Cannabinoids for Fibromyalgia Pain: A Critical Review (2015–2019)

Fibromyalgia is one of the most common chronic pain conditions in the world, affecting around 11 million people in the United States alone – and about 6-7% of people across the globe in the latest studies. It's yet another health condition that modern medicine hasn't found a very good answer for – until the reintroduction of cannabinoid medicine. The research is exciting to see the promise for tomorrow.

Living with this condition obviously can be incredibly painful. Symptoms are widespread and include musculoskeletal pain, extreme levels of fatigue, problems with cognition, and very poor sleep quality. And, unfortunately, there is no cure although when analyzing the last 5 years of cannabinoid research including that of the famed Professor Mechoulam of Israel, things are changing.

Basic or standard medical treatment is limited to pain relief medication, anti-depressants, muscle relaxants, and sleep aids for many patients which quite simply isn't the best of options when nature could possibly be the answer. Sometimes physiotherapy or other lifestyle changes, such as low-impact exercise, are also recommended. But these treatments don’t work for everyone and sometimes the medication prescribed can come with a raft of unfortunate side effects.

Because of these limitations, many fibromyalgia patients have continued to experiment with different methods of managing their pain, such as cannabis. But is the popular plant really an effective treatment for fibromyalgia? If one were to just consider anecdotal evidence, it seems the answer would be a firm yes. So let's take a look at this round up of research and see why.

Cannabinoids for fibromyalgia pain: a critical review of recent studies (2015–2019)

• Erinn C. Cameron &
• Samantha L. Hemingway

Journal of Cannabis Research volume 2, Article number: 19 (2020) Cite this article

Abstract

Introduction

Fibromyalgia is a chronic health condition characterized by widespread, severe musculoskeletal pain that affects an estimated 5–7% of the global population. Due to the highly comorbid nature of fibromyalgia, patients with the disorder often respond poorly to traditional pain treatments. Recent studies suggest that patient response may be more favorable to alternative analgesics, such as cannabis. However, the therapeutic potential of cannabis-based pain treatment for fibromyalgia remains unclear. The present study examined the most recent cannabis literature (2015–2019) and provides a critical review of current research on the safety and efficacy of medical cannabis treatments for fibromyalgia.

Methods

We followed Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines in searching the PubMed and Medline databases using the search terms “cannabis + fibromyalgia” and then “cannabinoids + fibromyalgia.” Inclusion criteria were a) English language, b) published in peer review journals, c) published from 2015 to 2019, d) all study designs except for systematic reviews and meta-analyses, and e) all cannabis preparations.

Results

The search identified five applicable studies involving 827 participants that used six different treatments. Review suggested several methodological problems pertaining to generalizability and validity.

Conclusion

Although the critically reviewed studies superficially suggest that medical cannabis is a safe and effective treatment for fibromyalgia pain, serious methodological limitations prevent a definitive conclusion regarding the use of cannabinoids for pain management in fibromyalgia patients at this time.

Fibromyalgia is associated with widespread musculoskeletal pain that is commonly accompanied by additional symptoms such as fatigue, cognitive problems, mood disturbances, and problems with sleep (Clauw 2015; Palagini et al. 2016). In the absence of a definitive cure for fibromyalgia, treatment primarily focuses on symptom management and improving patient quality of life. Fibromyalgia is significantly more common in women and has a prevalence rate of 4% across Europe and North America with an approximated worldwide prevalence of 5–7% (Lan et al. 2016; Queiroz 2013). Additionally, some fibromyalgia patients experience psychological, social, and behavioral symptoms that further affect overall functioning and quality of life. While once considered a mysterious or unspecified condition of psychological or emotional origin, there is now empirical evidence, such as brain imaging studies, which have highlighted several biological underpinnings of many common fibromyalgia symptoms (Pomares et al. 2017; Schmidt-Wilcke and Diers 2017).

Pathophysiological symptoms of fibromyalgia include a sensitized or hyperactive central nervous system that is associated with an increased gain in pain and sensory processing (Clauw 2015; Queiroz 2013). Fibromyalgia can occur alone but is often comorbid with conditions such as irritable bowel syndrome (IBS) and tension headaches (Clauw 2015). It is also highly comorbid with a variety of autoimmune disorders characterized by inflammation, such as rheumatoid arthritis. When comorbidities are present, centralized pain can stem from various problems, making it hard to identify the precise source. Research has shown that fibromyalgia patients with comorbid disorders where the common pathway is pain are less likely to respond to typical pain treatments such as surgery or opioids (Clauw 2015).

Moreover, results have shown that, in some cases, fibromyalgia patients with multiple comorbid conditions that lead to pain respond well to centrally acting pharmacological therapies, such as cannabis (Fitzcharles et al. 2018; Phillips and Clauw 2013; Russo 2016; Walitt et al. 2016). However, there is conflicting evidence in the extant literature regarding the use of cannabis with fibromyalgia patients. Recent systematic reviews of randomized clinical trials (RCTs) examining the use of medical cannabis in the treatment of chronic pain presented limited and ambiguous evidence that cannabis exhibits analgesic properties for chronic pain resulting from fibromyalgia (Fitzcharles et al. 2018; Walitt et al. 2016). These results, in combination with rapidly changing national policies regarding cannabis use, highlight the need for an investigation of more recently published literature on this topic.

Minimal recent research has examined the use of cannabis for pain reduction in patients with fibromyalgia, with existing studies offering limited evidence for safety, efficacy, and tolerability. Moreover, there is a lack of methodological rigor among existing studies in this area. Additionally, comparative analysis of systematic data across relevant studies is challenging due to the low number of overall studies and the significant limitations, vast differences in methodology, and inconsistent results. Recent systematic reviews regarding the use of cannabis for fibromyalgia pain have been limited in scope, with only one identified study focusing solely on fibromyalgia patients (Walitt et al. 2016). Further, limitations include a lack of investigation of herbal preparations, with a majority of studies focusing on synthetic preparations. Also, few studies covered a broad range of study designs, focusing mainly on randomized clinical trials (RCTs). This review briefly summarizes the role of the endocannabinoid system in pain management with fibromyalgia patients and provides a critical review of selected studies from 2015 to 2019.

Endocannabinoid system and pain management

Research has indicated an extensive endocannabinoid system in animals, comprised of systemic endogenous ligands and receptors with critical localization to nervous tissue in both the central nervous system and the immune system (Donvito et al. 2017; Fitzcharles et al. 2016; Silver 2019; Walker et al. 2019). The primary function of the endocannabinoid system in humans is to maintain homeostasis, which includes regulation of pain and inflammation (Fitzcharles et al. 2016; Guindon and Hohmann 2009; Silver 2019). The endocannabinoid system is integral to normal physiological functioning in humans and has been associated with the pathology of several neurological conditions (Russo 2016). In addition to endogenous endocannabinoids, exogenous molecules with cannabinoid properties, such as botanical cannabinoids, engage the endocannabinoid system (Silver 2019). Traditionally utilized as a plant preparation derived from Cannabis sativa, cannabinoids have been widely used throughout history for medicinal effects (Bridgeman and Abazia 2017).

Studies have indicated that cannabinoids play a role in the following physiological processes in human: neuronal plasticity (Azad 2004; Viveros et al. 2007), pain (Guindon and Hohmann 2009; Khasabova et al. 2008), anxiety (Gray et al. 2015), inflammation (Guindon and Hohmann 2009; Nakajima et al. 2006), neuro-inflammation (Malek et al. 2015), immune function (Cabral et al. 2015), and metabolic regulation (Jesudason and Wittert 2008). Additionally, research has shown that 62% of licensed medical cannabis users in the United States report chronic pain as their top reason for use (Boehnke et al. 2019). Other results have indicated that neuropathic and musculoskeletal pain are the two commonest reasons why individuals who suffer from chronic pain choose medical cannabis as an alternative analgesic (Fitzcharles et al. 2016; Vučković et al. 2018). This review will focus on musculoskeletal pain as a form of chronic pain experienced in conjunction with fibromyalgia.

Cannabis use for symptom relief

An increasing number of women are reporting cannabis use for symptom relief, particularly for the relief of chronic pain associated with health problems that are more common in women, such as fibromyalgia (Finseth et al. 2015; McConnell et al. 2014; Ryan-Ibarra et al. 2015). While there are many cannabis treatments available, and recent research has indicated that cannabinoids of all types act simultaneously on multiple pain targets in the human body (Morales et al. 2017), existing evidence has been interpreted inconsistently. Currently, the efficacy, tolerability, and safety of cannabinoids for pain management with fibromyalgia patients is highly questionable. Additionally, available research in this area has many limitations, including the lack of clinical trials, problems with internal and external validity, low sample sizes, short treatment duration, lack of generalizability, contradicting results, and modest observable effects. Our review covers gaps in the literature by reviewing studies from the past 5 years only, thereby providing the most recent coverage. Further, we included a broader range of studies such as comparative studies, observation studies and retrospective reviews, whereas the majority of past reviews only included RCTs.

Method

The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) was used for this review (Moher et al. 2009). We identified Medline and PubMed as databases for our research. A search was conducted in October 2019 using the keywords “cannabis + fibromyalgia” and then “cannabinoids + fibromyalgia.” Specific inclusion criteria were as follows: a) English language, b) published in peer review journals, c) published from 2015 to 2019, d) RCTs, comparative studies, observational studies, or retrospective reviews, and e) all cannabis preparations. Systematic reviews, meta-analyses, and literature older than 2015 were not included in this review.

Results

The initial search returned a total of 47 articles. The removal of duplicates resulted in 28 articles. All authors reviewed abstracts to determine relevance to the review topic. After eliminating articles that were not in English and those that did not meet study criteria, only five articles were deemed relevant; four from Israel and one from the Netherlands (Habib and Artul 2018; Habib and Avisar 2018; Sagy et al. 2019; Van de Donk et al. 2019; Yassin et al. 2019). Studies that discussed the role of cannabinoids in conditions other than fibromyalgia were included only when the study also referenced fibromyalgia. The reference sections of the selected articles were also reviewed for additional studies, although no additional studies were included. The goal was to critically analyze only the most current studies regarding cannabinoids in the treatment of chronic pain in fibromyalgia patients. Figure 1 presents a flow chart outlining our literature search process. See Table 1 for a summary of selected studies.

Enjoy the balance of this research at: https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-020-00024-2

Thank you,

Mike Robinson,

Founder, Global Cannabinoid Research Center