A New Study Shows CBD and THC Act Differently
Summarize
A recent animal study investigated how CBD and THC act alone and together in the brain. The results found that THC acts across different brain regions by increasing cerebral blood flow, leading to hyperconnectivity of brain regions. CBD was found to have little effect on cerebral blood flow, suggesting the cannabinoid may calm neural activity across the brain regions. When THC and CBD were given together, the effects produced were not as strong for either cannabinoid.
CBD and THC Actions
A study published in the Journal of Psychopharmacology used neuroimaging of rat brains to compare how CBD and THC affect blood flow and communication in the brain. THC is known to cause a high by its interaction with the cannabinoid type 1 receptor (CB1) in the brain. CBD does not produce a high and acts differently in the body. CBD interacts with more than one system in the body, but it does not bind strongly to cannabinoid receptors.
The different actions in the body explain why the two cannabinoids are used for different medical reasons. THC is approved for medical use to treat several health conditions. A pharmaceutical-grade CBD form called Epidiolex is approved for certain disorders. It has also been shown to have anti-oxidant effects.
The Study
The animal study measured the effects of CBD and THC taken together. It is an animal study because of practical considerations associated with using human participants. For example, how would prior recreational drug use affect the controlled study’s results, and what are the ethical considerations?
The adult male rats were separated into four groups. Each group received either 10 mg/kg of THC, 150 mg/kg of CBD, a combination of THC and CBD in roughly equal amounts or a placebo. Two hours after dosing, magnetic resonance imaging was used to identify resting-state functional connectivity (activity across different brain regions) and blood flow in the brain. Measuring blood oxygenation patterns provides information on how the different brain regions communicate.
The results were as follows.
- Rats given only THC showed widespread increases in the connectivity between regions of the brain, while blood flow was significantly increased in many regions. There is an increase in the clustering and strength of connections.
- Rats given only CBD showed a general reduction in connectivity between brain regions and did not show significant changes to blood flow. This suggests that CBD may have a calming effect on the connectivity system in the brain.
- Rats given THC and CBD experienced elevated functional connectivity and cerebral blood flow compared to the placebo group, but not as much as the THC-only group experienced. CBD appeared to moderate some of THC’s effects on brain activity.
The study author, Diana Cash, an associate professor at King’s College London and director of The Brain Centre, explained,
“We found that THC strongly increased both brain connectivity and blood flow, while CBD had no effect on blood flow but significantly reduced connectivity. The combination produced an effect somewhat similar to THC, but much weaker, suggesting that CBD can dampen or modulate the effects of THC. This could help explain why traditional cannabis, which contains both compounds, is often reported to produce milder effects compared to newer strains bred for very high THC content.”
The researchers caution that there are some limitations to keep in mind concerning the findings. Since the study used rats, the results may not apply fully to humans. Also, people with medical conditions may respond differently to cannabis. In addition, it is not known if the use of anesthesia for imaging purposes interacts with cannabinoid signaling while not awake. Future research will add to the brain imaging profiles by testing how different cannabinoid doses and delivery methods, and other cannabis cannabinoids and compounds influence brain activity.
Corroborating Existing Knowledge
It is interesting to note that this research project supports prior projects’ findings that study participants experienced less of a high when taking THC and CBD together. There is also a large amount of anecdotal evidence. This study supports the potential therapeutic value of THC and CBD in the right circumstances. Though there is still so much to learn about the effects of THC and CBD on the brain and how interactions change when cannabinoids are combined, this is another study demonstrating the potential power of plant compounds to support human health and wellness.
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