CBD, Placebo Effect & Pain

Photo: Shutterstock
  • While proponents say that cannabidiol (CBD) offers many benefits, its most common use is pain management.
  • Scientists have not yet clinically proven the pain-relieving properties of CBD.
  • A new study shows that while CBD can help people deal with pain, this is due, at least in part, to a placebo effect.

People frequently promote CBD as a pain reliever despite the lack of clinical evidence to back up this claim. Researchers at Syracuse University (SU) in New York have recently carried out a study investigating CBD’s value as a pain reliever. They found that CBD may facilitate pain management due to a combination of its actual pharmacological properties and people’s expectations of pain relief.

The power of the placebo
SU psychology researcher Martin De Vita, the lead author of the study, explains the reason for the study:

“For science and the public at large, the question remained: Is the pain relief that CBD users claim to experience due to pharmacological effects or placebo effects? That’s a fair question because we know that simply telling someone that a substance has the ability to relieve their pain can actually cause robust changes in their pain sensitivity. These are called ‘expectancy effects.’”

The study is a follow-up to earlier research by De Vita, doctoral candidate Dezarie Moskal, and SU Professor Emeritus Psychology Stephen Maisto.

The team’s earlier work found that CBD and its corresponding expectancy effects did not so much reduce experimental pain intensity as make it more bearable. As De Vita explains, they were “changing the channel, making it a little less unpleasant.”

De Vita says of the current study:

“We hypothesized that we would primarily detect expectancy-induced placebo analgesia (pain relief). What we found, though, after measuring several different pain outcomes, is that it’s actually a little bit of both. That is, we found improvements in pain measures caused by the pharmacological effects of CBD and the psychological effects of just expecting that they had gotten CBD. It was pretty remarkable and surprising.”

The findings appear in the journal Experimental and Clinical Psychopharmacology.

Separating CBD from placebo
The study involved 15 healthy adults from the Syracuse community who were not currently taking any pain medications and were aged 18–30 years.

The researchers excluded older adults, as previous research has indicated that older people are more likely to have developed altered pain reactivity or sensitivity, which could skew experimental results.

After using heat to induce pain safely in the study participants, the researchers measured their nervous system responses. Describing the experiment, De Vita says, “Then we administer a drug, like pure CBD, or a placebo and then reassess their pain responses and see how they change based on which substance was administered.”

The experiment used CBD oil, but De Vita cautions that other forms of CBD might produce different results.

The researchers also wanted to assess expectancy effects, so they told some people who had received CBD that they had received a placebo. They also told some people that they were getting CBD rather than the placebo.

“That way,” De Vita explains, “we could parse out whether it was the drug that relieved the pain, or whether it was the expectation that they had received the drug that reduced their pain.”

De Vita notes that pain is not a simple phenomenon. It involves the physical, or “sensory,” perception of pain’s intensity, as well as the person’s emotional, or “affective,” response to pain.

The team explored both sensory and affective responses to pain in an attempt “to pop the hood and start looking at some of these other mechanistic pain processes,” as De Vita puts it.

The researchers measured the effects of CBD, expectancy, or both on six different aspects of pain:

  • pain threshold
  • pain tolerance
  • pain intensity
  • pain unpleasantness
  • conditioned pain modulation, which is the degree to which the body can alter a pain signal in the brain to make it more tolerable
    offset analgesia, which is the difference between a reduction of pain and an individual’s perception of that reduction

CBD versus the placebo effect
The experiments resulted in complex, often contradictory findings.

For example, the pharmacological effect of CBD had the greatest effect on one aspect of pain, whereas, for another, it was the participants’ expectancy.

For some aspects of pain, CBD and expectancy produced a similar effect. In other cases, the most pronounced benefit came from a combination of the two.

“We were going into this,” says De Vita, “thinking we were going to primarily detect the expectancy-induced pain relief, but what we found out was way more complex than that, and that’s exciting.”

De Vita told Medical News Today:

“It’s always a good idea to explore the pharmacological and psychological effects of substances. This is especially the case with pain research because the pain experience can be dramatically influenced by psychological factors. If we can increase our understanding of how substances affect us, we can help providers, patients, and consumers make informed decisions.”

De Vita added that since “this is the first human experimental pain study on CBD, research still needs to examine its effects in different clinical pain populations. We’ve got a lot of catching up to do!”