The Chemistry of Modern Marijuana

Is low-grade pot better for you than sinsemilla?

First published September 3, 2013.

Australia has one of the highest rates of marijuana use in the world, but until recently, nobody could say for certain what, exactly, Australians were smoking. Researchers at the University of Sydney and the University of New South Wales  analyzed hundreds of cannabis samples seized by Australian police, and put together comprehensive data on street-level marijuana potency across the country. They sampled police seizures and plants from crop eradication operations. The mean THC content of the samples was 14.88%, while absolute levels varied from less than 1% THC to almost 40%.  Writing in PLoS ONE, Wendy Swift and colleagues found that roughly ¾ of the samples contained at least 10% total THC. Half the samples contained levels of 15% or higher—“the level recommended by the Garretsen Commission as warranting classification of cannabis as a ‘hard’ drug in the Netherlands.”

In the U.S., recent studies have shown that THC levels in cannabis from 1993 averaged 3.4%, and then soared to THC levels in 2008 of almost 9%. THC loads more than doubled in 15 years, but that is still a far cry from news reports erroneously referring to organic THC increases of 10 times or more.

CBD, or cannabidiol, another constituent of cannabis, has garnered considerable attention in the research community as well as the medical marijuana constituency due to its anti-emetic properties. Like many other cannabinoids, CBD is non-psychoactive, and acts as a muscle relaxant as well. CBD levels in the U.S. have remained consistently low over the past 20 years, at 0.3-0.4%. In the Australian study, about 90% of cannabis samples contained less than 0.1% total CBD, based on chromatographic analysis, although some of the samples had levels as high as 6%.

The Australian samples also showed relatively high amounts of CBG, another common cannabinoid. CBG, known as cannabigerol, has been investigated for its pharmacological properties by biotech labs. It is non-psychoactive but useful for inducing sleep and lowering intra-ocular pressure in cases of glaucoma.

CBC, yet another cannabinoid, also acts as a sedative, and is reported to relieve pain, while also moderating the effects of THC. The Australian investigators believe that, as with CBD, “the trend for maximizing THC production may have led to marginalization of CBC as historically, CBC has sometimes been reported to be the second or third most abundant cannabinoid.”

Is today’s potent, very high-THC marijuana a different drug entirely, compared to the marijuana consumed up until the 21st Century? And does super-grass have an adverse effect on the mental health of users? The most obvious answer is, probably not. Recent attempts to link strong pot to the emergence of psychosis have not been definitive, or even terribly convincing. (However, the evidence for adverse cognitive effects in smokers who start young is more convincing).

It’s not terribly difficult to track how ordinary marijuana evolved into sinsemilla. Think Luther Burbank and global chemistry geeks. It is the historical result of several trends: 1) Selective breeding of cannabis strains with high THC/low CBD profiles, 2) near-universal preference for female plants (sinsemilla), 3) the rise of controlled-environment indoor cultivation, and 4) global availability of high-end hybrid seeds for commercial growing operations. And in the Australian sample, much of the marijuana came from areas like Byron Bay, Lismore, and Tweed Heads, where the concentration of specialist cultivators is similar to that of Humboldt County, California.

The investigators admit that “there is little research systematically addressing the public health impacts of use of different strengths and types of cannabis,” such as increases in cannabis addiction and mental health problems. The strongest evidence consistent with lab research is that “CBD may prevent or inhibit the psychotogenic and memory-impairing effects of THC. While the evidence for the ameliorating effects of CBD is not universal, it is thought that consumption of high THC/low CBD cannabis may predispose users towards adverse psychiatric effects….”

The THC rates in Australia are in line with or slightly higher than average values in several other countries. Can an increase in THC potency and corresponding reduction in other key cannabinoids be the reason for a concomitant increase in users seeking treatment for marijuana dependency? Not necessarily, say the investigators. Drug courts, coupled with greater treatment opportunities, might account for the rise. And schizophrenia? “Modelling research does not indicate increases in levels of schizophrenia commensurate with increases in cannabis use.”

One significant problem with surveys of this nature is the matter of determining marijuana’s effective potency—the amount of THC actually ingested by smokers. This may vary considerably, depending upon such factors as “natural variations in the cannabinoid content of plants, the part of the plant consumed, route of administration, and user titration of dose to compensate for differing levels of THC in different smoked material.”

Wendy Swift and her coworkers call for more research on cannabis users’ preferences, “which might shed light on whether cannabis containing a more balanced mix of THC and CBD would have value in the market, as well as potentially conferring reduced risks to mental wellbeing.”

Graphics Credit: http://www.ironlabsllc.co/view/learn.php

Swift W., Wong A., Li K.M., Arnold J.C. & McGregor I.S. (2013). Analysis of Cannabis Seizures in NSW, Australia: Cannabis Potency and Cannabinoid Profile., PloS one, PMID: 23894589

A Chemical Peek at Modern Marijuana

Researchers ponder whether ditch weed is better for you than sinsemilla.

Australia has one of the highest rates of marijuana use in the world, but until recently, nobody could say for certain what, exactly, Australians were smoking. Researchers at the University of Sydney and the University of New South Wales recently analyzed hundreds of cannabis samples seized by Australian police, and put together comprehensive data on street-level marijuana potency across the country. They sampled police seizures and plants from crop eradication operations. The mean THC content of the samples was 14.88%, while absolute levels varied from less than 1% THC to almost 40%.  Writing in PLoS one, Wendy Swift and colleagues found that roughly ¾ of the samples contained at least 10% total THC. Half the samples contained levels of 15% or higher—“the level recommended by the Garretsen Commission as warranting classification of cannabis as a ‘hard’ drug in the Netherlands.”

In the U.S., recent studies have shown that THC levels in cannabis from 1993 averaged 3.4%, and then soared to THC levels in 2008 of almost 9%. THC loads more than doubled in 15 years, but that is still a far cry from news reports erroneously referring to organic THC increases of 10 times or more.

CBD, or cannabidiol, another constituent of cannabis, has garnered considerable attention in the research community as well as the medical marijuana constituency due to its anti-emetic properties. Like many other cannabinoids, CBD is non-psychoactive, and acts as a muscle relaxant as well. CBD levels in the U.S. have remained consistently low over the past 20 years, at 0.3-0.4%. In the Australian study, about 90% of cannabis samples contained less than 0.1% total CBD, based on chromatographic analysis, although some of the samples had levels as high as 6%.

The Australian samples also showed relatively high amounts of CBG, another common cannabinoid. CBG, known as cannabigerol, has been investigated for its pharmacological properties by biotech labs. It is non-psychoactive but useful for inducing sleep and lowering intra-ocular pressure in cases of glaucoma.

CBC, yet another cannabinoid, also acts as a sedative, and is reported to relieve pain, while also moderating the effects of THC. The Australian investigators believe that, as with CBD, “the trend for maximizing THC production may have led to marginalization of CBC as historically, CBC has sometimes been reported to be the second or third most abundant cannabinoid.”

Is today’s potent, very high-THC marijuana a different drug entirely, compared to the marijuana consumed up until the 21st Century? And does super-grass have an adverse effect on the mental health of users? The most obvious answer is, probably not. Recent attempts to link strong pot to the emergence of psychosis have not been definitive, or even terribly convincing. (However, the evidence for adverse cognitive effects in smokers who start young is more convincing).

It’s not terribly difficult to track how ditch weed evolved into sinsemilla. It is the historical result of several trends: 1) Selective breeding of cannabis strains with high THC/low CBD profiles, 2) near-universal preference for female plants (sinsemilla), 3) the rise of controlled-environment indoor cultivation, and 4) global availability of high-end hybrid seeds for commercial growing operations. And in the Australian sample, much of the marijuana came from areas like Byron Bay, Lismore, and Tweed Heads, where the concentration of specialist cultivators is similar to that of Humboldt County, California.

The investigators admit that “there is little research systematically addressing the public health impacts of use of different strengths and types of cannabis,” such as increases in cannabis addiction and mental health problems. The strongest evidence consistent with lab research is that “CBD may prevent or inhibit the psychotogenic and memory-impairing effects of THC. While the evidence for the ameliorating effects of CBD is not universal, it is thought that consumption of high THC/low CBD cannabis may predispose users towards adverse psychiatric effects….”

The THC rates in Australia are in line with or slightly higher than average values in several other countries. Can an increase in THC potency and corresponding reduction in other key cannabinoids be the reason for a concomitant increase in users seeking treatment for marijuana dependency? Not necessarily, say the investigators. Drug courts, coupled with greater treatment opportunities, might account for the rise. And schizophrenia? “Modelling research does not indicate increases in levels of schizophrenia commensurate with increases in cannabis use.”

One significant problem with surveys of this nature is the matter of determining marijuana’s effective potency—the amount of THC actually ingested by smokers. This may vary considerably, depending upon such factors as “natural variations in the cannabinoid content of plants, the part of the plant consumed, route of administration, and user titration of dose to compensate for differing levels of THC in different smoked material.”

Wendy Swift and her coworkers call for more research on cannabis users’ preferences, “which might shed light on whether cannabis containing a more balanced mix of THC and CBD would have value in the market, as well as potentially conferring reduced risks to mental wellbeing.”

Swift W., Wong A., Li K.M., Arnold J.C. & McGregor I.S. (2013). Analysis of Cannabis Seizures in NSW, Australia: Cannabis Potency and Cannabinoid Profile., PloS one, PMID: 23894589

Graphics Credit: http://420tribune.com

Decoding Dope

Why marijuana gets you high, and hemp doesn’t.

Cannabis sativa comes in two distinct flavors—smokeable weed, and headache-inducing hemp. The difference between hemp and smokeable marijuana is simple: Hemp, used for fiber and seed, contains only a tiny amount of THC, the primary active ingredient in the kind of cannabis that gets you high. I am old enough to recall the sad saga of California hippies driving through my natal state of Iowa, and filling their trunks with “ditch weed”—wild hemp that grows commonly along Iowa rural fencerows, and while it cannot get you high, it could, back then, get you arrested.

But the California hippies who ran afoul of the law in Iowa were not so stupid as it might seem. Even a marijuana connoisseur can have a hard time telling the difference between strong sinsemilla and wild hemp. Both varieties look similar, have similar growth patterns and flowering schedules, and a fresh bud of ditch hemp can look and smell enticingly like the real thing. Even the trichomes—the thousands of sticky, microscopic stalks that grow on the female flowers, each containing a bead of resin, like a crystal golf ball on a tee, containing mostly THC, in the case of pot, and mostly CBD, in the case of hemp—are also similar in appearance and growth behavior.

A study by a group of Canadian researchers, just published in Genome Biology, lays out the draft genome of marijuana, containing all of the plant’s hereditary information as encoded in DNA and RNA.In their article, Timothy Hughes, Jonathan Page and co-workers reported “a draft genome and transcriptome sequence of C. sativa Purple Kush.” (The genome and transcriptome can be browsed or downloaded at The Cannabis Genome Browser.) More than 20 plant genomes have now been sequenced, including corn and rice, but Cannabis sativa marks the first genomic sequencing of a traditional medicinal plant.

So how does it happen that one version of cannabis comes power packed, while the other version shoots blanks, so to speak? The researchers began with the modern facts of the matter: The THC content of medical and recreational marijuana is “remarkably high.” Research shows that median levels of THC in dried female flowers of Purple Kush (the strain used in the study) and other high-end variants now approach 11%, with some strains achieving a stratospheric 23% THC content by dry weight. Why can’t breeders pull any buzz out of ditch weed? How did cannabis split into two distinct subtypes? In an accompanying editorial entitled “how hemp got high,” Naomi Attar calls Cannabis sativa “a plant with a ‘split personality,' whose Dr. Jekyll, hemp, is an innocent source of textiles, but whose Mr. Hyde, marijuana, is chiefly used to alter the mind.” In brief, what are the biological reasons for the psychoactive differences between marijuana and hemp?

Co-lead author Jon Page, a plant biologist at the University of Saskatchewan, along with Tim Hughes of the Department of Molecular Genetics at the University of Toronto, compared the genomic information of Purple Kush, a medical marijuana favorite, with a Finnish strain of hemp called Finola, which was developed for oil seed production and contains less than 1% THC content. That is not enough THC to be mind-altering in any way. Instead, what Finola has in abundance is cannabidiol, or CBD, the other major ingredient in cannabis.

CBD isn’t considered psychoactive, but it does produce a host of pharmacological activity in the body. CBD shows less affinity for the two main types of cannabis receptors, CB1 and CB2, meaning that it attaches to receptors more weakly, and activates them less robustly, than THC.  The euphoric effects of marijuana are generally attributed to THC content, not CBD content. In fact, there appears to be an inverse ratio at work. According to a paper in Neuropsychopharmacology, "Delta-9-THC and CBD can have opposite effects on regional brain function, which may underlie their different symptomatic and behavioral effects, and CBD's ability to block the psychotogenic effects of delta-9-THC."

The kind of cannabis people want to buy has a high THC/low CBD profile, while the hemp chemotype is just the reverse—low THC/high CBD. While the medical marijuana movement has concentrated on Purple Kush and other high-THC breeds, medical researchers have often tilted towards the CBD-heavy variants, since CBD seems to be directly involved with some of the purported medicinal effects of the plant. So, CBD specifically does not produce the usual marijuana high with accompanying euphoria and forgetfulness and munchies. What other researchers have discovered is that pot smokers who suffer the most memory impairment are the ones smoking cannabis low in cannabidiol, while people smoking cannabis high in cannabidiol—cheap, seedy, brown weed—show almost no memory impairment at all. THC content didn't seem to matter. It was the percentage of CBD that controlled the degree of memory impairment, the authors of earlier studies concluded.

 The researchers found evidence in Purple Kush for “upregulation of cannabinoid ‘pathway genes’ and the exclusive presence of functional THCA synthase.” That means the reason hemp doesn’t get you high is because it is lacking the crucial enzyme—THCA synthase—that limits production of CBD and allows the production of THC to go wild. In contrast, cannabis strains producing high levels of THC—the Kushes and Hazes and White Widows and other seriously spendy variants—do have high levels of the enzyme that limits the production of CBD. Purple Kush gets you high because it has a built-in chemical brake on the production of CBD. Hemp doesn’t.

In a press release from the University of Saskatchewan, the researchers explain how they think this divergence came about: “Over thousands of years of cultivation, hemp farmers selectively bred Cannabis sativa into two distinct strains—one for fiber and seed, and one for medicine.” This intensive selective breeding resulted in changes in the essential enzyme for THC production, which “is turned on in marijuana, but switched of in hemp,” as Page put it. Furthermore, says co-leader Tim Hughes of the Department of Molecular Genetics at the University of Toronto, an additional enzyme responsible for removing materials required for THC production was “highly expressed in the hemp strain, but not the Purple Kush.” The loss of this enzyme in Purple Kush eliminated a substance “which would otherwise compete for the metabolites used as starting material” in THC production.

Without knowing the mechanics of it, underground growers and breeders have been steadily maximizing the cultivation of strains of cannabis high in THCA synthase, the result of which is a molecular blocking maneuver that maximizes THC production. This is great for getting high, but may not be the optimal breeding strategy for producing plants with medicinal properties.  Raphael Mechoulam, the scientist who first isolated and synthesized THC, has referred to plant-derived cannabinoids as a “neglected pharmacological treasure trove.”  The authors of this study agree, and have already identified some candidate genes that encode for a variety of cannabinoids with “interesting biological activities.” Such knowledge, they say, will “facilitate breeding of cannabis for medical and pharmaceutical applications.”

But cannabis of this kind may turn out to be low-THC weed. And that may be a good thing, some researchers believe. Marijuana expert Lester Grinspoon told Nature News: "Cannabis with high cannabidiol levels will make a more appealing option for anti-pain, anti-anxiety and anti-spasm treatments, because they can be delivered without causing disconcerting euphoria." (We’ll leave definitional issues about the effects of euphoria for another post.)

Finally, the authors strongly suggest that if it were not for “legal restrictions in most jurisdictions on growing cannabis, even for research purposes,” we would have known all of this stuff years ago, and would have been well on our way to developing “finer tailoring of cannabinoid content in new strains of marijuana,” as Nature News Blog describes it.

van Bakel H, Stout JM, Cote AG, Tallon CM, Sharpe AG, Hughes TR, & Page JE (2011). The draft genome and transcriptome of Cannabis sativa. Genome biology, 12 (10) PMID: 22014239
Photo Credit:http://www.medicinalgenomics.com/

Marijuana and Memory

Do certain strains make you more forgetful?

Cannabis snobs have been known to argue endlessly about the quality of the highs produced by their favorite varietals: Northern Lights, Hawaiian Haze, White Widow, etc. Among dedicated potheads, debates about the effects of specific cannabis strains are often overheated, and, ultimately, kind of boring. It's a bit like listening to a discussion of whether the wine in question evinces a woody aftertaste or is, instead, redolent of elderberries. For most people, the true essence of wine drinking is pretty straightforward: a drug buzz, produced by a 12 to 15 % concentration of ethyl alcohol derived from grapes, which can be had in a spectrum of varietal flavors.

However, there is no doubting that, unlike the case of wine, different strains of marijuana can have markedly different psychoactive effects. With weed, it's not just a matter of taste.

Over the past couple of years, the cannabis debate has taken a nasty turn, after British scientists published several controversial studies suggesting that high-THC "skunk" cannabis was responsible for increased mental problems among young people--including an increased risk of developing the symptoms of schizophrenia. British drug policy makers have continued to lead the charge on this, with mixed results. See my earlier post.

Recently, a study published in the British Journal Of Psychiatry concluded that marijuana
high in THC--including so-called "skunk" cannabis--caused markedly more memory impairment than varieties of marijuana containing less THC.

In an article at Nature News, Arran Frood spelled out the details of the study:

"Curran and her colleagues traveled to the homes of 134 volunteers, where the subjects got high on their own supply before completing a battery of psychological tests designed to measure anxiety, memory recall and other factors such as verbal fluency when both sober and stoned. The researchers then took a portion of the stash back to the laboratory to test how much THC and cannabidiol it contained....  Analysis showed that participants who had smoked cannabis low in cannabidiol were significantly worse at recalling text than they were when not intoxicated. Those who smoked cannabis high in cannabidiol showed no such impairment."

The two main ingredients in cannabis are THC and cannabidiol (CBD). CBD shows less affinity for the two main types of cannabis receptors, CB1 and CB2, meaning that it attaches to receptors more weakly, and activates them less robustly, than THC.  The euphoric effects of marijuana are generally attributed to THC content, not CBD content. In fact, there appears to be an inverse ratio at work. According to a paper in Neuropsychopharmacology, "Delta-9-THC and CBD can have opposite effects on regional brain function, which may underlie their different symptomatic and behavioral effects, and CBD's ability to block the psychotogenic effects of delta-9-THC."

So, CBD specifically does not produce the usual marijuana high with accompanying euphoria and forgetfulness and munchies. What the researchers found was that pot smokers suffering memory impairment and those showing normal memory "did not differ in the THC content of the cannabis they smoked. Unlike the marked impairment in prose recall of individuals who smoked cannabis low in cannabidiol, participants smoking cannabis high in cannabidiol showed no memory impairment."

As far as memory goes, THC content didn't seem to matter. It was the percentage of CBD that controlled the degree of memory impairment, the authors concluded. "The antagonistic effects of cannabidiol at the CB1 receptor are probably responsible for its profile in smoked cannabis, attenuating the memory-impairing effects of THC. In terms of harm reduction, users should be made aware of the higher risk of memory impairment associated with smoking low-cannabidiol strains of cannabis like 'skunk' and encouraged to use strains containing higher levels of cannabidiol."

The idea that cannabidiol may protect against THC-induced memory loss is still quite speculative.  Other research has suggested that a paucity of CB1 receptors may be protective against memory impairment. Marijuana growers select for high-THC strains, not high-CBD strains, and thus there is little data available about the CBD levels of most marijuana.

An earlier study in Behavioural Pharmacology by Aaron Ilan and others at the San Francisco Brain Research Institute did not find any connection between memory and CBD content. However, Ilan speculated in the Nature News article that the difference might have been due to methodology: In Britain, the subjects were studied using marijuana of their own choosing.  In the U.S., National Institute of Health research policy has decreed that marijuana for official research must be supplied by the National Institute on Drug Abuse (NIDA). And if there is one thing many researchers seem to agree on, it is that NIDA weed "is notorious for being low in THC and poor quality."

But CBD still does something, and that something just might be pain relief.  Lester Grinspoon, a long-time marijuana researcher at Harvard Medical School, thinks that if the study proves out, it could have an important impact on the medical use of marijuana. Also quoted in Nature News, Grinspoon said: "Cannabis with high cannabidiol levels will make a more appealing option for anti-pain, anti-anxiety and anti-spasm treatments, because they can be delivered without causing disconcerting euphoria."

Morgan, C., Schafer, G., Freeman, T., & Curran, H. (2010). Impact of cannabidiol on the acute memory and psychotomimetic effects of smoked cannabis: naturalistic study The British Journal of Psychiatry, 197 (4), 285-290 DOI: 10.1192/bjp.bp.110.077503

Graphics Credit: http://sites.google.com