By Harriet Milligan
In 2019, CBD started to gain a lot of traction both in the public sphere and medical communities. Products are popping up everywhere, from CBD balm in grocery stores to getting a CBD latte at your local coffee shop. There have been a lot of claims surrounding these products, but are they actually rooted in science?
Cannabidiol (CBD) is derived from the cannabis plant, which is known for causing a “high” specifically involving euphoria, heightened sensitivity to surroundings, and relaxation. CBD is the main compound in cannabis that is non-euphoric and non-addictive. Due to this, CBD has captured the attention of scientists who have found a number of promising effects, including analgesic, antipsychotic, antioxidant, anti-inflammatory, anticonvulsant effects among others (Blessing et al., 2015). The broad spectrum of positive effects on the body is due to CBD’s wide pharmacological profile, meaning it can act on a variety of different receptors in the body. For the sake of this article, we will focus specifically on its effects on the serotonin 5-HT1A receptor.
Serotonin 5-HT1A receptors are the target for many Generalized Anxiety Disorder treatments, as it has been shown that serotonin pathways play a role in both fear and anxiety. The mechanism by which CBD effects these receptors is uncertain . However, CBD is either a direct or indirect agonist, meaning it stimulates the receptor through binding directly or through another site or molecule (Blessing et al., 2015). Either way, since the 5-HT1A receptor has inhibitory effects, the CBD will decrease signaling from that receptor which is thought to induce the anxiolytic effects.
Preclinical and clinical data supports the claims of CBD being anxiolytic. A recent study on rats assessed the effects of CBD on the 5-HT receptors as well as anxiety-like behaviors (DeGregorio et al., 2019). Using in vivo single unit recordings (a tool used to measure the electrical activity of a single neuron), it was found that CBD significantly reduced firing activity of 5-HT neurons. They also found a reduction in anxiety like behavior on the elevated plus maze, which is a common behavioral paradigm used to assess anxiety in rats and mice (DeGregorio et al., 2019). These findings are promising for the understanding of the mechanism of CBD in anxiety behaviors in rats, but the reaction in humans could be different.
Recently, the anxiolytic effects of CBD were shown in humans, by measuring anxiety during public speaking (Linares et al., 2019). Healthy male participants received 150, 300, or 600 mg of CBD or a placebo in this double-blind experiment. The participants then went through a simulated public speaking test, which is well established as an anxiety inducing test. During the test, participants were rated on the Visual Analogue Mood Scale (VMAS) and physiological measures including heart rate and blood pressure. VMAS is completed by the participant; they are asked to rate their mental state based on a scale between two opposite moods (for example calm versus excited) for 16 different items. They found that the 300 mg of CBD lowered VMAS scores (meaning the participant was less anxious). In conjunction with studies on rat models, this experiment shows the promising effects of CBD on anxiety disorders in humans.
You may ask, is this enough research to support the claims surrounding CBD in the public sphere? In short, no; there is always more research to be done to completely understand the pharmacological effects of a substance. However, there is a growing body of science to support the hype around CBD’s anxiolytic effects. This basis can be expanded upon to understand the effect of CBD on different types of anxiety, the effects of prolonged use, and the most effective form of CBD and many more aspects of use. While there are claims that gain traction in the public eye that aren’t always backed by science, you may take some comfort in the fact that CBD has been shown to have some effects that reduce anxiety.
References:
Blessing, E. M., Steenkamp, M. M., Manzanares, J., & Marmar, C. R. (2015). Cannabidiol as a Potential Treatment for Anxiety Disorders. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, 12(4), 825–836. doi:10.1007/s13311-015-0387-1
De Gregorio, D., McLaughlin, R. J., Posa, L., Ochoa-Sanchez, R., Enns, J., Lopez-Canul, M. Aboud, M., Maione S., Comai S., and Gobbi, G. (2019). Cannabidiol modulates serotonergic transmission and reverses both allodynia and anxiety-like behavior in a model of neuropathic pain. Pain, 160(1), 136–150. doi:10.1097/j.pain.0000000000001386
Linares, I. M., Zuardi, A. W., Pereira, L. C., Queiroz, R. H., Mechoulam, R., Guimarães, F. S., & Crippa, J. A. (2019). Cannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking test. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999), 41(1), 9–14. doi:10.1590/1516-4446-2017-0015