Teen Grey Matter and Cannabis Use
Posted by Warm Southern Breeze on Thursday, January 17, 2019
In a recently published article entitled “Grey Matter Volume Differences Associated with Extremely Low Levels of Cannabis Use in Adolescence,” in the Journal of Neuroscience, 14 January 2019 edition, pp3375-17, researchers wrote in part that “We identified extensive regions in the bilateral medial temporal lobes as well as the bilateral posterior cingulate, lingual gyri, and cerebellum that showed greater GMV in the cannabis users.”
News items related to that newly published research are focusing upon that singular line as if it’s something negative. Since when did INCREASED grey matter become something dangerous, or cause for concern? Colloquially, the term “grey matter” is used to describe the brain, and by extension, brain power. So let’s examine this matter (no pun intended) in more detail.
But before proceeding further, it bears mentioning that adolescents should NOT be consuming cannabis, neither alcohol, nor tobacco. And try as much as we want, we will not ever stop underage consumption of any adults-only substance. The BEST we can do is to educate them, and others, of potential risks involved in its use – especially and particularly underage use – and deny them opportunities to consume alcohol, tobacco, and cannabis. THAT is a strategy which has PROVEN to work, because the trite “Just say ‘no'” has never worked, nor will it ever.
Dr David Robert Grimes is a physicist, cancer researcher and science writer, who was the joint recipient of the 2014 Nature / Sense About Science Maddox Prize and wrote in a brief anti-marijuana article dated 15th May 2017 entitled “The rise of the cannabis cult: don’t believe the hype about medical marijuana” that “As a general rule of thumb, anything that has a biological impact is likely to have some potential ill effect, and cannabis is no exception.”
His comment bears merit.
For example, the very substance which is absolutely necessary to life which is called “water” (or dihydrogen monoxide, for the nerdy) is responsible for countless deaths, not only by victims drowning in bodies of water, but by excessive consumption of water in a short period of time.
Called “water toxemia,” or water poisoning, there are numerous documented cases of deaths from drinking an excessive amount of water quickly.
As cited in Scientific American June 21, 2007, in a fraternity hazing at California State University, Chico in 2005, a healthy 21-year-old man died after he was forced to drink excessive amounts of water between rounds of push-ups performed in a cold basement.
In 2007, Jennifer Strange, a 28-year-old California woman died after competing in a radio station’s on-air water-drinking contest following her consumption of six liters of water in three hours in a strange, dangerous, even abusive radio contest called the “Hold Your Wee for a Wii” (a Nintendo game console). Immediately following her “win,” she vomited, went home with a splitting headache, and died… from water intoxication.
And a 2005 study published in the New England Journal of Medicine – “Hyponatremia among Runners in the Boston Marathon” – found that “thirteen percent had hyponatremia (a serum sodium concentration of 135 mmol per liter or less); 0.6 percent had critical hyponatremia (120 mmol per liter or less). If our sample was representative of the overall 2002 Boston Marathon field of runners, we would estimate that approximately 1900 of the nearly 15,000 finishers had some degree of hyponatremia, and that approximately 90 finishers had critical hyponatremia.”
Hyponatremia is a condition in which the concentration ratio of sodium in the blood becomes dangerously low, which can lead to sudden cardiac arrest, or other seriously life-threatening conditions, and in the study of marathon runners, was caused by drinking too much water.
Regarding the recently cited research on marijuana use and teen brains, an example of news arising from it which obliquely and surreptitiously claims danger from “just one or two instances of cannabis use” appeared on the Science Daily website January 14, 2019 and was headlined “Teen brain volume changes with small amount of cannabis use, study finds.”
The article’s summary from the Larner College of Medicine at the University of Vermont stated that “At a time when several states are moving to legalize recreational use of marijuana, new research shows that concerns about the drug’s impact on teens may be warranted. The study shows that even a small amount of cannabis use by teenagers is linked to differences in their brains.”
The Science Daily article stated in part that “The new study, part of a long-term European project known as IMAGEN, included 46 kids who reported having used cannabis once or twice by age 14. Their brains showed more gray matter volume in areas where cannabis binds, known as cannabinoid receptors, compared to the kids who didn’t use the drug. The biggest differences in gray matter were in the amygdala, which is involved in fear and other emotion-related processes, and in the hippocampus, involved in memory development and spatial abilities.”
The original research is linked here.
Grey Matter Volume Differences Associated with Extremely Low Levels of Cannabis Use in Adolescence. The Journal of Neuroscience, 2019; 3375-17 DOI: 10.1523/JNEUROSCI.3375-17.2018
http://www.jneurosci.org/content/early/2019/01/14/JNEUROSCI.3375-17.2018
Regarding the research, there are numerous practically blatant problems, not the least of which is the small study size – 46.
First, let’s examine this opening statement, that “GMV in the temporal regions was associated with contemporaneous performance on the Perceptual Reasoning Index and with future generalized anxiety symptoms in the cannabis users.”
GMV is Grey Matter Volume, and is a measure cited in various reports to measure the density of brain cells in a particular region. (You would think that “MORE” would be better, right?)
Research has shown the distribution of gray matter in humans is significantly heritable (i.e., you can get it from your parents), yet there is also a strong environmental influence. Recent studies have found an increased volume of gray matter in Broca’s area of professional musicians, which apparently reflects, at least in part, the number of years devoted to musical training.
As well, an increased volume of gray matter in the anterior hippocampus (a brain region involved in spatial navigation) of experienced London taxi drivers was found, with increased volume correlated with length of taxi-driving experience.
And increased gray matter volume was associated with an increase in the development of new brain cells in older adults who underwent an aerobic training program compared with those who did not.
So immediately, we see that an increase in gray matter volume is not necessarily anything to be worried about, and find rather, that it’s a positive sign.
The Perceptual Reasoning Index is an expression and measure of non-verbal (perceptual) and fluid reasoning, spatial processing, visual-motor integration, and the ability to learn new information, and assesses the ability to examine a problem, use visual-motor and visual-spatial skills, organize thoughts, and develop and test solutions, and can indicate a preference for visual information or kinesthetic learning and a comfort with new situations.
Contemporaneous simply means “originating, existing, or happening during the same period of time.”
So far, the researchers have told us that the subjects had a brain, and that their brain enabled them to take a test which demonstrated, to some extent, their ability to solve problems, and was related to time-space perceptions. Brilliant, eh?
In the next phrase, they say that “and with future generalized anxiety symptoms in the cannabis users.”
Generalized Anxiety Disorder is fairly innocuous, and in adults occurs only in about 3% of the population, and may be characterized by tired feelings (malaise), unrest/fidgeting, headaches, upset stomach, irritability/restlessness, difficulty sleeping, and/or rashes – certainly nothing life-threatening. And as young teens that are developing life-coping skills and strategies, it wouldn’t be uncommon for them to experience any, or even all of those symptoms at some time in their adolescence, or even as young adults.
So far, it sounds like the researchers have identified no serious problem.
Next, there are numerous questionable, or even false, statements the authors make in the introduction to their work.
The very first statement and claim they make is that “Rates of cannabis use among adolescents are high, and are increasing concurrent with changes in the legal status of marijuana and societal attitudes regarding its use.”
The authors do not define what constituted or defined “high” for “rates of cannabis use among adolescents,” nor do they provide any baseline data to back up the specious claim. Next, their use of the word “high” to describe elevated levels, or increased rates must have a starting point, or a known value, which ideally ought to be zero, but most often is not. Thus, their statement suggests there is a known value above zero which is commonplace, accepted, or an acceptable standard. But again, they cite no authority, nor research to substantiate their claim.
According to the Substance Abuse and Mental Health Services Administration (SAMHSA), “most teens aren’t smoking marijuana.” As found in Results from the 2012 National Survey on Drug Use and Health: Summary of National Findings “5 out of 6 12-to-17 year olds have never tried marijuana.” That’s 83.3%.
And longitudinal research done annually since 1971 by the Substance Abuse and Mental Health Services Administration (SAMHSA), as the National Survey on Drug Use and Health (NSDUH) does NOT mention anything remotely related to the researchers assertion that “rates of cannabis use among adolescents are high…”
In fact, long-term (longitudinal) epidemiological research (epidemiology is the study of factors afecting health) published in “Monitoring the Future, National Survey Results on Drug Use 1975-2017, Volume 1, Secondary School Students,” also known as the National High School Senior Survey, shows that from 1975 to 2017, 60% to 63.1% of 12th Graders responded not having used marijuana, respectively. The range was 49.4% to 76.8%, with an average of 63.5%.
What IS alarming, however, is underage consumption rates of alcohol, which is significantly greater than the rate of cannabis experimentation, and which has demonstrably and conclusively proven to have negative health repercussions.
Their next statement is true, that “Recreational cannabis use is understudied, especially in the adolescent period when neural maturation may make users particularly vulnerable to the effects of Δ-9-tetrahydrocannabinol (THC) on brain structure.”
Researchers whom have examined the matter have concluded similarly, that there is an abysmal dearth of research upon cannabis. Slowly, that’s changing. But Americans’ adoption of the useless “Just say ‘no'” campaign has done more to damage research & science than it has to deter illicit substance use. It’s the proverbial ostrich-head-in-the-sand approach.
However, that being said, renown researcher Jim van Os of the University of Maastricht, Netherlands, is considered by many to be the world’s preeminent researcher of the effects of cannabis upon the brain, and its effects upon the human being.
As the Lead Researcher, Professor Jim van Os followed 2437 people aged 14 – 24 four years, and published his findings in the British Medical Journal, which revealed that when controlled for other events, 51% of cannabis users experienced schizophrenic symptoms versus 26% of non-users.
He and other researchers adjusted for factors such as social and economic status and use of other drugs, tobacco, and alcohol, and found that cannabis use overall moderately increased the risk of psychotic symptoms. However, in those with a predisposition for psychosis, the effect was much stronger.
Researchers were emphatic that their findings did not support the theory that the link was simply a matter of people with such a predisposition being more likely to use cannabis, rather than cannabis in some way making psychosis more likely. And they found as well that there was little evidence that people who were genetically vulnerable to psychosis were any more likely to indulge in drug taking.
Speaking of the research, Lead Researcher Professor Jim van Os told the BBC News website in 2004 that using cannabis was not a good idea for those with a predisposition toward mental upset, saying that “If there is a family or personal history of mental frailty – stay away form it!”
Dutch researchers also led by Jim van Os from Maastricht University conducted a 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.
NOTE: It should be borne in mind, that the majority of all such research cited here, focused upon the long-term, or delayed effects of marijuana usage 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 increased risks for psychoses in later life (after controlling for family history, etc.) is experienced when the immature brain is exposed to cannabis.
• Cannabis and schizophrenia. A longitudinal study. – Lancet, 1987 – 15 yr, 45,570 subject study of Swedish soldiers demonstrated significant risk for schizophrenia when compared to non-users and controlled for other factors, increased the risk of suicide 400%.
• A 35-year longitudinal study published in the British Journal of Psychiatry, found that schizophrenia rates doubled among marijuana users in South London. 2003 Jan 1; 182():45-9
• New Zealand researchers found that those whom had smoked marijuana 3x by age 15 were 300x more likely to develop schizophrenia, and that cannabis consumption was a factor in 80% of schizophrenia cases

The title of this fear-mongering bit by a religious tract writer in St. Paul, MN, is from a fear-mongering Op-Ed by Harry Anslinger, then Narcotics Bureau Chief of the U.S. Treasury, which was originally published July 1937 in “The American” magazine, and later in “The Reader’s Digest,” February 1938. A notorious racist, Anslinger had a hand-in-glove working relationship with yellow journalism newspaper magnate William Randolph Hearst, whose papers prominently featured tabloid style journalism, were largely devoid of facts, and focused upon often-contrived, and largely exaggerated sensationalistic and salacious stories in order to sell more newspapers. The modern equivalent would be the National Enquirer, whose owner David Pecker is a close personal friend of Donald Trump.
So again, we KNOW there are risks associated with underage consumption of cannabis, and for those reasons, and others now unknown, it should be avoided, and discouraged by educating children about the dangers it poses to them, what it could possibly cause to happen later in life, etc.
Much of the fear-mongering which has surrounded cannabis has been a direct result of anti-immigrant and racist sentiment which swept over the United States in the mid-to-late 1930’s – a period in which cannabis and its consumers were vilified in horrific fashion, which today is considered maudlin, corny, or even outright ridiculous. However, the residual effects of its racist underpinnings, sadly, remain with us today.
Again, slowly, but surely, that’s also changing – and that’s a good thing, and positive finding.
However, it should similarly be borne in mind that adults have an inherent right to make adult decisions – whether informed, or not – and should be allowed to do so responsibly.
If that decision is to responsibly consume cannabis, alcohol, tobacco, and/or to exercise, or not, etc., so be it.
It is NOT now, nor has it ever been the role of any government to be a so-called “nanny state” to continually watch over adults to prevent them from making independent decisions – good, or bad – for themselves.
In the mean time, enjoy watching Jim van Os TEDx talk about schizophrenia.
His ideas about the “schizo” family of related diagnoses is significantly and positively influencing the way that mental health professionals and physicians consider how the brain works.
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