Some of the side effects of delta 9 tetrahydrocannabinol (THC) are impaired short and long-term memory. Does caffeine prevent memory loss from THC — reduce the adverse effects?
Type of memories affected by THC
Episodic memory is considered by man to be the longterm memory while working memory is seen as short-term memory. The common opinion is that caffeine enhances memory. However, the question is: Does Caffeine Prevent Memory Loss From THC? Seemingly, the answer is “YES”, though, it is dependent on the memory type in question.
Caffeine from chemistry and pharmacology point of view
Caffeine is a purine alkaloid found in coffee beans, tea leaves, Ilex paraguariensis leaves. The popular Mate, Cola acuminata plant seeds or Paullinia cupana (Latin name guarana).
Caffeine has the strongest effect on the central nervous system from methylxanthines (also included in this group are theobromine from cocoa seeds and theophylline obtained from tea leaves). Caffeine effects are exerted by way of a neuromodulator known as adenosine.
Adenosine has four receptors: A1, A2A, A2B, and A3. Caffeine is an antagonist of all of them. For example, adenosine, as a receptor agonist, causes drowsiness, while caffeine, on the contrary, causes insomnia and increases alertness, blocking the action of adenosine. Below is a drawing showing the structure of both compounds:
Source: Caffeine – An Updated Series (Part II), Talayna Tremblay
Influence of caffeine on long-term memory
Let’s first look at the influence of caffeine on long-term memory. A study conducted in 2017 investigated how blocking of a particular adenosine receptor could reverse the episodic memory deficiency in mice. To this end, the substance WIN 55,212-2 was tested, which is a CB1 receptor agonist that works in a similar way to THC.
The mice were allowed to examine the subject, followed by the CB1 receptor agonist. The next day, the mice were tested to see if they could remember yesterday’s object. As expected, the CB1 agonist appeared to interfere with the memory of the mouse with respect to the object. The researchers then administered the adenosine A 2A receptor antagonist (daily for 30 days and a single dose administered at the same time as THC).
Caffeine also blocks adenosine A2A receptor, so you can expect to receive similar effects after its use.
How about short-term memory?
Unfortunately, caffeine can heighten short-term memory. The 2011 study showed the effects of THC and caffeine on working memory (short-term) in rats. The short-term memory in rats was significantly increased by THC in a dose-dependent manner (this means that higher THC doses resulted in an intense effect on memory). This wasn’t surprising though, because such results were seen earlier in both rodents and humans.
Caffeine vs low THC
Rodents that received a high concentration of THC, caffeine didn’t have any effect on them. This means, it neither enhanced nor worsen their working memory. However, when caffeine was mixed with a low dose of THC, short-term memory worsened. In other words, combining caffeine to THC (in low dose) impacts negatively on short-term memory performance.
The deterioration memory caused as a result of the combination of low THC can be likened to the rats that receive a high dose of THC.
This caffeine-impairing effect was simulated by the adenosine A1 receptor antagonist, not the adenosine A2A antagonist. This proves that the adenosine receptor A1, which is less able to cope with short-term memory, differs from the adenosine receptor A2, which improves long-term memory.
In conclusion, caffeine prevents the long-term memory loss induced by THC, but consuming caffeine and THC (in low dose) at the same time may have an adverse effect on working memory — the short-terms memory.