Researchers from University College London have discovered that a single dose of cannabidiol (CBD) significantly increases blood flow to the hippocampus, a part of the brain that plays an important role in memory and emotion. Publishing their work in the Journal of Psychopharmacology, the study authors explain that their findings could have major implications for the treatment of conditions such as Alzheimer’s disease and post-traumatic stress disorder[i].
Previously, scientists had discovered that CBD produces a number of positive effects in rat brains, such as stimulating the formation of new neurons[ii] and protecting brain cells from oxidative damage[iii]. Another pre-clinical study even found that the cannabinoid helps neurons to form more connective branches, which could help to enhance cognitive flexibility and facilitate recovery from mental health disorders[iv]. However, this is the first study to reveal a direct and immediate impact on cognition in the human brain following a single administration of CBD.
To conduct their research, the study authors recruited 15 people with little or no history of cannabis use, and gave them each 600 milligrams of CBD or a placebo on several occasions, always separated by at least a week. After each trial, the researchers measured blood flow to certain brain regions using a technique called arterial spin labelling.
Results showed that CBD significantly increased blood flow to the hippocampus, but not to other regions of the medial temporal lobe, of which the hippocampus is a part. This is significant as it suggests that CBD acts specifically on the hippocampus, and is therefore likely to have a notable effect on cognition and mental health.
For instance, higher hippocampal blood flow has been associated with improved memory, which is just one reason why this key brain region has become such an important therapeutic target for conditions such as dementia[v]. Its role in mood disorders like depression and PTSD has also been well established, and the fact that CBD produces an instant increase in blood flow to the hippocampus therefore provides compelling evidence for its therapeutic potential.
The study authors also noted an increase in blood flow to the orbitofrontal cortex following each dose of CBD. This is located within the prefrontal cortex, which controls higher-level cognitive functions such as planning and decision making. The implications of this finding are not yet clear, and future studies will be required in order to determine the full extent of the advantages that are associated with this increased blood flow.
While the benefits of CBD for cognition and mental health have been talked about for years, the kind of hard science that is needed to corroborate these claims had until now been lacking.
In a statement, lead author Dr Michael Bloomfield explained that “this is the first study to find that CBD increases blood flow to key regions involved in memory processing, particularly the hippocampus.[vi]”
“If replicated, these results could lead to further research across a range of conditions characterised by changes in how the brain processes memories, including Alzheimer’s disease, where there are defects in the control of blood control flow, along with schizophrenia and post-traumatic stress disorder.”
[i] Bloomfield MA, Green SF, Hindocha C, Yamamori Y, Yim JL, Jones AP, Walker HR, Tokarczuk P, Statton B, Howes OD, Curran HV. The effects of acute cannabidiol on cerebral blood flow and its relationship to memory: An arterial spin labelling magnetic resonance imaging study. Journal of Psychopharmacology. 2020 Aug 7:0269881120936419. – https://journals.sagepub.com/doi/10.1177/0269881120936419
[ii] Wolf SA, Bick-Sander A, Fabel K, Leal-Galicia P, Tauber S, Ramirez-Rodriguez G, Müller A, Melnik A, Waltinger TP, Ullrich O, Kempermann G. Research Cannabinoid receptor CB1 mediates baseline and activity-induced survival of new neurons in adult hippocampal neurogenesis. – https://www.researchgate.net/profile/Susanne_Wolf3/publication/44690236_Cannabinoid_receptor_CB1_mediates_baseline_and_activity-induced_survival_of_new_neurons_in_adult_hippocampal_neurogenesis_Cell_Commun_Signal/links/02bfe512e32a5bf4e1000000/Cannabinoid-receptor-CB1-mediates-baseline-and-activity-induced-survival-of-new-neurons-in-adult-hippocampal-neurogenesis-Cell-Commun-Signal.pdf
[iii] Hampson AJ, Grimaldi M, Axelrod J, Wink D. Cannabidiol and (−) Δ9-tetrahydrocannabinol are neuroprotective antioxidants. Proceedings of the National Academy of Sciences. 1998 Jul 7;95(14):8268-73. – https://www.pnas.org/content/95/14/8268.short
[iv] Campos AC, Fogaça MV, Scarante FF, Joca SR, Sales AJ, Gomes FV, Sonego AB, Rodrigues NS, Galve-Roperh I, Guimarães FS. Plastic and neuroprotective mechanisms involved in the therapeutic effects of cannabidiol in psychiatric disorders. Frontiers in pharmacology. 2017 May 23;8:269. – https://www.frontiersin.org/articles/10.3389/fphar.2017.00269/full?handl_url=https://successtms.com/blog/new-treatments-for-depression&handl_ip=126.96.36.199
[v] Heo S, Prakash RS, Voss MW, Erickson KI, Ouyang C, Sutton BP, Kramer AF. Resting hippocampal blood flow, spatial memory and aging. Brain research. 2010 Feb 22;1315:119-27. – https://www.sciencedirect.com/science/article/abs/pii/S0006899309026547