The use of cannabis or marijuana, for medicinal purposes is deeply rooted through history, dating back to ancient times. It once held a prominent position in the history of medicine. The father of modern medicine, Sir William Osler, published the textbook, ‘The Principles and Practice of Medicine’
In this he advocated for cannabis (cannabis indica) use in migraine;
Cannabis fluid extract medicine bottle from 1906
The use of marijuana based products to treat neurologic disorders dates back to the 1800s. Through the decades, this plant has taken a fascinating journey from a legal and frequently prescribed status, to illegal, driven by political and social factors rather than by science.
The plant genus Cannabis is a member of the plant family Cannabaceae, and there are 3 primary cannabis species which vary in their biochemical constituents: Cannabis sativa, Cannabis indica, and Cannabis ruderalis. Marijuana is derived from the plant Cannabis sativa, which contains over 60 different pharmacologically active compounds referred to as cannabinoids. Delta-9-tetrahydrocannabinol (THC) is the major psychoactive compound which causes the euphoric effect. Other cannabinoid compounds such as cannabinol and cannabidiol (CBD) are not known to have psychoactive properties. The psychoactive effects can acutely alter a patient’s cognition and inhibit normal functioning. Long term effects on learning and memory may occur. Thus, from a safety perspective, the use of products with a high THC component is controversial.
Cannabis works in the brain through the endocannabinoid system. This system is widely distributed throughout the brain and spinal cord. An endocannabinoid deficiency is theorized to underlie the pathophysiology of migraine or headaches. Cannabinoids are active through CB1 (cannabinoid 1) receptors in the areas of the brain and brainstem involved with migraine pathophysiology.
The American Academy of Neurology released a position statement in 2014, which was updated in 2018, recognising that cannabinoid compounds may have the potential for therapeutic benefit in some neurologic disorders. In terms of research however, most studies are small and poorly designed. They expressed concern with regards to the psychiatric and neurocognitive adverse effects that have been described. The interaction of these compounds with prescription medications, which are often required in patients with chronic, complex neurologic diseases, is also uncertain.
The AAN therefore does not advocate for the legalization of marijuana based products for use in neurologic disorders at this time, as it is felt that further research is needed to determine the safety and benefits of such products.
As we have seen therefore, there is anecdotal evidence and historical accounting of cannabis use for headache. Research however, in particular, controlled clinical trials evaluating formulations of medicinal cannabis or prescription cannabinoids for either acute or prophylactic therapy in migraine or other headache disorders is required before their use can be supported.
Position Statement: Use of Medical Marijuana for Neurologic Disorders, American Academy of Neurology, 2014
Comprehensive Review of Medicinal Marijuana, Cannabinoids, and Therapeutic Implications in Medicine and Headache, Baron, Headache Currents, 2015
Cannabis for Pain and Headaches: Primer, Kim, Fishman, Current Pain Headache Reports 2017 Apr; 21(4):19
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