By Jenny Menzel, H.C.
New research investigating the possible influence of cannabidiol (CBD) on cerebral blood flow has recently been published in the Journal of Psychopharmacology, and the results may provide renewed hope for improving memory processing in conditions such as Alzheimer’s disease, schizophrenia, depression, and post-traumatic stress disorder (PTSD).
A Look at CBD and Its Impact on Memory
The primary aim of the study was to determine first whether CBD could indeed influence cerebral blood flow to the areas in the brain involved in memory processing, with a secondary aim to see whether a CBD influence could affect working and episodic memory — more commonly referred to as short-term memory and long-term memory, respectively.
To add clarity, working memory takes place in the frontal cortex and parietal lobe in the brain and is theorized to actually be two forms of distinct memory — allowing us not only to store short-term memory, but also to manipulate it. The hippocampus and temporal lobe in the brain are most important in episodic memory (EM) — our memories of events and experiences that usually carry an emotional charge, such as details of a car accident we were in, or happiness that accompanies the celebration of childbirth.
The double-blind, placebo-controlled study monitored 15 healthy subjects — nine females, six males — aged 18-70 with no history of cannabis or CBD use. Participants were given identical 600 mg pills to take orally, either CBD or placebo, on two separate occasions at least one week apart.
Three hours after administration, researchers measured the subjects’ cerebral blood flow with arterial spin labeling — a magnetic resonance imaging (MRI) brain scan technique used to measure oxygen and nutrient delivery to body tissue through the blood. Memory tasks were conducted roughly 1-3 hours after MRI scanning.
The Study Results
Results showed CBD significantly increased cerebral blood flow to the hippocampus, a part of the limbic system located in the medial temporal lobe (MTL). However, blood flow did not increase in the MTL surrounding the hippocampus.
While no differences were noted in memory task assessments, CBD did induce increased blood flow to the orbitofrontal cortex as well — an area of the brain located in the prefrontal cortex, just above the eye sockets, where emotional responses and decision making take place.
In an online interview with the study’s lead author, Dr. Bloomfield stated, “To our knowledge, this is the first study to find that CBD increases blood flow to key regions involved in memory processing, particularly the hippocampus.”
While there were major strengths in this study, such as the testing of CBD levels in plasma, double-blinding, and randomization of the CBD and placebo order — there were some limitations. The study only used single doses of CBD in healthy volunteers, limiting the ability to draw conclusions for repeated dosing or the use of CBD in subjects with cognitive disorders.
Even though further research is needed, CBD displayed acute memory-boosting effects — evidence of the ability to target specific brain regions had previously been disputed. This study lends hope to those suffering from conditions that result in cognitive decline.
- Bloomfield MAP, Green SF, Hindocha C, et al. The effects of acute cannabidiol on cerebral blood flow and its relationship to memory: An arterial spin labelling magnetic resonance imaging study. J Psychopharmacol. 2020;34(9):981-989. doi:10.1177/0269881120936419
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