the largest exploratory analysis integrating brain imaging with self-report cannabis and comorbid substance use data. After correcting for multiple testing, there was no effect of cannabis use on the volume at any subcortical region of interest in young adults or middle-aged males. … In the context of expanding medicalization and decriminalization and the concerns surrounding the consequences of increased cannabis availability, our findings suggest that normal variation in cannabis use is statistically unrelated to brain morphology as measured by subcortical volumes in non-clinical samples.”

    The findings are consistent with those of prior brain imaging studies reporting that cannabis exposure appears to have little to no significant adverse impact upon brain morphology — particularly when compared to the dramatic effects associated with the alcohol exposure.

    The study’s findings fail to replicate those of a well-publicized 2014 paper which alleged that even casual marijuana exposure may be linked to brain abnormalities, particularly in the amygdala.

    Last week, a meta-analysis of 69 separate studies reported that cannabis exposure in adolescents and young adults is not associated with any significant, residual detrimental effects on cognitive performance. The results from a pair of recently published longitudinal twin studies similarly report that cannabis use is not independently associated with any residual change in intelligence quotient or executive function.

    An abstract of the study, “Testing associations between cannabis use and subcortical volumes in two large population-based samples,” appears online here.

  • by Paul Armentano, NORML Deputy Director June 3, 2008

    Ever wonder why the studies purporting to ‘prove’ marijuana’s health risks only recruit subjects who smoke pot 24 hours a day, seven days a week?

    Heavy marijuana use shrinks brain parts
    via Reuters  

    Brain scans showed the hippocampus and amygdala were smaller in men who were heavy marijuana users compared to nonusers.  … The men had smoked at least five marijuana cigarettes daily for on average 20 years.    

    The answer: If they didn’t, there wouldn’t be any purported risks left to write about.

    I mean, seriously, imagine if these scientists had tried recruiting 15 subjects who drank at least five shots of vodka every day for 20 years? That is, if they could find 15 subjects who were still alive.

    Marijuana may up heart attack, stroke risk
    via Reuters

    Heavy marijuana use can boost blood levels of a particular protein, perhaps raising a person’s risk of a heart attack or stroke, U.S. government researchers said on Tuesday. …The marijuana users in the study averaged smoking 78 to 350 marijuana cigarettes per week.

    The study did not look at whether the heavy marijuana users actually had heart disease. 

    So here we go again. Three-hundred and fifty joints per week?! Who are these people? And what’s with the caveat at the end of the story? If the purpose of the study is to assess whether there might be a link between ridiculously heavy pot use and heart disease, then why not, you know, look to see whether the subjects actually suffered from heart disease? (Likely answer: Aside from the abnormal protein level, the patients were probably otherwise healthy.)

    Bottom line: smoking pot all day, every day probably isn’t good for you (though I find it interesting that, even among the most prolific pot users, most of the herb’s purported dangers are either speculative or are only apparent on hyper-sensitive brain scans and multi-tiered neurocognitive tests). Fortunately, 99.9 percent of pot smokers don’t behave this way.

    And no, it’s not prohibition that curbs their use habits; it’s the recognition that too much pot is not conducive to an otherwise healthy, responsible lifestyle (just as pounding five shots a day wouldn’t be conducive to, well, life).

    So what lesson can be learned from the two studies above (aside from the fact that our government has no interest in investigating the health of ordinary cannabis consumers)? It’s that pot, like alcohol, is best consumed in moderation, and that pot prohibition — even when compared to the excessive use of the drug itself — still poses the greatest threat to health.