Study under review: The Effects of Cannabidiol and Analgesic Expectancies on Experimental Pain Reactivity in Healthy Adults: A Balanced Placebo Design Trial
Before modern medicine, supernatural theories driven by social influence were used to explain and treat disease, leading to the use of techniques like bleeding or applying leeches to remove ‘bad blood’. While human understanding of disease has progressed tremendously, pain, despite our physiological understanding, can be heavily influenced by perception. For example, in a meta-analysis of 58 studies, the description of a placebo treatment as a painkiller resulted in a large pain-relieving effect on experimentally induced pain in healthy adults.
In the context of an opioid abuse epidemic, people are seeking alternative pain-relieving treatments and, as stigma surrounding cannabis slowly erodes with increasing legalization, cannabis has been overwhelmingly reported by people to provide similar pain relief when compared to other medication. Indeed, a recent meta-analysis of RCTs reported that cannabinoids, such as cannabidiol (CBD) and psychoactive delta-9-tetrahydrocannabinol (THC), can have a medium–large effect on self-reported pain. Interestingly, the placebo treatment had a small–medium effect on self-reported pain. Thus, it is unclear whether the pain-relieving effects attributed to cannabinoids are due to intoxication, the expectation of an effect (a placebo effect), and/or a direct pharmacological action on pain. One RCT reported that THC alone did not improve pain in patients with advanced cancer, while THC combined with CBD did, compared to a placebo. This suggests that the some benefits of cannabinoids may not depend on the psychoactive effects of THC. CBD is relatively safe and well tolerated, shows low abuse potential, is non-psychoactive, and is most commonly used to manage pain. However, CBD’s mechanism of action is not completely understood. Hence there’s a heated scientific debate on the proportion of the effects that can be attributed to expectations of an effect (placebo effect) or pharmacological action. The authors of this balanced placebo experimental pain study aimed to determine the independent and/or combined effects of expecting to take, or actually taking, CBD on pain reactivity.
Pain can be heavily influenced by perception. Cannabidiol (CBD) has demonstrated pain-relieving potential, but whether its effects are driven by expectations, pharmacological action, or a combination of both, is unclear. This study was designed to tease out the independent and/or combined effects of expecting to receive or actually receiving CBD on pain reactivity.
Other Articles in Issue #80 (June 2021)
Mini: Phytonutrient supplements for cardiovascular disease markers
A recent umbrella review summarized the effects of plant-based supplements for cardiovascular disease markers. Be careful with directly comparing the numbers they report though!
Deeper Dive: A Mendelian randomization study sheds light on the effects of polyunsaturated fatty acids on heart disease
This study explored whether genes that bump specific PUFA blood levels led to heart disease and found some evidence for the possible benefits of EPA.
Deeper Dive: Can regular exercise and a good diet attenuate age-associated cognitive decline?
This large four-year trial found surprisingly little benefit from diet and exercise on brain health of older people. Here, we explore some possible reasons for this finding.
Lower fat intake, lower testosterone levels?
This meta-analysis found that swapping out fat for carbs can lower men's testosterone levels a tad. But the relationship's neither set in stone nor straightforward.
Interview: Elisabeth Bik, PhD
Microbiologist and scientific integrity consultant Elisabeth Bik discusses her background, the chilling effect of legal threats on scientific discourse, and more.
Meat in Mediterranean diets: helpful or hurtful for the heart?
How does adding increasing amounts of lean red meat to a Mediterranean diet affect lipids and lipoproteins? This study aimed to find out.
Deeper Dive: Does red meat worsen glycemic control and inflammation?
This meta-analysis suggests that red meat doesn't impact glycemic control or inflammation in healthy adults, at least in the short term.