On caffeine and cannabis

The relationship between caffeine and cannabis and the effects on brain chemistry are examined in the Journal of Neuroscience

By Peter Chen

May 7, 2016

Coffee and cannabis go together like wine and cheese. So much so, that in the Netherlands, establishments where the sale and use of cannabis is permitted are customarily referred to as coffeehouses. Capitalizing on the relationship between cannabis and coffee, a Canadian company has even created cannabis infused coffee pods, allowing users to brew up a pot of coffee.

Anecdotal evidence abounds regarding the complementary nature of the two substances, but there is now scientific evidence that further substantiates this claim, and even provides insight into how brain chemistry is affected by the combination.

Caffeine is widely known as the world’s most used drug. Caffeine doesn’t simply inject your body with more energy as some may believe. Instead, caffeine works by blocking adenosine neurotransmitter receptors in your brain and prevents adenosine from activating receptors which can, in turn, cause fatigue.

This is to say that caffeine acts as a receptor antagonist and prevents fatigue rather than provide energy. Structural similarity between adenosine and caffeine is what enables caffeine to step in and block adenosine’s access to its own receptor. It is worth noting that these neurotransmitter receptors are present on both sides of the synapse. A synapse is the connection point between two neurons and is what allows a signal to be passed on to the next neuron. Think of a synapse as a crevasse between two glaciers with a bridge anchored to both sides of the gap; these represent pre- and post-synaptic receptors.

A study published in the Journal of Neuroscience used monkeys that were primed for addiction to delta-9-tetrahydrocannabinol (THC) (Justinova, Redhi, Goldberg, & Ferre, 2014). They were allowed to freely administer THC as much or as little as they’d like.

The study found that when a synthetic analogue compound responsible for blocking the pre-synaptic adenosine receptors was introduced, the monkeys stopped self-administering THC. In contrast, when the post-synaptic adenosine receptors were blocked by a different synthetic compound, the moneys increased self-administering of THC.

Caffeine, however, does not discriminate between post- and pre-synaptic adenosine receptors. The researchers used an adenosine receptor antagonist that behaves similar to caffeine called MSX-3. The results suggest that at low doses of caffeine, the monkeys decreased the amount of self-administered THC and at high doses of caffeine, the amount of self-administered THC increased.

The interpretation of the results from this study goes as follows. When a person is first exposed to coffee and caffeine, the effects of feeling energised and excited satisfy their needs and therefore they are less likely to over indulge in cannabis. As tolerance begins to build, each subsequent cup of coffee begins stimulating other parts of the brain, namely the endogenous endocannabinoid system. Therefore, at high doses of caffeine, cannabis reinforces the euphoria and enhances the effects of both substances but also makes cessation of coffee and cannabis consumption all the more difficult.

A few caveats remains to be explained. The results of the study were obtained from monkey test subjects and it is still not clear if the same effects occur in humans. The study also relates to cannabis addiction in that it provides insight into how it can be triggered and also countered with the use of adenosine receptor antagonists or coffee. Lastly, other studies have suggested that the mixture of these two substances can lead to cognitive impairments and memory loss.

While the two substances appear to be intrinsically linked, their relationship seems to increase dependence on both substances. Although the long term side effects of this in humans are still unclear, it should not discourage you from taking your coffee with sugar, cream and cannabis.

Works Cited

Justinova, Z., Redhi, G., Goldberg, S., & Ferre, S. (2014). Differential Effects of Presynaptic versus Postsynaptic Adenosine A2A Receptor Blockade on Δ9-Tetrahydrocannabinol (THC) Self-Administration in Squirrel Monkeys. The Journal of Neuroscience, 34(19): 6480-6484.