CBD oil and pain: physiology, placebo, or both?
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Chronic pain seems to be a serious affliction for large number of people, and in particular, an increasing number of young people. A new report has found that the proportion of people in England aged 16 to 34 affected by high-impact chronic pain has risen dramatically between 2011 and 2017. They define this as pain so acute that it lasts over 12 weeks despite treatment or medication.
Long-term reliance on opioid drugs is recognised as an undesirable way of treating chronic stress in the longer term. In fact, promoting physical activity and tackling obesity might tackle some factors that may be responsible for this more widespread experience of chronic pain.
CBD oil and pain: Placebo effect?
But is there another treatment that might help while we encourage people to make these behavioural changes? What is the evidence that cannabidiol (CBD) oil may help with chronic pain? And if this works, how much of this is because of physiological mechanisms attributable to CBD oil versus a placebo effect? A recently published study investigated exactly this.
As stigma around cannabis use slowly erodes and legislation around cannabis use liberalises, people have largely reported cannabis to provide similar pain relief compared to other medication. This finding extends to forms of cannabinoids such as CBD oil which seems to have a medium-to-large effect on self-reported pain. Placebo treatments also seem to have a small-to-medium effect on self-reported pain. We know perception can heavily influence that pain. It has been difficult to disentangle how much of the pain-relieving effects of cannabinoids are due to intoxication, placebo effect and/or direct physiological action. A recent balanced placebo experimental pain study sought to understand the independent and/or combined effects of expecting to take or actually taking CBD oil on pain reactivity.
In the study, the researchers randomly assigned participants to four experimental conditions where they received instructions along with the investigational product: control (told and given inactive drug); expectancy (told active, given inactive); drug (told inactive, given active CBD oil); and expectancy plus drug (told and given active). After a 30-minute absorption period, two thermodes capable of applying 20 to 52 °C (quantifiable sensory stimuli) were applied and used to evaluate static and dynamic pain measures in different ways.
The results showed obvious effects in only two measurements. Unpleasantness, a static pain measure, was equally reduced by both CBD alone and expecting to get CBD: both the placebo effect and CBD seemed to reduce this aspect of pain, but the combination of CBD and expectancy did not provide any additional benefit. Continuous pain modulation, a dynamic pain metric, was also affected by expectancy and CBD alone. Curiously, their combination also seemed to have no additional effect.
Direct physiological and placebo effects can co-exist
So what can we make of these results? The short story is that psychological expectancies and pharmacological action drive CBD-induced reductions in pain. However, we need to exercise some caution here. Pain itself is a complex phenomenon that many variables can influence, some of which are not completely understood — this is even more so for chronic pain.
This study was limited to acute treatment, heat-induced pain, and participants were also advocates of CBD use. It’s not clear if this placebo effect of CBD would have an effect beyond acute treatment and/or in pain stimuli that is not heat-induced. There is evidence to suggest that CBD has antioxidant and anti-inflammatory properties that may be directly or indirectly related to chronic pain and associated conditions like rheumatoid arthritis, but further studies with long-term CBD exposure would be needed to paint a clearer picture.
Wider work makes one thing clear: Even when participants are told about the power of the placebo effect, they can still experience the placebo effect. And this may occur for hemp or CBD oil at the same time as direct physiological effects. However, they don’t seem to have an additive effect. Exactly why this is remains a mystery to be solved.