As researchers dig ever deeper into the cognitive effects of cannabis, the need to study the interactions between different cannabinoids – rather than looking at each component individually – is becoming increasingly apparent. Often referred to as the entourage effect, the combined action of the various ingredients of marijuana has a modulating effect on the properties of certain key cannabinoids, with major implications for the overall health and safety profile of different chemovars.
For instance, the interplay between tetrahydrocannabinol (THC) and cannabidiol (CBD) has been found to significantly alter the cognitive impact of cannabis. In particular, the ratio of these two cannabinoids appears to massively affect the degree of temporary memory impairment that users experience while stoned.
CBD Restores Memory While High
A new study in the Journal of Cannabis Research[i] documents the recall abilities of regular cannabis users while under the influence of their preferred marijuana strains and products, in order to determine how this is influenced by interaction between CBD and THC. Participants were asked to complete a verbal recognition memory tests before self-administering their own cannabis, using whichever mode of administration they chose. Researchers then monitored levels of both THC and CBD in participants’ blood as they took the memory test for a second time.
Results indicated that those who used cannabis products containing predominantly THC tended to perform worse on the memory test once they were high, but that those who used products consisting mostly of CBD did not. This was reflected in their blood cannabinoid levels, with participants’ performance dropping most dramatically as their THC levels peaked.
More importantly, however, those who used cannabis containing both THC and CBD displayed no memory impairment, which suggests that the presence of CBD somehow nullifies the memory loss that occurs under the influence of THC.
Significantly, this is far from the first study to indicate that the CBD has a protective effect on memory, and can attenuate the impact of THC. For instance, a key paper in the British Journal of Psychiatry showed that the concentration of CBD in cannabis is negatively correlated with memory impairment, regardless of the THC content[ii].
CBD Protects Various Aspects Of Cognition
The restorative potential of CBD is not limited to memory, with several previous studies highlighting its ability to attenuate many of the other elements of the stoned experience. One research paper even revealed that increasing the CBD content of cannabis can eliminate the munchies by decreasing the temptation to eat while high[iii].
In another study, researchers gave volunteers either 600 milligrams of CBD or a placebo, before administering intra-venous THC. Those that had received CBD displayed lower levels of paranoia and improved memory performance, suggesting that this cannabinoid undoes many of the acute properties of THC[iv].
How Does CBD Produce These Effects?
Much more research is needed in order to elucidate the mechanisms by which CBD produces its neuroprotective effects, although scientists have made a pretty decent start. For example, memory loss is often associated with increased inflammation in the hippocampus, and several studies have revealed that CBD protects against this by inhibiting the release of inflammatory proteins throughout the brain[v].
The antioxidative properties of CBD have also been highlighted as a potential mode of action, as oxidative stress in the brain is known to cause a deterioration in cognition. Studies on mice have shown that CBD reduces oxidative damage in certain key brain regions, which may be crucial to its neuroprotective capacity.
Finally, CBD has been associated with an increase in brain-derived neurotrophic factor (BDNF) in the hippocampus, which facilitates the growth and maintenance of neurons in this vital brain region. It’s worth mentioning that THC has also been shown to convey numerous advantages, such as protecting against certain types of cancer. However, it is becoming increasingly clear that the full benefits of cannabis are likely to depend on the entourage effect, as the various components of marijuana work together to produce an array of positive outcomes.
[i] Curran T, Devillez H, YorkWilliams SL, Bidwell LC. Acute effects of naturalistic THC vs. CBD use on recognition memory: a preliminary study. Journal of Cannabis Research. 2020 Dec;2(1):1-2. – https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-020-00034-0
[ii] Morgan CJ, Schafer G, Freeman TP, Curran HV. Impact of cannabidiol on the acute memory and psychotomimetic effects of smoked cannabis: naturalistic study. The British Journal of Psychiatry. 2010 Oct;197(4):285-90. – https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/impact-of-cannabidiol-on-the-acute-memory-and-psychotomimetic-effects-of-smoked-cannabis-naturalistic-study/54EB46D7698008BA4A9E5A27A57AA281
[iii] Morgan CJ, Freeman TP, Schafer GL, Curran HV. Cannabidiol attenuates the appetitive effects of Δ 9-tetrahydrocannabinol in humans smoking their chosen cannabis. Neuropsychopharmacology. 2010 Aug;35(9):1879-85. – https://www.nature.com/articles/npp201058
[iv] Englund A, Morrison PD, Nottage J, Hague D, Kane F, Bonaccorso S, Stone JM, Reichenberg A, Brenneisen R, Holt D, Feilding A. Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment. Journal of psychopharmacology. 2013 Jan;27(1):19-27. – https://journals.sagepub.com/doi/10.1177/0269881112460109
[v] Osborne AL, Solowij N, Weston-Green K. A systematic review of the effect of cannabidiol on cognitive function: Relevance to schizophrenia. Neuroscience & Biobehavioral Reviews. 2017 Jan 1;72:310-24. – https://www.sciencedirect.com/science/article/abs/pii/S0149763416304390?via%3Dihub