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CBD Enhances Episodic Memory, Study Finds

By Alexander Beadle

Published: Sep 28, 2021   
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Taking CBD can improve a person’s verbal episodic memory, according to new research by scientists at the University of Basel, Switzerland.

Published in the Journal of Psychiatric Research, the scientists also found that this short-term improvement in verbal episodic memory (the ability to remember a series of words) while taking CBD was not accompanied by any deficit in attention or working memory performance.

The researchers believe that these findings demonstrate a potential therapeutic application for CBD in tackling episodic memory deficits in disorders such as Alzheimer’s disease or schizophrenia, which are hallmarked by poor episodic memory performance. However, they note that more research into the dose-response and time-response relationships for CBD’s effect on memory still needs to be done before CBD can be recommended clinically.

Participants perform better at verbal memory tasks after using CBD

In this double-blind, placebo-controlled, randomized crossover trial, participants were asked to complete a short sociodemographic and mental health questionnaire, followed by several questions about their current physical health, including their sleep duration and any potential drug or alcohol consumption on the day prior to their participation. In total, more than 30 participants were involved in the trial.

The participants were each given three series of five unrelated nouns to learn and immediately recall. This recall acted as a control to make sure that every participant had paid attention to the sequence. Immediately after this task, the participants vaped either a scented placebo oil or 12.5 mg of CBD oil under the supervision of a trial data collector for 15 minutes. In total each participant attended two sessions, one where they vaped the placebo oil and the other the CBD.

After this observed vaping period was over, the participants underwent a verbal episodic memory performance assessment, which was a free recall task conducted 20 minutes after the initial word-learning task. Here, participants were asked to write down all the words they could remember from the initial set of fifteen they were given to learn at the start of the trial session.

The researchers found that participants could recall 10 percent more words in the verbal episodic memory task after vaping CBD compared to the placebo.

After additional analysis to control for possible confounders – such as depression, frequency of cannabis use, mood, and body mass index (BMI) – the researchers found that this memory-enhancing effect of the CBD was independent of all other covariates, except for BMI.

“The effect of CBD on episodic memory was independent of age, sex, depressive symptoms, frequency of cannabis consumption in a year, and the ratings after vaping (relaxation, tiredness, motivation, mood, tolerance). However, the effect was not independent of BMI,” the researchers wrote.

“The interaction between BMI and drug suggests that the dose for subjects with lower BMI might have been too high to increase memory.”

The scientists suggest that the relationship between CBD dose and its beneficial effect on episodic memory might follow an inverted-U-shape curve – as seen with CBD and anxiety – rather than a linear relationship. With these questions regarding dosing and a potential association with BMI, the researchers recommend that more research must be done to investigate the dose-response relationship between CBD and memory.

CBD does not influence attention or working memory

Shortly before the verbal episodic memory recall assessment, each participant was also asked to complete two additional tasks designed to assess attention and working memory. By including these assessments, the researchers sought to establish whether CBD consumption might affect other aspects of cognitive function aside from episodic memory.

The first task, a standard “0-back” task to assess attention, asked the participants to react as quickly as possible to the appearance of a target picture in a sequence. A “2-back” task assessing working memory followed, where the participants were asked to judge whether a picture they were shown was a match to the one presented two slides before.

Over these two assessments, the researchers did not detect any significant differences between the CBD and placebo sessions. As the researchers wrote in their paper, this suggests that “CBD has no negative impact on these basic cognitive functions” and could thus be a promising therapeutic treatment for episodic memory problems. Specifically, the researchers suggest that CBD could possibly be applied to improve episodic memory impairments associated with certain psychiatric disorders, neurodegenerative disorders (such as Alzheimer’s disease), or stress and stress-related exhaustion.

The researchers do note several limitations with this study. Firstly, these results were based on a single administration of CBD and so it cannot be assumed that this would hold for repeated use. A similar trial involving both healthy participants and participants with relevant episodic memory deficits would also be beneficial, they say, as this trial only included the former.

“We would like to stress that we assessed acute effects of CBD on episodic memory 20 [minutes] after encoding, thus preventing any conclusions about CBD effects on memory consolidation,” they added.

“Therefore, besides the unknown dose-response relationship and that the results cannot be generalized to other types of CBD administration, further studies are needed to investigate isolated effects of CBD on the distinct memory phases of consolidation and retrieval.”

While further dose-response and time-response relationship studies will be needed, the researchers say this new work still demonstrates the ability of CBD to improve episodic memory and indicates a possible therapeutic potential for the cannabinoid.


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