Evelynne Morris, Ireland Buckley, Gabbi Marchelli, Dena Quigley, Ph.D.
Abstract This experiment studied whether a cannabidiol (CBD) placebo, coconut oil, plays a role in relieving stress. Acting as a stress-inducing stimulus, the Stroop test is a video that requires participants to say the color of the word rather than the word itself when projected on the screen. While administering the Stroop test to a group of college participants ranging from 19 to 21 years of age, change in heart rate and mean arterial pressure were measured using a blood pressure cuff and pulse plethysmograph. Coconut oil, the CBD placebo, was administered to the participant’s temples and neck before repeating the Stroop test. Mean arterial pressure was found to be significantly lower when the participant believed they were using CBD. Heart rate also decreased when the placebo was used. At various intervals during the study, personal surveys asked for the participant’s current stress level on a standardized scale from 1-10 and their view on the given drug. Recorded results displayed a general decrease in indicated stress levels after the CBD placebo was administered. The findings from this study are expected to spike interest in continuing to study the uses and effects of CBD.
Introduction Recent studies focusing on cannabidiol (CBD), a Cannabis sativa constituent, have shown the drug’s powerful effect on treating neuropsychiatric disorders. Specifically, CBD has been shown to possess anti-inflammatory and anti-anxiety properties (Aubrey, 2018). As cannabidiol has increasingly become well-known as a “magic” drug, it is unknown to what extent a psychological factor, the placebo effect, influences the decrease of stress-induced heart rate and blood pressure. By measuring the effect of a placebo in place of CBD, we will learn how influential the placebo effect is at mitigating stress-related symptoms. Evidence has shown that patient expectations about medicines influence how the patient feels after taking medication (American Cancer Society, 2015). The placebo effect can be verbally induced or result from conditioning, as well as prior experiences (Munnangi, 2019). Optimistic expectations lead to a positive response, and negative expectations lead to inhibition of the desired response (Benedetti, 2013). For instance, if someone expects CBD to work, there should be a higher chance that the given CBD placebo will show a decrease in the stress factors of heart rate and blood pressure on a person. This is the main hypothesis being tested in our experiment. We hypothesize that, as a psychological factor, the perception alone of using CBD oil will decrease blood pressure and heart rate in response to a stressful stimulus. In our research, the stressful stimulus is a Stroop test video. In this test, participants had to say aloud the color of the word that they saw flash before them on the screen. As the video progressed, the flashing of words on
the screen increased in speed. The final round (Round 4) projected words on the screen at such a high pace that made it difficult to process the word before the next appeared (MindfulThinks, 2017). Although it does stem from the marijuana plant, the removal of tetrahydrocannabinol (THC) leaves CBD oil with none of the psychoactive components. The use of CBD interacts with several receptors that regulate fear and anxiety, such as the cannabinoid type 1 receptor (CB1R), the serotonin 5-HT1A receptor, and the transient receptor potential vanilloid type 1 (TRPV1) (Blessing, 2015). As part of the endocannabinoid system, CB1R functions as an inhibitory Gi/o protein-coupled receptor that is densely distributed in the basal ganglia. The CB1R involves the cAMP signal transduction pathway. In this pathway, when the ligand binds to the G-protein coupled receptor, the alpha subunit migrates to adenylyl cyclase creating cAMP from ATP. When the CB1R is activated, Gi activates, which decreases intracellular cAMP concentration by inhibiting the production of adenylyl cyclase, the main enzyme used in this pathway (Blessing, 2015). Described as an anxiolytic, CBD has in the past few years been used as a therapeutic drug to combat anxiety disorders and PTSD. By administering CBD, acute increases in heart rate and blood pressure were typically reduced (Blessing, 2015). Regarding the myocardial physiology, heart rate is determined by the conductive autorhythmic cells in the heart which demonstrate pacemaker activity (Costanzo, 2018). The action potentials travel down along cardiac muscle membrane
Scientia 2020 | 11
Original Research
Effect of Using CBD Placebo Under Stress: Measuring Heart Rate, Mean Arterial Pressure, and Reported Stress Level
