MS Medical cannabis treatments have proved highly effective at managing many of the symptoms of multiple sclerosis (MS). Here, we take a look at which symptoms in particular are positively affected by use of cannabis or cannabis-based therapies.
Inflammation of neural tissue is the primary characterisation of multiple sclerosis. MS is an autoimmune disease in which the body’s own immune cells attack the central nervous system, leading to inflammation of the myelin sheaths that enclose the neurons (nerves) in the brain and spinal column. This inflammation ultimately leads to the myelin sheaths becoming irreparably damaged, which in turn causes a range of neurological symptoms including loss of motor control, muscle weakness and spasms, unstable mood and fatigue.
Cannabis is well-known to reduce inflammation, and has been used as an anti-inflammatory for thousands of years by physicians and herbalists the world over. In recent years, the ability of cannabis to reduce MS-related inflammation has been thoroughly investigated, and has provided the basis for the world’s first market-approved pharmaceutical—Sativex, produced by the UK company GW Pharmaceutical.
A cross-section of a mouse neuron showing the myelin sheath that surrounds it (© JCB Images)
Research has demonstrated that agonists of the CB1-receptor (such as ??-THC or the endogenous agonist anandamide) exert a neuroprotective effect in individuals suffering from MS by reducing the immune response and therefore reducing inflammation. In one important study, mice bred to be deficient in CB1-receptors exhibited increased susceptibility to inflammation and neurodegeneration when infected with an animal model of MS known as experimental allergic encephalomyelitis.
Pain is one of the most common and debilitating symptoms of MS, and is experienced by 50-70% of sufferers. MS-related pain occurs either directly as a result of inflammation of neural tissue, or as a result of muscle spasms and spasticity exerting pressure on the musculoskeletal system.
Cannabis has proven ability to manage pain associated with MS. In a clinical trial conducted on humans in 2005, cannabis-based medicine delivered in the form of a sublingual spray was demonstrated to be significantly more effective than placebo at reducing pain and sleep disturbances in MS sufferers. Smoked cannabis has also been shown to be effective at reducing MS-related pain in several studies, including a patient survey of 112 MS sufferers from the US and UK in which the overwhelming majority reported a decrease in pain on smoking cannabis.
Inflammation of the neural tissues is the primary symptom of MS (© Ars Electronica)
Cannabis reduces pain in MS sufferers by directly working to reduce immune response and resultant inflammation, and also reduces musculoskeletal pain caused by muscle spasms and spasticity. A scientific review published in 2007 indicated that ??-THC was more effective at managing MS-related pain than CBD and dronabinol, a synthetic form of THC.
Muscle spasms—sudden, involuntary contractions of a muscle or muscle group—are another common feature of MS, and are reported by up to 80% of patients. Spasms can cause a sharp, temporary sensation of pain that usually disappears after a short time. Muscle spasticity is a related symptom, and refers to the state of constant contraction of a muscle or muscle group, leading to pain, stiffness and a sensation of “tightness”.
Cannabis has been demonstrated to both reduce the frequency of muscle spasms and the severity of muscle spasticity. In 2005, a randomised, double-blind, placebo-controlled, crossover study (considered the gold standard of clinical trials) found that 37 of 50 patients enrolled in the study showed improvements in mobility and the frequency of muscle spasms. A randomised controlled trial conducted in 2007 demonstrated that cannabis preparations were more effective than placebo at treating muscle spasticity, although this particular study did not reach statistical significance.
MS-related muscle spasms can be extremely painful and debilitating (© Dr Todd Cremeans)
The effect of cannabis on muscle spasms and spasticity is likely due to its ability to reduce inflammation of the neurons and slow the overall progression of the disease. A study published in Nature in 2000 demonstrated that cannabinoid receptor agonists including ??-THC and R(+)-WIN 55,212 (a synthetic agonist) ameliorated symptoms of spasticity and tremor, while antagonists of the cannabinoid receptors (particularly the CB1-receptor) exacerbated the symptoms.
Clinical depression is a common feature of multiple sclerosis, and is experienced by up to 50% of MS sufferers throughout the course of the illness. Depression in MS may occur due to damage to the nerves that help to regulate mood, or may be a side-effect of other medications used to control the progression of the disease. As well as major depression, MS can also lead to a range of associated symptoms of emotional dysfunction.
Major depression is experienced by around 50% of MS sufferers (© Violet Rose)
The ability of cannabis to treat depression is disputed, and there is substantial evidence on both sides. Several studies have indicated that ??-THC, CBD, and cannabichromene (CBC) can exert an antidepressant effect. The endocannabinoid system is known to play an important role in mood regulation and subjective levels of happiness, and endocannabinoids such as anandamide are fundamental to the process. It is believed that certain genetic variations in the expression of CB1-receptors render some individuals more susceptible to the mood-elevating effects of cannabis.
Over 90% of the 112 MS sufferers from the US and UK in the previously-cited survey reported that use of cannabis ameliorated symptoms of depression and emotional dysfunction. The relationship at work is complex, and subjective improvements in mood may be due to improvements in other symptoms that may cause emotional distress, including pain and spasticity, as well as by directly affecting neurons involving in mood regulation.
MS can lead to a range of gastrointestinal complaints including abdominal pain, constipation (experienced by around 50% of patients) and faecal incontinence (experienced by 30-50% of patients). These symptoms can be embarrassing, distressing and painful.
Gastrointestinal complaints are another common symptom of MS, and are experienced by up to 50% of patients (© Ashley Rose)
51-60% of the respondents of the patient survey reported that defecation urgency was reduced with use of cannabis, 44% reported that faecal incontinence was reduced, and 30% reported that constipation was eased. Cannabis has long been associated with gastrointestinal dysfunction including IBS and Crohn’s disease; it is believed that the effect of cannabinoids on the receptors (specifically the CB2-receptors) in the peripheral nervous system that controls gut function is responsible.