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A new cannabis study by a team or European researchers concludes that there is an urgent need to educate the public, health professionals, and policymakers about the risks involved with using high potency marijuana, also known as "skunk."
According to the scientists from King's College London and Sapienza University of Rome, “skunk-like” cannabis can damage the white matter nerve fibers responsible for communication between the two brain hemispheres of the cerebrum (Latin for "brain"). This is the first research to examine the specific effects of cannabis potency on brain structure.
The November 2015 study, “High Potency Cannabis Affects Corpus Callosum (CC) Microstructural Organization,” was published in the journal Psychological Medicine.
In a February 2015 study, published in Lancet Psychiatry, researchers found that the risk of someone having a psychotic disorder was three-times higher in users of skunk-like cannabis compared with a person who had never used cannabis. In a press release, Robin Murray, professor of psychiatric research at King's College, said, "This paper suggests that we could prevent almost one quarter of cases of psychosis if no one smoked high potency cannabis."
Amounts of THC in Marijuana Have Skyrocketed
The marijuana that my friends and I smoked in the 1980s was low potency compared to the majority of cannabis being sold today. Before the 1990s, the percentage of tetrahydrocannabinol (THC)—which is the psychoactive ingredient in marijuana that makes you feel high—was generally around 8 percent.
Today, “skunk farming” methods have created strains of cannabis with THC levels around 30 percent. The THC content of cannabis has tripled in some strains because producers have been cross-breeding various strains of cannabis over the years to meet user demands for high potency marijuana.
Since his home state legalized marijuana, Andy LaFrate, Ph.D., and colleagues in his Colorado lab have been testing various marijuana samples. "As far as potency goes, it's been surprising how strong a lot of the marijuana is," LaFrate says. "We've seen potency values close to 30 percent THC, which is huge." LaFrate is the president and director of research of Charas Scientific, one of eight labs certified by Colorado to do potency testing.
In addition to potency, LaFrate has observed alarmingly lower amounts of a substance called cannabidiol (CBD). The lack of CBD in skunk-like weed may be a contributing factor to why it's both potent and harmful. Research suggests that CBD can act as an antidote to THC and counteract psychotic side effects. Thus, it appears that cross-breeding marijuana strains creates a double whammy of psychological and medical risks by lowering CBD and increasing THC.
White Matter Integrity Is Linked to Cognitive Flexibility
For the recent European study, the researchers used Diffusion Tensor Imaging (DTI) to examine white matter in the brains of 56 patients who had reported a first episode of psychosis, as well as 43 healthy participants from the local community.
The researchers were specifically interested in examining the corpus callosum, which is the largest white matter structure in the brain and connects both hemispheres of the cerebrum. White matter consists of large bundles of nerve fibers that connect the gray matter from different regions of the brain and enables communication throughout the brain.
The corpus callosum is also loaded with cannabinoid receptors. THC binds with these receptors to make people feel high. The researchers found the higher the potency of cannabis—and the more frequent the use—the more significant the damage was to someone's white matter structures.
On the opposite end of the spectrum, a wide range of studies by Art Kramer and his colleagues at the University of Illinois at Urbana-Champaign have found that aerobic physical activity and cardiorespiratory fitness improves the integrity of white matter and brain connectivity. Recently, I wrote about this in a Psychology Today blog post, "Why Does Physical Activity Improve Cognitive Flexibility?"
Endocannabinoids and Runner's High May Also Improve Brain Connectivity
As a personal testimonial, I stopped smoking pot when I was 17 and discovered running. I can attest to the profound benefits of substituting the THC you get from cannabis with the self-produced endocannabinoids created through aerobic activity.
A few years ago, I did take a hit of high potency marijuana, just to see what it was like. One hit instantly took me "one toke over the line." It blew my mind how intensely skunk-like weed changed my perceptions of reality. Personally, I hated how "out there" and trippy it made me feel. Smoking high potency marijuana triggered flashbacks to a traumatic 'bad trip' I had on psilocybin as a teenager. I describe my harrowing experience with psychadelic drugs on p. 7 of The Athlete's Way,
"I don't know if you've ever had a bad trip, but it feels like all the tumblers in your brain are turning and reconfiguring, unlocking doors that should stay shut, closing windows that should stay open, all the while re-etching the blueprints of your psyche and the foundation of your soul, fusing your synapses into new configurations, permanently rearranging the architecture of your mind."
Although I wrote that passage over a decade ago, the latest study from King's College confirms the ability of high potency cannabis to disrupt the functional and structural architecture of your corpus callosum and brain.
A 2013 Psychology Today blog post I wrote, “Einstein’s Genius Linked to Well-Connected Brain Hemispheres,” was based on research which found that Albert Einstein had more extensive white matter connections between certain parts of his cerebral hemispheres compared to both younger and older control groups. The study, "The Corpus Callosum of Albert Einstein's Brain: Another Clue to His High Intelligence," was published in the journal Brain.
Taken together, these findings illustrate the importance of maintaining whte matter integrity of your corpus callosum. The good news is, making the decision to exercise regularly and create a natural runner's high by producing endocannabinoids will improve white matter brain connectivity.
Conclusions: High Potency Cannabis Can Damage Your Corpus Callosum
Anytime I write a Psychology Today blog post about the potential harms of cannabis, it evokes a passionate response from readers on both sides of the aisle. Many states across the United States are currently deciding whether or not to legalize marijuana. The debate about the pros and cons of marijuana can be heated.
Clearly, medical marijuana has some tremendous benefits. Personally, I believe that casual use of marijuana is probably less dangerous than alcohol. However, there appears to be a misconception that marijuana is harmless, and may in fact be, "healthy" for you.
As a public health advocate, I feel an obligation to convey the latest research findings, which show that frequent use of high potency cannabis significantly affects the white matter microstructures of the corpus callosum, regardless of the presence of a psychotic disorder. Given the increased availability and use of high potency cannabis, raising awareness about some of marijuana's detrimental effects is imperative.
In a press release, the European team of researchers conclude:
"There is an urgent need to educate health professionals, the public and policymakers about the risks involved with cannabis use. As we have suggested previously, when assessing cannabis use it is extremely important to gather information on how often and what type of cannabis is being used. These details can help quantify the risk of mental health problems and increase awareness on the type of damage these substances can do to the brain.”
As dangerous as alcohol is, the molecule itself is easy to regulate in both the manufacturing process and as a consumer. Based on the percentage of alcohol labeled on a bottle of wine, beer, or liquor it's easy to calculate how much alcohol you are consuming. This is not the case in terms of being able to gauge the potency of cannabis products.
Future research should lead to a better understanding of how increased THC levels combined with less CBD affects the impact of high potency cannabis on the human brain. Obviously, this research and applications are in their infancy. Hopefully, these recent findings will be a catalyst for more studies on the ever-changing nature of cannabis.
If you’d like to read more on this topic, check out my Psychology Today blog posts,
- "Why Have Marijuana Usage Disorders Doubled in the Past Decade?"
- "Heavy Marijuana Use Alters Teenage Brain Structure"
- "Why Is the Teen Brain So Vulnerable?"
- "Just Say No 2.0"
- "Why Are Marijuana Users Susceptible to Memory Distortion?"
- "Casual Marijuana Use Linked to Brain Changes in Young Adults"
- "Why Do Teens Assume Vaping or Smoking Marijuana Is Harmless?"
- "Cannabis Addiction Is Linked to Higher Levels of Cortisol"
- "Cannabis Targets Receptors in the Amygdala Linked to Anxiety"
- "Does Long-Term Cannabis Use Stifle Motivation?"
- "Is Runner's High Our Evolutionary Antidote for Laziness?"
© 2015 Christopher Bergland. All rights reserved.
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