The Future of Medicinal Marijuana - Less High (THC), More Healing (CBD)

Hashish Smokers by Gaetano Previati, 1877. Private collection. Photo by Getty Images

I'm sure this will harsh the high of some dedicated marijuana users, but the future of good weed lies in reducing the THC content through breeding while increasing the CBD content.

• THC: tetrahydrocannabinol, the primary psychoactive compound in cannabis and is what causes the subjective "high"
• CBD: cannabidiol, produces the calming, anti-anxiety effects of the drug

The illicit marijuana market has systematically increased the THC content by 10-15% over the last decade or so. At the same time, there has been a significant reduction of CBD, sometimes to levels as low as 0.1%. A recent article in The Guardian (UK) suggests that this high-THC/low-CBD marijuana, "skunk weed," is something new, but it was the goal 30 years ago when I was still smoking weed.

From Wikipedia:

Decades ago, growers in the US bred CBD almost entirely out of cannabis plants because their customers preferred varietals that were more mind-altering due to a higher THC, lower CBD content.[50] To meet the demands of medical cannabis patients, growers are developing more CBD-rich strains.[52]

In November 2012, an Israeli medical cannabis facility announced a new strain of the plant which has only cannabidiol as an active ingredient, and virtually no THC, providing some of the medicinal benefits of cannabis without the euphoria.[53][54] The researchers said the cannabis plant, enriched with CBD, "can be used for treating diseases like rheumatoid arthritis, colitis, liver inflammation, heart disease and diabetes". Research on CBD enhanced cannabis began in 2009, resulting in Avidekel, a cannabis strain that contains 15.8% CBD and less than 1% THC. Raphael Mechoulam, leading cannabinoid researcher, noted "It is possible that (Avidekel's) CBD to THC ratio is the highest among medical marijuana companies in the world, but the industry is not very organized, so one cannot keep exact track of what each company is doing".[55]

One wonders if all of the people on the internet arguing so vociferously for marijuana legalization based on its medicinal qualities would still support legalization if only the high-CBD strains were allowed.

From Project CBD:

Cannabidiol (CBD) is a compound in cannabis that has medical effects but does not make people feel “stoned” and can actually counter the psychoactive effects of THC. After decades in which only high-THC Cannabis was available, CBD-rich strains are now being grown by and for medical users.  

The reduced psychoactivity of CBD-rich cannabis makes it an appealing treatment option for patients seeking anti-inflammatory, anti-pain, anti-anxiety, and anti-psychotic effects without disconcerting lethargy or dysphoria.

Scientific studies underscore CBD’s potential as a treatment for many conditions, including chronic pain, diabetes, cancer, cardiovascular disease, alcoholism, PTSD, schizophrenia, antibiotic-resistant infections, rheumatoid arthritis, MS, epilepsy, and other neurological disorders. 

There is significant scientific evidence that THC has some seriously negative effects on the human brain. The results from a 2008 study in the British Journal of Psychiatry compared THC only, THC+CBD, and no cannabis found clear differences in levels of delusions and anhedonia:

Our results show higher levels of unusual experiences – an analogue of hallucinations and delusions – in individuals who had evidence of only Δ9-THC in their hair compared with those with both Δ9-THC and CBD, and those with no cannabinoid. There were also greater levels of delusions in this THC only group compared with individuals who showed no evidence of cannabinoids in their hair, with a similar trend in the THC+CBD group. The THC+CBD group reported less anhedonia than the other two groups.

A 2012 study in Psychological Medicine reached similar conclusions:

CBD attenuates the psychotic-like effects of cannabis over time in recreational users. Higher THC negatively impacts on memory and psychological well-being. These findings raise concerns for the harms stemming from use of varieties such as ‘skunk’ (sensimillia), which lack any CBD but currently dominate the supply of cannabis in many countries.

A 2012 study published in the Proceedings of the National Academy of Sciences found that ongoing marijuana use compromised cognitive functions across a the whole spectrum, including memory and intelligence. They also found that subjects who showed marijuana dependence by age 18 suffered greater IQ losses than those who did not. Here is the abstract:

Recent reports show that fewer adolescents believe that regular cannabis use is harmful to health. Concomitantly, adolescents are initiating cannabis use at younger ages, and more adolescents are using cannabis on a daily basis. The purpose of the present study was to test the association between persistent cannabis use and neuropsychological decline and determine whether decline is concentrated among adolescent-onset cannabis users. Participants were members of the Dunedin Study, a prospective study of a birth cohort of 1,037 individuals followed from birth (1972/1973) to age 38 y. Cannabis use was ascertained in interviews at ages 18, 21, 26, 32, and 38 y. Neuropsychological testing was conducted at age 13 y, before initiation of cannabis use, and again at age 38 y, after a pattern of persistent cannabis use had developed. Persistent cannabis use was associated with neuropsychological decline broadly across domains of functioning, even after controlling for years of education. Informants also reported noticing more cognitive problems for persistent cannabis users. Impairment was concentrated among adolescent-onset cannabis users, with more persistent use associated with greater decline. Further, cessation of cannabis use did not fully restore neuropsychological functioning among adolescent-onset cannabis users. Findings are suggestive of a neurotoxic effect of cannabis on the adolescent brain and highlight the importance of prevention and policy efforts targeting adolescents.

The negative impact of cannabis use on young people is not unexpected. The adolescent and teen years are the second most important period of brain development in a person's life (after infancy). It is also not surprising then that cannabis use in kids and teens doubles the risk for psychosis and schizophrenia - Dialogues in Clinical Neuroscience, 2005.

The authors in the above study suggest that cannabis is not solely responsible for the higher rates of serious mental illness. They argue that young people with premorbid symptoms of future psychosis are much more likely to self-medicate with marijuana.

It's clear based on the information above that THC is the likely culprit in memory loss, IQ decline, and increased risk of mental illness. With this understanding, legalization of marijuana should be predicated on the production and sale of high-CBD strains with little or no THC.

Here is a recent article from The Guardian (UK) that suggests people are finally starting to understand that the benefits of marijuana are found in the CBD and not in the THC.

Cannabis and memory loss: dude, where's my CBD?

Legalisation presents an opportunity to promote cannabis rich in a chemical that protects against its negative effects

Dude, Where's My Car? CBD in cannabis is thought to protect against dependence, psychotic symptoms … and memory loss. Photograph: Sportsphoto/Allstar/Cinetext
It isn't often that science and pop culture overlap, but the two fields are in agreement when it comes to the familiar trope of the forgetful stoner.

A recent study published in Schizophrenia Bulletin is the latest to reveal the detrimental effects that cannabis can have on memory. The authors report that people dependent on the drug – both healthy individuals and patients with schizophrenia – show impairments in memory compared with healthy volunteers and non-smoking schizophrenia patients.

Even more striking, the cannabis-using groups had significant decreases in the volume of two brain areas that are important for processing rewards, learning and working memory – the thalamus and striatum – and these changes were linked to their memory problems. There was no evidence to connect cannabis use and schizophrenia – the authors simply compare the two groups. However, previous studies have found a higher prevalence of psychosis among regular cannabis smokers.

Reports of memory loss with long-term cannabis use are nothing new, and an influential paper published last year provided evidence that smoking marijuana has a deleterious effect on intelligence. In the investigation, the cognitive abilities of participants were tested several times over the course of 25 years. The researchers found that heavy cannabis users had significant decreases in intelligence and memory ability as they aged, not only compared with non-smokers, but also compared with their younger selves. Additionally, the earlier they started smoking pot, the bigger the cognitive decline.

Obviously these findings are worrying, especially given the recent spate of cannabis legalisations in states across the US and in countries such as Uruguay. However, before we all start worrying about the good people of Colorado and Washington, it might be helpful to look closer at what's actually in the cannabis we're smoking nowadays, and what ingredients are contributing to these cognitive deficits.

THC (tetrahydrocannabinol) is the primary psychoactive compound in cannabis and is what causes the subjective "high". This includes changes in perceptual sensations, a feeling of contentedness and increased appetite. However, THC is also linked to many of the potential negative consequences of cannabis use, such as dependence, psychotic symptoms, and impaired memory and cognition.

Another important component, CBD (cannabidiol, which works by increasing natural cannabinoid levels in the brain) is associated with the calming, anti-anxiety effects of the drug. In addition, CBD is thought to protect against many of the potential negative effects of marijuana, including dependence, psychotic symptoms and cognitive impairments.

The THC concentration in cannabis has increased by as much as 12% over the past 30 years, making the drug much stronger than it used to be. At the same time, there has been a significant depletion of CBD, sometimes to levels as low as 0.1%. "Skunk", as this new strain of high-THC/low-CBD marijuana is called, is flooding the illegal marijuana market, and it is this variety that is thought to be behind the rise in cannabis dependence diagnoses, links to schizophrenia, and cognitive deficits seen over the past decade.

The changing chemical make-up of cannabis appears to be partly accidental and partly deliberate. New strains are often bred to have higher levels of THC in them, increasing the drug's potency. However, modern growing techniques have also affected these chemical levels. For example, illegal growers have turned to indoor marijuana farms to avoid detection. Growing cannabis locally in such farms also circumvents the need to import the drug, and guarantees a more reliable harvest. However, the 24-hour lighting used in these farms inadvertently reduces CBD levels in the plant. Thus, these new strains are not only bred for higher potency, with elevated THC content, they are also lacking the protection provided by CBD against the drug's negative effects.

It should be noted that the majority of research into cognitive deficits and cannabis use has focused on heavy or dependent users, and there's little evidence that occasional smokers show any of the problems mentioned above. But with the recent changes in drug policy, the chances are that more people will be smoking cannabis than ever before, and the more potent and more popular high-THC/low-CBD marijuana that is available today will increase their risk of dependence.

The recent legalisation of recreational and medicinal marijuana in parts of the US has the potential to reduce significantly the harms caused through incarceration or criminal records for minor drug-related offences. However, it also provides an opportunity to reduce the cognitive and psychiatric harms linked to cannabis use. With this shift in drug policy, it is now possible for states to monitor the commercial production of cannabis, regulating the levels of THC and CBD present in the drug. To facilitate this, they could force growers to use strains with higher levels of CBD, and revert to more old-fashioned farming methods that don't use round-the-clock lighting.

These changes could help protect individuals from the damaging effects of the drug, prevent the development of dependence in new users, and maybe even help our favorite Hollywood stoners remember where they left their car.