The Endocannabinoid System
To understand how cannabis might help with chronic back or neck pain, you first need to understand how cannabis interacts with the human body.
Cannabis affects humans when its active chemicals, called cannabinoids, are processed by the body’s endocannabinoid system. This crucial system present throughout the human body controls or effects some of its most important functions, such as hunger, stress response, memory building, inflammation, sleep, muscle control, energy, pain and mood regulation.
The endocannabinoid system is made up of three main parts: endocannabinoids, receptors and enzymes. The endocannabinoids are molecules very similar to the cannabinoids found in cannabis, but they are produced by the human body naturally. These endocannabinoids bond with endocannabinoid receptors (specifically called CB1 and CB2 receptors), which are found throughout the body on the surface of cells. Then special enzymes break down endocannabinoids, clearing them from our system.
When working properly, this system is thought to help maintain homeostasis (or balance) in the human body.
One of the key functions of the endocannabinoid system is regulating pain sensation throughout all the stages of pain processing. While humans have been using cannabis as a pain killer for thousands of years, it was the relatively recent discovery of the endocannabinoid system, and study of its key functions, that has finally given us the ability to understand why.
The endocannabinoid system accomplishes its analgesic effects primarily through stimulating CB1 and CB2 receptors with the body’s natural endocannabinoids.
CB1 receptors are found throughout the peripheral and central nervous systems and can play a big role in pain signaling. Activating CB1 negatively regulates neurotransmission throughout the nervous system, reducing pain signals and our perception of pain. Stimulating CB1 receptors can even modify the emotional pain component, thereby modifying our emotional response to pain.
In one study demonstrating how CB1 affects pain, scientists genetically deleted CB1 from the peripheral nervous system (while still preserving it in the central nervous system) of mice, and then treated them with cannabinoids. In those mice without CB1, the analgesic effects of cannabinoids were greatly reduced, suggesting that peripheral CB1 stimulation is an important way that our endocannabinoid system can reduce pain.
CB2 receptors, on the other hand, are found primarily on immune cells, but these can also play a role in the resolution of pain states by regulating the activity of the central nervous system’s immune cells. For example, in one study, scientists chemically stimulated CB2 in mice and saw decreased behavior indicating a pain response. In studies looking at CB2, activating this receptor was able to reduce markers of both inflammatory pain and nociceptive pain (pain related to damage to the body).
While these effects were originally thought to come entirely from CB2’s presence on immune cells, new evidence has emerged suggesting CB2 receptors may also express on sensory neurons and nerve fibers. Scientists now believe that additional pathways exist through which CB2 may mediate pain signaling, such as an indirect activation of opiate receptors.
While scientists are still figuring out some of the finer details on how this all works, the research we have so far is clear that stimulating the endocannabinoid system can lead to reductions in pain. So theoretically, by activating into the endocannabinoid system’s receptors, cannabis should be able to produce pain relieving properties for the back, neck, and beyond.
Cannabis and Neck / Back Pain
When it comes to using cannabis specifically for back or neck pain, research is fairly limited. Most studies on cannabis and pain focus on neuropathic pain, or pain from conditions like cancer or HIV. Still, we can learn a lot about how cannabis might help back or neck pain from looking at the studies on how cannabis affects pain in general.
As we delve into the studies on cannabis and chronic pain, one thing is clear: pain is one of the most common reasons that patients report using medical cannabis. Surveys of why cannabis patients use cannabis medicinally have found that high percentages of patients use cannabis for chronic pain, with one study reporting numbers as high as 97%.
Even more interesting, these patients seem happy with the results. In one survey conducted by UC Berkeley, 81% of patients reported that cannabis alone was more effective at relieving their pain than using opioids, with similar results reported for patients using non-opioid painkillers.
Of course, survey data is notoriously unreliable because patients might not be able to tell whether they are being affected by cannabis, the placebo effect, or something else, when they are noticing pain relief. So, it’s important to also look at pre-clinical and clinical data where scientists can perform more controlled studies.
Researchers studying cannabis and pain have been mixed on their analysis of this research. There have been several large meta-reviews of the pain relieving properties of cannabis, and authors seem to disagree on just how convincing the evidence is. Still, pretty much everyone agrees that more research is needed to fully understand both how to best use the cannabis products that are commercially available, and whether the pain relief benefits outweigh any potential risks from cannabis.
For example, in a 2017 meta-review on the cannabis literature, the National Academies of Science and Engineering reported that there is substantial evidence that cannabis is an effective treatment for chronic pain in adults, and tends to produce a moderate level of relief. However, they specified that “very little is known about the efficacy, dose, routes of administration, or side effects of commonly used and commercially available cannabis products,” and the authors recommended more research be done to clarify these questions.
The authors of a 2019 review agreed both that there was some research pointing to cannabis’ efficacy for pain, and that the current research doesn’t adequately represent the cannabis products currently being used, and recommended caution.
They pointed out that it is still difficult to do clinically relevant studies on cannabis for pain because of research restrictions. The majority of the studies on cannabis’ pain relieving effects are using inhaled cannabis—rather than the tinctures and edibles being used by many chronic pain patients. And even these inhaled options are often supplied by governmental agencies and might not have chemical profiles similar to what is available in dispensaries. So there’s a big gap in research when it comes to scientists’ knowledge about the best ways to utilize the available cannabis products safely and effectively for pain relief.
A 2017 review of the evidence from Harvard University found “modest” evidence from clinical trials supporting the use of cannabis for pain. The survey also found initial evidence that cannabis could help with reducing opioid use when the two are used together. Still, like the other reviews, they recommended more research to better understand the potential side effects and gain more clarity around how to use cannabis for pain effectively.
Aside from these reviews, other studies have given us more insight into the ways different types of cannabis, or ways of using it, might affect pain. For example, one study found that using THC and CBD together improved pain relieving abilities of cannabis when compared to either one alone. Another study found that there were fewer negative gastrointestinal events when treating pain with cannabis when patients used inhaled methods, rather than taking cannabis orally.
Potential side effects of cannabis use
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