Cognitive function of Cannabidiol: A boost to social learning?

A recent study by researchers at National Cheng Kung University in Taiwan, published in the journal Psychopharmacology, provides new evidence of how CBD can influence learning and memory in social contexts - at least in mice.

The researchers investigated whether CBD could enhance social learning by modulating acetylcholine, a neurotransmitter essential for attention and memory. Their focus was a behavioural task known as the socially transmitted food preference (STFP), which measures the extent to which mice learn about safe foods by interacting with peers that have already sampled them. This form of social learning is well-established in animal behaviour research and closely tied to memory mechanisms.

In a controlled experimental setting, male mice were given a single dose of CBD (20 mg/kg) 30 minutes before interacting with other mice that had consumed a flavoured food. The outcome was clear: CBD-treated mice more strongly preferred the same food flavour as their demonstrator peers—an indication of enhanced memory for the socially acquired information. This effect was present both immediately after the interaction and 24 hours later.

The researchers sought to determine whether this effect was linked to changes in acetylcholine signalling in the basal forebrain, a region of the brain involved in learning and memory. In follow-up experiments, they reduced levels of acetylcholinesterase, an enzyme that breaks down acetylcholine, and observed a similar memory enhancement.

Conversely, when they blocked muscarinic acetylcholine receptors with scopolamine, the memory-enhancing effect of CBD was eliminated. These results suggest that the observed cognitive benefits are dependent on muscarinic receptor activity in the cholinergic system.

Further analysis revealed that the correlation between acetylcholine levels in the basal forebrain and memory performance was specific to the CBD-treated group. Mice that responded to CBD with higher acetylcholine levels performed better on the memory task, while untreated mice showed no such correlation.

Importantly, the effects appeared to be specific to memory and not due to general changes in behaviour. CBD did not alter the mice’s locomotor activity, food consumption, or olfactory discrimination. While the compound reduced anxiety-like behaviour shortly after administration, this effect subsided by the time of the delayed memory test.

The findings support previous research that points to the significance of acetylcholine and the cholinergic system for social memory and the ability to learn from others, and suggest that a pharmacological increase in acetylcholine activity - either by inhibiting its breakdown or through CBD treatment - may improve social memory.

However, the researchers note several limitations. The experiments involved only one CBD dosage and were conducted exclusively in young male mice. It remains to be seen whether similar results would occur in females, older subjects, animals with cognitive impairments as well as with lower or higher doses of CBD. 

The heterogeneity in response to CBD also warrants further investigation. Not all CBD-treated mice displayed improved memory or elevated acetylcholine levels, which the researchers believe could have implications for personalised medicine. This means that CBD could improve the cognitive abilities of some individuals in clinical contexts, but have limited or no effect on others. This variability emphasises the opportunities for personalised approaches in therapeutic applications.

More broadly, the study contributes to a growing body of knowledge about the nuanced interactions between phytocannabinoids and neurochemical systems. The role of acetylcholine in socially mediated learning is further substantiated, and the work raises new questions about how CBD might be used to influence cognitive function - either in health or disease.

Further research is needed to understand more precisely how CBD affects cholinergic signalling and whether it acts directly on acetylcholine receptors or indirectly by altering enzyme activity. Other important aspects, such as whether these effects can be reproduced in animal models of cognitive disorders or in humans, also need to be investigated. Even if clinical implementation is still a long way off, studies such as these are important for more targeted research into the neurological effects of cannabinoids.