Marijuana & Pain Relief: All In Your Head?

Confused or disappointed woman with hands up
The history of medicinal marijuana, particularly its pain-relieving properties, is explored in the context of the placebo effect in a Swedish study. The study, which analyzed 20 individual research reports involving over 1,400 participants, concluded that patients given placebos reported nearly two-thirds as much pain relief as those given genuine cannabinoids. The researchers also suggested that positive media reporting on medical marijuana may contribute to anticipated positive outcomes, enhancing the placebo effect. However, despite the placebo effect, other studies and patient reports indicate that medical marijuana provides substantial pain relief, often scoring higher than placebos.
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The history of medicinal marijuana goes back at least 5,000 years, and numerous healing traditions prize this herb for it its pain-relieving properties. Today millions of people around the world continue to embrace cannabis therapies for pain relief. But opponents ask: Are they just fooling themselves?

Marijuana & the Placebo Effect

A Swedish study released in November of 2022 suggested that much of the pain relief associated with marijuana therapy comes from belief, not pharmacology – a.k.a. the placebo effect, a phenomenon that’s well-known in medical science.

A British doctor first demonstrated the placebo principle more than 200 years ago by showing that four out of five patients reported relief from rheumatic pain after being hooked up to a phony cure-all device. Ever since, researchers have been working overtime to see if a given medication actually produces a positive effect, or if patients just experience a sense of improvement because they believe in the process. And while some might say, ‘Who cares as long as I feel better?’, that answer isn’t good enough for scientific minds.

It certainly wasn’t good enough for the authors of the Swedish study, who combed through 20 individual research reports involving more than 1,400 participants who were given cannabis-based treatments for pain relief. Therapies mentioned in these studies included THC and/or CBD combinations and various synthetic cannabinoids, administered in pill form, spray, oil, smoke, and vapor. The one thing all of these experiments had in common was that some participants were provided actual cannabinoids while others were given non-active placebos.

After tallying all the reported data, the authors concluded that patients given placebos reported nearly two-thirds as much pain relief as those given genuine cannabinoids. They also suggested that the media’s positive reporting on medical marijuana caused people to anticipate positive outcomes, which further contributed to the phenomenon of placebo pain relief.

So what’s the takeaway? Is simply believing in medical marijuana the reason people feel better, or is there more to the story?

The Power Of The Placebo Effect

Separating pharmacology from psychology is a problem that’s not unique to medical marijuana studies. The British Journal of Anesthesia states that “the placebo effect is often high in pain studies,” and notes that a patient’s expectation of pain relief can have a significant impact on outcome.

A study released in the January 2022 issue of The American Journal of Psychology reported that up to 60% of patients suffering from depression showed marked improvement after being treated with a placebo rather than an antidepressant medication. The authors also suggested that between 50 and 75% of the benefits provided by antidepressant medications were actually the result of the placebo effect. This anticipation of improvement makes it especially difficult to determine the effectiveness of a given medication.

To see if really it was “all in their head,” the researchers used advanced imaging techniques to measure brain activity in patients given either a placebo or one of two popular antidepressant medications. Nearly half of patients given antidepressant medication showed an improvement in symptoms, and nearly 40% of those given placebos showed improvement.

An analysis of brain activity revealed that the patients who showed no improvement from either placebo or medication exhibited no change in brain activity. Patients who responded favorably to medications showed changes in activity in certain areas of the prefrontal cortex, which is a region of the brain that influences personality. Less expected was the finding that the patients provided a placebo also showed a change in activity in the prefrontal cortex – though the changes were not identical to those created by medications.

This first-of-its-kind research raises some interesting avenues for further research into the link between expectation and brain chemistry. It also hints at a mechanism that may explain why placebo expectations may mirror the pain and stress-relieving effects of marijuana.

When cell tissues are damaged, they produce endocannabinoids that activate CB receptors to regulate pain responses. These are the same receptors targeted by THC and CBD. And though not conclusive, there are indications that placebo-generated responses to pain management may actually target the same CB receptors as marijuana. This may help to explain why both placebo expectation and medical marijuana can provide pain relief — though not necessarily to the same extent.

Placebos May Help, But Marijuana Scores Higher

Setting the placebo question aside for a moment, there’s plenty of evidence that medical marijuana helps with pain. We’ve shown that medical marijuana can provide effective pain relief, reported that low-dose THC can help manage pain, and shown how cannabis products can provide an effective alternative to pain pills.

But don’t just take our word for it. A broad study published in the journal Pain surveyed some 1,000 medical marijuana patients suffering from chronic pain. Each was asked to rate the effectiveness of medical cannabis in treating their symptoms or conditions based on a scale of 0 to 100, with 100 being complete relief. On average, these patients gave their medical marijuana therapies a score of 75% for pain relief. That number exceeds the placebo effect in the Swedish study mentioned above.

Another study reporting favorably on medical marijuana versus placebo for pain relief comes from a review of 34 individual clinical trials investigating the effect of cannabis and cannabis-based medicine on neuropathic, non-neuropathic pain, acute pain, and experimentally induced pain. Each of these studies included the administration of a placebo element to some participants instead of cannabis therapy.

Summing up the results, the authors state:

All studies but one showed a positive effect of cannabis on pain management compared to placebo.

In plain language, that’s a win for medical marijuana. While there is undeniably some degree of pain relief that you might get from simply believing that marijuana helps, surveys like this one show that a lot of real-world users get more relief from the real thing.

A final thought on the subject comes from a blog published on Harvard Health, which quotes Ted Kaptchuk, the Director of the Program in Placebo Studies at Beth Israel Deaconess Medical Center. In a nutshell, his message was to focus less on the reasons why, and more on the results themselves.

His advice?

If something helps relieve your pain and doesn’t cause any significant harm, I would say go ahead and use it.

CannaMD agrees with this insight, with the added caveat that you should always seek the advice of a qualified medical professional before beginning any type of cannabis therapy.

Updated: March 5, 2024

Pierce Hoover

Pierce Hoover is a career journalist with more than three decades of experience in print, broadcast and online writing, editing and reporting, with more than 5,000 articles published in national and international print media and online. His focus on medical marijuana therapies mirrors his broader interest in science-based alternative medical practices.


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