An introduction to arthritis

Arthritis is one of the most common conditions that people of all kinds experience around the world. In the UK alone, over 10 million people struggle with arthritis or related joint conditions. There are more than 100 different types of arthritis, and it doesn’t only affect the elderly. Many types, such as juvenile-onset arthritis and ankylosing spondylitis, can develop in adolescence.

The primary types of arthritis are rheumatoid arthritis, which is an autoimmune disease causing inflammation, and osteoarthritis, which is a degenerative condition that weakens cartilage and bones. The other primary categories of arthritis include fibromyalgia, an abnormal pain condition, and gout, which involves a build-up of uric acid crystals.

Arthritis is synonymous with joint pain, which can develop gradually or come on suddenly, and can affect one or multiple joints. Though it’s common in older people and there’s likely a genetic factor, arthritis can occur at any age, for people of any gender or ethnicity. In some cases, performing repetitive manual labour in certain lines of work can increase the risk of developing arthritis.

What happens when you have arthritis?

Across the different types of arthritis, many of the symptoms are similar. The main symptoms of arthritis are stiffness and swelling in and around the joints, causing pain and discomfort and limiting the range of motion. This can often result in fatigue and a loss of independent function, as arthritis can severely impact the ability to perform daily activities.

Arthritis can occur in any joint, but it most commonly affects the hands, including the wrists and fingers, and the knees, hips, and spine. It can often develop in ankles and toes as well. Some types of arthritis can damage other tissues throughout the body, including the eyes and lungs. The pain, restricted movement, and resulting muscle weakness can also lead to further health issues such as weight loss, sleeping problems, and depression or anxiety.

Unfortunately, there is no cure for arthritis, but there are treatments to help slow down the rate of tissue damage and allow patients to manage their pain levels. With such a high prevalence of arthritis in the population, it’s unsurprising that there is a growing interest in the use of medical cannabis to treat this progressive and painful condition. Let’s explore the evidence supporting the use of cannabis for arthritis.

Medical cannabis and arthritis: what does the evidence say?

Cannabis has many chemical constituents, and two such cannabinoids are a source of interest for research into alternative pain relief therapies. The most common is CBD (cannabidiol), which does not cause a high, while THC (tetrahydrocannabinol) is psychoactive.

It’s believed that the anti-inflammatory properties of these cannabinoids decrease swelling and block pain messengers in the body, which is helpful for relieving such symptoms of arthritis. Relieving pain and slowing disease progression can then contribute to better sleep and a better quality of life overall for those restricted by arthritic pain.

Understandably, people want to know that the science behind such statements is accurate before signing up for CBD treatments themselves. Here are several examples of published research into the effects of CBD and THC on arthritis symptoms over the previous 15 years:

  • 2006 – A human trial found that Sativex oral spray (containing CBD and THC) provided a ‘significant analgesic effect’ for rheumatoid arthritis patients and suppressed disease activity.1
  • 2011 – A study on male Wistar rats with arthritis found that CBD affects the way that atypical pain receptors respond to stimuli, suggesting further research into targeting these novel receptors to reduce inflammation and pain.2
  • 2014 – A review of the existing research on the effects of CBD on arthritic animals concluded that CBD could be an effective treatment for osteoarthritis, and that the endocannabinoid system is ‘an emerging therapeutic target for osteoarthritis pain’.3
  • 2016 – Another study on arthritic rats found that applying CBD gel significantly reduced swelling and pain, without psychoactive side effects.4
  • 2017 – A review found that selected cannabinoids led to a ‘significant, but clinically small’ pain reduction in patients with chronic neuropathic pain, with larger and more specific trials required to learn more about dosages, durations, and long-term physical and psychological effects.5
  • 2017 – Another study on rats also found that local administration of CBD blocked osteoarthritis pain and prevented inflammation.6
  • 2018 – A randomised pre-clinical trial in Australia found that male osteoarthritis patients using 250mg of topical CBD reported a greater pain reduction than those using a placebo, though there was little variability for female patients.7
  • 2019 – A review found that cannabinoids could be a suitable treatment for rheumatoid arthritis, but more clinical studies must focus on targeting specific pain receptors.8
  • 2019 – A Danish study found that patients with rheumatoid arthritis and ankylosing spondylitis reported a reduction in pain after 12 weeks of using CBD, and an improvement in quality of life after 24-36 weeks, with THC add-ons for those who didn’t respond to CBD treatment after 12 weeks.9
  • 2020 – A New Zealand review concluded that the endocannabinoid system does play a role in pain and inflammation, but while products such as Sativex have some efficacy for arthritis, more studies are still needed on the endocannabinoid system and the long-term effects of medicinal cannabis.10

As you can see, the studies on rats gave positive indications for the use of cannabinoids in treating arthritis, as did the majority of the studies on humans. That said, the research into the long-term effects and precise dosages for human beings is still in the early stages. Though official research is lacking, many people have already been using cannabinoids to treat painful conditions for years.

According to the Arthritis Foundation in America, at least 79% of their survey respondents have used or intend to use CBD, while 29% currently use CBD specifically to manage their arthritis symptoms. Patients using CBD reported experiencing not just pain relief, but also improved sleep and physical function, with reduced symptoms of anxiety and depression.

There’s no shortage of anecdotal evidence from arthritis patients who benefit from cannabis-based treatments. This is partially the reason that it’s already legal for registered medical specialists to prescribe cannabis-based medicinal products in the UK, but only for patients with cancer or chronic neuropathic pain when first-line treatments have failed.

Arthritis and the endocannabinoid system

So, how exactly do cannabinoids help with joint pain conditions such as arthritis? As mentioned earlier, the two most-researched compounds of the cannabis sativa plant are CBD and THC. However, the human body actually produces its own cannabis-like products – ‘endocannabinoids’ such as AEA (anandamide) and 2-AG (2-arachidonyl) – which researchers are also investigating.

The endocannabinoid system in the human body has 2 receptors, known as CB1 and CB2. It’s believed that cannabinoid-sensitive receptors like these are present in multiple tissues, including joints, bones, skin, and nerves – as seen in arthritic patients undergoing knee surgery. When CBD and THC encounter these receptors, they act like fat-based neurotransmitters, activating the receptors and blocking the progression of pain and inflammation.11

A Chinese study found unusually high levels of CB2 receptors in the joints of patients with rheumatoid arthritis, suggesting that targeting these specific receptors could help to treat the condition.12 As several of the studies listed above found, the fact that cannabinoid-based treatments target symptoms of arthritis via these receptors, specifically inflammation and pain, makes CBD and THC especially promising treatments for arthritic conditions.

CB1 receptors are mostly found in the central nervous system, while CB2 receptors are primarily found in the immune system.13 CBD most strongly impacts CB2 receptors, encouraging the body to produce more of its own cannabinoids, which in turn affects the body’s pain and inflammation responses. THC interacts most strongly with CB1 receptors, affecting cognitive co-ordination activities such as thinking, mood, and appetite.14

All the evidence points to the idea that, if the correct strain and dosage can be found, cannabinoid-based medicine can directly target the relevant receptors and effectively block inflammation and pain signals. In turn, reduced pain and swelling can improve related symptoms such as fatigue and poor mental health.

How does cannabis compare to current treatments for arthritis?

There are several categories of treatments for arthritis, and each individual patient is likely to require a tailored approach according to their specific circumstances. Current possible arthritis treatments include, but are not limited to:

  • Therapies such as physiotherapy, hydrotherapy, massage, acupuncture
  • Lifestyle changes like exercise, yoga, and conscious joint care (adjusting lifting, pushing, or pulling behaviours to reduce strain on the joints)
  • Medications including painkillers, non-steroid anti-inflammatory drugs, or disease-modifying anti-rheumatic drugs
  • Surgeries such as hip or knee joint replacements

In cases of severe chronic pain, patients can develop a tolerance to medications until they no longer work, or become addicted to prescription medications such as opiates.15 As cannabis is less addictive and rarely causes negative side effects, it’s an ideal option when first-line treatments don’t have the desired effects upon painful conditions like arthritis.

Another benefit is that there are many versions of cannabinoid products with various application methods, such as CBD oil for arthritis, which can be ingested orally or used as a topical ointment. This makes it easier to tailor its use to individual needs.

Despite the symptom-relieving and disease-slowing potential, it can still be difficult for patients to purchase cannabis oil for arthritis, or any other form of medicinal cannabis in the UK. Current regulations allow clinicians on the General Medical Council’s Specialist Register to prescribe medicinal cannabis for arthritis due to the chronic pain it causes.

At Cannabis Access Clinics, our specialist doctors and consultants can assess your suitability and decide whether cannabis could be helpful in treating your arthritis. Find out more about what the process looks like on our website, or book an eligibility consultation online to start your journey with medicinal cannabis for arthritis today.

References:

1) Blake DR, Robson P, Ho M, Jubb RW, McCabe CS. (2006). ‘Preliminary assessment of the efficacy, tolerability and safety of a cannabis-based medicine (Sativex) in the treatment of pain caused by rheumatoid arthritis’. Rheumatology, 45(1), pp. 50-52.

2) Schuelert N, McDougall JJ. (2011). ‘The abnormal cannabidiol analogue O-1602 reduces nociception in a rat model of acute arthritis via the putative cannabinoid receptor GPR55’. Neuroscience Letters, 500(1), pp. 72-76.

3) La Porta C, Bura SA, Negrete R, Maldonado R. (2014). ‘Involvement of the endocannabinoid system in osteoarthritis pain’. European Journal of Neuroscience, 39(3), pp. 485-500.

4) Hammell DC, Zhang LP, Ma F, Abshire SM, McIlwrath SL, Stinchcomb AL, Westlund KN. (2016). ‘Transdermal cannabidiol reduces inflammation and pain-related behaviours in a rat model of arthritis’. European Journal of Pain, 20(6), pp. 936-948.

5) Meng H, Johnston B, Englesakis M, Moulin DE, Bhatia A. (2017). ‘Selective Cannabinoids for Chronic Neuropathic Pain: A Systematic Review and Meta-analysis’. Anesthesia & Analgesia, 125(5), pp. 1638-1652.

6) Philpott HT, O’Brien M, McDougall JJ. (2017). ‘Attenuation of early phase inflammation by cannabidiol prevents pain and nerve damage in rat osteoarthritis’. Pain, 158(12), pp. 2442-2451.

7) Hunter D, Oldfield G, Sebree T. (2018). ‘Synthetic transdermal cannabidiol for the treatment of knee pain due to osteoarthritis’. Osteoarthritis and Cartilage, 26, S26.

8) Lowin T, Schneider M & Pongratz G. (2019). ‘Joints for joints: cannabinoids in the treatment of rheumatoid arthritis’. Current Opinion in Rheumatology, 31 (3), pp. 271-278.

9) Hendricks O, Andersen TE, Christiansen AA, Primdahl J, Hauge EM, Ellingsen T, Horsted TI, Bachmann AG, Loft AG, Bojesen AB, Østergaard M, Lund Hetland M, Krogh NS, Roessler KK & Petersen KH. (2019). ‘Efficacy and safety of cannabidiol followed by an open label add-on of tetrahydrocannabinol for the treatment of chronic pain in patients with rheumatoid arthritis or ankylosing spondylitis: protocol for a multicentre, randomised, placebo-controlled study’. BMJ Open, 9(6), e028197.

10) Berg MVD, John M, Black M, Semprini A, Oldfield K, Glass M, Braithwaite I. (2020). ‘Cannabis-based medicinal products in arthritis, a painful conundrum’. New Zealand Medical Journal. 133(1515), pp. 35-45.

11) Miller RJ, Miller RE. (2017) ‘Is cannabis an effective treatment for joint pain?’. Clinical and Experimental Rheumatology, 107(5), pp. 59-67.

12) Gui H, Liu X, Wang ZW, He DY, Su DF, Dai SM. (2014). ‘Expression of cannabinoid receptor 2 and its inhibitory effects on synovial fibroblasts in rheumatoid arthritis’. Rheumatology, 53(5), pp. 802-809.

13) Rahn EJ, Hohmann AG. (2009). ‘Cannabinoids as pharmacotherapies for neuropathic pain: from the bench to the bedside’. Neurotherapeutics, 6(4), pp. 713–737.

14) Pertwee RG. (2008) ‘The diverse CB1 and CB2 receptor pharmacology of three plant cannabinoids: delta9-tetrahydrocannabinol, cannabidiol and delta9-tetrahydrocannabivarin’. British Journal of Pharmacology, 153(2), pp. 199-215.

15) Labianca R, Sarzi-Puttini P, Zuccaro SM, Cherubino P, Vellucci R, Fornasari D. (2012). ‘Adverse effects associated with non-opioid and opioid treatment in patients with chronic pain’. Clinical Drug Investigation, 32(1), pp. 53-63.

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