# CBD's Impact on THC: New Insights from Recent Research
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Understanding Cannabis Varieties
A few years back, I stepped into a licensed cannabis dispensary in Massachusetts, driven by curiosity about the buzz surrounding cannabis. As I stood there, somewhat clueless, a friendly budtender began to explain the nuances between various marijuana strains. Some strains, like Acapulco Gold, are uplifting and invigorating, while others, such as Purple Kush, promote relaxation and sleepiness. Each strain seemed to evoke specific emotions or memories, akin to a sophisticated wine tasting experience. However, much like wine, the variations in marijuana can be perplexing and inconsistent.
It’s crucial to recognize that not all cannabis is identical. While delta-9-tetrahydrocannabinol (THC) is the compound primarily responsible for the high, it’s not the sole ingredient in the plant. The second most significant component is cannabidiol (CBD), which many believe counteracts the anxiety-inducing effects of THC. This has led to the advice from dispensary staff to select strains with balanced CBD levels if one wishes to avoid THC's potential side effects.
Challenging Assumptions: New Research Findings
But is this conventional wisdom accurate? A fresh study published in JAMA Network Open presents findings that suggest the opposite may be true. This research, led by Dr. Austin Zamarripa and his team, sheds new light on the interaction between THC and CBD.
The study involved 18 adults who had refrained from cannabis use for at least a month. They participated in a trial that was undoubtedly more entertaining than the typical experiments conducted at my lab at Yale. In a randomized design, participants consumed specially prepared brownies on separate occasions, each spaced at least a week apart.
The first condition was a control brownie, the second contained 20mg of THC, and the third was infused with both 20mg of THC and 640mg of CBD. For context, 20mg of THC is approximately one-third of what one might find in a contemporary joint, although it’s nearly double the amount found in joints from the 1970s. As for the 640mg of CBD, it is considered a significant dose, with some individuals starting at 5mg per kilogram for therapeutic benefits.
Both THC and CBD interact with the liver's cytochrome P450 system, which plays a crucial role when ingested rather than smoked due to first-pass metabolism. Consequently, CBD may enhance the absorption of THC into the bloodstream when consumed together.
Examining the Outcomes
Now, let’s delve into the results. The blood concentration of THC revealed significant differences. When CBD was present, THC levels peaked faster, with nearly double the area under the curve compared to THC alone.
Participants reported a stronger “drug effect” when THC was combined with CBD. Interestingly, while the perceived pleasant effects remained relatively unchanged, the unpleasant effects increased significantly, indicating that CBD did not alleviate THC-induced anxiety; rather, it exacerbated it.
The cognitive performance of participants also suffered. Scores on tasks measuring cognitive abilities were notably worse when CBD was combined with THC. Furthermore, heart rates were elevated during the combined exposure to both compounds, contradicting the commonly held belief that CBD provides a calming effect.
Conclusion: Reevaluating CBD's Role
The findings are clear: CBD may amplify THC's effects when ingested, and not in a beneficial way. This could be due to CBD interfering with the enzymes responsible for metabolizing THC or possibly inhibiting those enzymes directly. Regardless of the mechanism, it is safe to conclude that the notion that CBD moderates THC's effects has been debunked.
This commentary was initially published on Medscape.com.