Background: Accumulating evidence suggests that the non-intoxicating cannabinoid compound cannabidiol (CBD) may have antipsychotic and anxiolytic properties, and thus may be a promising new agent in the treatment of psychotic and anxiety disorders. However, the neurobiological substrates underlying the potential therapeutic effects of CBD are still unclear. The aim of this systematic review is to provide a detailed and up-to-date systematic literature overview of neuroimaging studies that investigated the acute impact of CBD on human brain function. Methods: Papers published until May 2020 were included from PubMed following a comprehensive search strategy and pre-determined set of criteria for article selection. We included studies that examined the effects of CBD on brain function of healthy volunteers and individuals diagnosed with a psychiatric disorder, comprising both the effects of CBD alone as well as in direct comparison to those induced by ∆9-tetrahydrocannabinol (THC), the main psychoactive component of Cannabis. Results: One-ninety four studies were identified, of which 17 met inclusion criteria. All studies investigated the acute effects of CBD on brain function during resting state or in the context of cognitive tasks. In healthy volunteers, acute CBD enhanced fronto-striatal resting state connectivity, both compared to placebo and THC. Furthermore, CBD modulated brain activity and had opposite effects when compared to THC following task-specific patterns during various cognitive paradigms, such as emotional processing (fronto-temporal), verbal memory (fronto-striatal), response inhibition (fronto-limbic-striatal), and auditory/visual processing (temporo-occipital). In individuals at clinical high risk for psychosis and patients with established psychosis, acute CBD showed intermediate brain activity compared to placebo and healthy controls during cognitive task performance. CBD modulated resting limbic activity in subjects with anxiety and metabolite levels in patients with autism spectrum disorders. Conclusion: Neuroimaging studies have shown that acute CBD induces significant alterations in brain activity and connectivity patterns during resting state and performance of cognitive tasks in both healthy volunteers and patients with a psychiatric disorder. This included modulation of functional networks relevant for psychiatric disorders, possibly reflecting CBD’s therapeutic effects. Future studies should consider replication of findings and enlarge the inclusion of psychiatric patients, combining longer-term CBD treatment with neuroimaging assessments.
Copyright © 2021 Batalla, Bos, Postma and Bossong.
Conflict of interest statement
Keywords: Cannabis (marijuana); cannabidiol; delta9-tetrahydrocannabinol; functional MRI; neuroimaging.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
It is specifically CBD’s capacity to target the serotonin 1A receptor that offers the greatest range of possibilities. This ability could help CBD deal with disorders such as depression, neuropathic pain, and anxiety disorders. It could even help reduce opioid dependence. Given that opioids kill almost 1,000 people a week in the United States, CBD’s potential to reduce opioid usage makes it worth further examination.
The possible benefits attributed to both are down to their respective effects on the body’s endocannabinoid system (ECS). The ECS contains endocannabinoids, naturally produced cannabinoids, that bind to receptors located throughout the body. The ECS helps regulate various things such as appetite, pain, and memory.
In contrast, CBD has a significantly less potent effect on the ECS’s receptors. It only binds loosely to CB1 receptors. This action actually blocks the receptors, thus reducing the effects of THC.
How Do CBD Products Affect the Brain?
CBD is one of over 110 cannabinoids produced by cannabis. It is also abundant in the hemp plant. THC is famed for its ability to cause an intoxicating high. In contrast, CBD is non-intoxicating. Nonetheless, there is evidence that both compounds have possible therapeutic effects. This is part of the reason why CBD for sale is now an exciting proposition.
Unfortunately, an excessive level of free radicals could result in the loss of DNA particles. This is especially the case if the body doesn’t create enough antioxidants. This process is linked to medical conditions such as Parkinson’s and Alzheimer’s.
CBD’s impact on CB2 receptors may help reduce oxidative stress. Cannabidiol also appears to have antioxidant properties. According to a study published in the Journal of Alzheimer’s Disease in 2014, CBD products’ long-term usage led to antioxidative and anti-inflammatory effects.
The Neuropsychopharmacology journal published a relevant study in 2019. It analyzed the impact of CBD on brain excitation and inhibition systems. The researchers recruited 34 male volunteers, half of whom had autism spectrum disorder (ASD). They found that CBD potentially shifted GABA+ and Glx metabolites, which could help with some of the symptoms of ASD. However, the team pointed out that further studies were required.