What's in Your Marijuana? Some Pot Doesn't Rot Your Memory
Want fewer "Dude, where's my car?" moments but not ready to give up the weed? A new study published in the British Journal of Psychiatry suggests that variations in the chemical makeup of different strains of marijuana are associated with different levels of cognitive impairment while high.
Tetrahydocannabinol (THC) is commonly recognized as the ingredient in marijuana that causes a "high" in users, but researchers have long known that pot contains other active substances as well. While THC can cause hallucinations and paranoia, another chemical found in marijuana, cannabidiol (CBD), is believed to be responsible for the calmer, sedating part of the experience. The two chemicals have opposing effects on one of the brain receptors affected by cannabis, the CB1 receptor.
To determine the effect of different levels of CBD, researchers studied 134 cannabis-using volunteers while they smoked their own stash of marijuana, at home. They gave them various cognitive tests, either while wasted or abstinent. Then, they took samples of the pot back to the lab for testing.
The amount of cannabidiol contained in the marijuana varied widely — from 0.14% or less to 0.75%. Researchers found that smokers who toked the weed with the lowest CBD had significant impairments in their ability to recall words, while those whose pot had higher levels of the chemical had no impairment at all. (The study authors controlled for any variance in levels of THC.)
A previous study had not found this difference — but the author of that research told Nature News that he thinks this is because his group studied only the marijuana supplied by the U.S. government, rather than the much more varied weed smoked by illegal users.
Another variable might be how often the users typically smoke: a recent study of frequent marijuana users found that while cannabis did slow reaction time, it didn't have a significant effect on cognitive performance.
Interestingly, however, unlike previous studies, the new research did not find that CBD reduced the hallucinatory and paranoia-inducing effects of THC that can be associated with psychotic episodes.
While some growers have bred "skunk" marijuana, which has extremely high levels of THC, less intense varietals with increased CBD can also be found. If this research holds up, the mellower high may be the smarter choice.
- Article from TIME.
by Fred Gardner, Counterpunch
Mahmoud Elsohly, PhD, is best known for supervising the only federally-sanctioned cannabis grow site in the U.S., a one-acre plot on the University of Mississippi campus. ElSohly also has a lucrative contract with the National Institute on Drug Abuse to analyze cannabis samples seized by law enforcement in raids. "Potency Trends of D9-THC and Other Cannabinoids in Confiscated Cannabis Preparations from 1993 to 2008," an article in the September issue of Forensic Sciences co-authored by ElSohly, confirms that levels of psychoactive THC have risen over the years, especially in sinsemilla, while levels of non-psychoactive Cannabidiol (CBD) have dwindled.
This trend may change in states that have legalized medical cannabis use because doctors and patients are beginning to create demand for CBD, which is known to have anti-inflammatory properties. Some of the plants confiscated and/or destroyed by law enforcement during raids in Northern California last week were reportedly CBD-rich "Stinky Purple" and "Cotton Candy/Diesel." Their names might not sound medicinal, but their CBD content was around 9% and 6.5% respectively, and doctors in the Society of Cannabis Clinicians plan to study their effects.
The two strains of interest were —and are— being cultivated in Round Valley, near the town of Covelo in northern Mendocino County. Other growers in the area have more SP and CC/D nearing harvest.
Studies published in medical and scientific journals suggest that CBD could be useful in easing the symptoms of rheumatoid arthritis, diabetes, nausea, and inflammatory bowel disorders, among other difficult-to-control conditions. CBD also has demonstrated neuroprotective effects, and its anti-cancer potential is being explored at the California Pacific Medical Center and other academic research centers.
Of the approximately 10 CBD-rich strains identified to date in California and Montana, Stinky Purple has the highest CBD-to-THC ratio, 8-to-1. In other words, some of what the narcs got in Round Valley was unambiguously medical cannabis that would not get anyone stoned and that doctors and patients intend to evaluate. Instead, it will be incinerated and sent to the evidence room (from whence much of it will mysteriously disappear). Samples will of course be shipped to Team ElSohly in Mississippi, and in a year or two an article may appear in Forensic Sciences suggesting that the decades-long trend of diminishing CBD in U.S. sinsemilla has been reversed.
As for the journal article by doctors evaluating CBD in the treatment of arthritis, that will take a while longer to produce. Such are the priorities of a police state.
CBD Levels Highest in Hash
As reported by ElSohly et al, 46,211 Cannabis samples provided by the DEA over the years were grouped by the Mississippi team into product categories —"marijuana," "sinsemilla," "hashish," "hash oil," "Thai sticks," and "ditchweed."
Overall, THC content was found to have increased steadily, year-by-year, from a mean of 3.4% in 1993 to 8.8% in 2008.
Levels of the so-called "minor cannabinoids" -CBC, CBD, CBN, CBG and THCV- were also monitored. "CBD is the major cannabinoid found in ditchweed," the authors reported, "and is present in elevated amounts in intermediate type cannabis (moderate levels of both D9-THC and CBD) used to make hashish."
What the authors call "drug-type cannabis" is high in THC. "Intermediate type cannabis" refers to strains grown in Morocco and Afghanistan that contain roughly equal amounts of THC and CBD and for processing into hashish that gets exported to Europe and the U.S. "Ditchweed," defined as "fiber type wild cannabis found in the Midwestern region of the U.S.," has more CBD than THC.
The Ol' Miss team reported, "The cannabinoid content of hashish and hash oil samples shows that, while hashish is prepared from intermediate type cannabis, hash oil is prepared from drug-type cannabis (high D9-THC and low CBD levels)." This may not be accurate, according to industry sources —hashish and hash oil are both made in the U.S. from the trim and leaves of "drug-type plants" high in THC.
The mean concentration of CBD in all seized products did not vary much over 16 years —from 0.3% to 0.5%— and there was no steady increase. The percent of CBD detected in samples seized in '03, '04 and '05 was 0.5% and then dropped to 0.4% in '06, '07 and '08. CBD levels were even lower in confiscated marijuana and sinsemilla —in the 0.2-3% range.
"Ditchweed" was found to contain from 1.5% to 2.4% CBD. The highest levels were found in confiscated hashish, ranging from 0.8% (2004) to 4.9% (1999).
Cannabis Potency in the UK
Hashish imported from Morocco and Afghanistan was the only form of cannabis found to contain significant levels of CBD, according to a study by British researchers —"Potency of D9-THC and Other Cannabinoids in Cannabis in England in 2005: Implications for Psychoactivity and Pharmacology"— in the Journal of Forensic Science, January 2008. Here's the abstract:
"Gas chromatography was used to study the cannabinoid content ('potency') of illicit cannabis seized by police in England in 2004-5. Of the 452 samples, indoor-grown unpollinated female cannabis ("sinsemilla") was the most frequent form, followed by resin (hashish) and imported outdoor-grown herbal cannabis (marijuana). The content of herbal cannabis and resin was 2.1% and 3.5% respectively. The median 13.9% THC content of sinsemilla was significantly higher than that recorded in the UK in 1996-98. In sinsemilla and imported herbal cannabis, the content of the antipsychotic cannabinoid cannabidiol (CBD) was extremely low. In resin, however, the average CBD content exceeded that of THC, and the relative proportions of the two cannabinoids varied widely between samples. The increases in average THC content and relative popularity of sinsemilla cannabis, combined with the absence of the anti-psychotic cannabinoid CBD, suggest that the current trends in cannabis use pose an increasing risk to those users susceptible to the to those users susceptible to the harmful psychological effects associated with high doses."
Two authors of the UK potency study work for GW Pharmaceuticals, and GW also provided lab and statistical support. GW is marketing Satvex, an extract containing equal amounts of THC and CBD, and has an obvious interest in emphasizing the "anti-psychotic" potential of CBD.
"CBD has pharmacological properties but is not psychoactive," write David Potter, Peter Clark, and Marc Brown. "Based on pre-clinical and clinical data, CBD is notable for its ability to antagonize the psychoactive effect of THC. Its presence would be suspected of lowering the recreational value of cannabis." They cite studies linking heavy THC consumption to "an increased risk of later developing schizophrenia-like psychoses."
Lester Grinspoon, MD, is among those who question that link.
The UK study involved samples seized by the police in Derbyshire, Kent, Central London, Merseyside, and Sussex. The investigators found that more than half were "Sinsemilla (Skunk)," grown indoors.
"The CBD content of sinsemilla was typically very low and fell below detectable levels (0.1%) in the majority of samples.
"THC was also the dominant cannabinoid in herbal cannabis and CBD levels were mostly below the detectable threshold.
"Cannabis resin (hashish) had a very different cannabinoid profile... CBD was the dominant cannabinoid in this material, with average THC contents being marginally less."
This higher level of CBD reflects the fact that most of the hashish in England was imported. There is nothing in the hash making process that would alter the CBD-to-THC ratio. Nor is there any aspect of cultivation that alters the ratio, according to a knowledgable botanist. "It's genetics, genetics, genetics," he says.
Potter et al write:
"Research suggests that the production of THC or CBD from the common precursor CBG is closely controlled by two co-dominant alleles at a single locus. As a result, cannabis plants can be identified as belonging to any one of three chemotypes. They can be THC dominant, CBD dominant, or containing an approximately equal mixture of the two. The majority of the cannabis resin would appear to be prepared from landrace populations of plants which contain all three chemotypes. herbal cannabis and sinsemilla appear almost entirely derived from the THC-dominant chemotype."
The THC-to-CBD ratio was found to vary widely among the samples.
"Cannabis resin samples ranged in THC content from 0.44% to 10.76% and in CBD from 0.36% to 6.97%... As CBD is reported to attenuate the psychoactive effects of THC, the wide range of THC:CBD ratios would be expected to variably alter the potential psychoactive and pharmacologial effects of the THC within the resin. This emphasises that the potential psychoactive and pharmacological properties of cannabis resin should not be simply judged by the THC content alone."
The authors conclude,
"of the three principle forms of cannabis, sinsemilla commonly had the highest THC content and almost totally lacked CBD. Had CBD been present it would have reduced the psychoactive potential of this material. In addition to having increased in potency, sinsemilla also appears to have become the most widely used form of cannabis. The current trends in cannabis use suggest that those susceptible to the harmful psychological effects associated with THC are at ever greater risk. This is due to the combined rise in potency and popularity of sinsemilla and the absence of CBD in this product."
- Article from Counterpunch.