Anecdotal and increasingly scientific accounts of cannabinoid use have consistently highlighted the ways that it can affect the memory. This paper reviews the current extent of knowledge (as of 2017) in terms of the endocannabinoid system and its role in and effect on memory and learning.
This study looks mainly at the cannabinoid receptor type 1 (CB1), which is primarily found in the central nervous system (CNS). The other major cannabinoid receptor, CB2, is mostly found in the immune system and other tissues but also in the brain, where it plays a vital role.
Here is the full scientific article if you wish to download it.
The mechanisms of memory are still poorly understood but slowly the evidence is emerging for how the brain encodes and accesses memories. It almost certainly involves the endocannabinoid system, which is described here in some detail. The ECS seems to be involved in different phases of memory formation, recall, and extinction through both receptor-mediated and non-receptor mediated signalling. How, how much, and when cannabinoids are administered can change their effects.
Both the CB1 and CB2 receptors are expressed in the brain but in different areas. When CB1 or CB2 “blockades” are implemented, inhibiting the receptors from working, animal studies have shown that essential memory functions like fear acquisition, memory consolidation, recall, and conditioning are impaired.
This suggests that the endocannabinoid system is very important in memory systems overall. The advantage of this set up to clinicians is obvious: by using cannabinoids, memories can be extinguished or improved. Somewhat contradictory evidence shows that cannabinoid administration can help to extinguish memories in some conditions and aid their consolidation in others. Mostly CB1 agonists were used to investigating this effect and there are still many questions to be answered.
The individual role of CB1 and CB2 receptors in memory is a long way from being understood. Each seems to mediate different effects on memories in different ways and this is difficult to unravel. As interacting with one can cause cascades that affect the other, or more, different influences are made possible by interacting with other, newly discovered cannabinoid receptors, there has to be a lot of work undertaken before this will be clear.
The clear behaviour-altering effects of cannabinoids administered in the animal studies, and the subsequent understanding of the mechanisms involved, is hopeful for therapeutic applications. Fear and traumatic memory (PTSD) extinction mediated by relatively safe drugs like cannabinoids would be a boon to therapists trying to treat post-traumatic stress disorder.
The state of endocannabinoid science in memory is one of confusion. The fundamental processes of memory are only just being discovered and the role the endocannabinoid system plays is at once clear from a distance and hidden from view up-close. Clearly, cannabinoids can affect memory, and some of the mechanisms involved are partially understood, but the overall picture of how and why the effects emerge is still yet to be discovered and described.
The more we understand about the ECS, the more we appreciate its delicate complexity and usefulness. It is involved in many different processes, now we know more about how it works in the memory. As usual for cannabinoid research, more research is needed.