Clinical Review

The Highs and Lows of Medical Marijuana

Clinician Reviews. 2016 October;26(10):40-42,44,53

References

1. Greydanus DE, Hawver EK, Greydanus MM, Merrick J. Cannabis: effective and safe analgesic? J Pain Manage. 2014;7(3):209-233.
2. Bostwick JM. Blurred boundaries: the therapeutics and politics of medical marijuana. Mayo Clin Proc. 2012;87(2):172-186.
3. Karst M, Wippermann S, Ahrens J. Role of cannabinoids in the treatment of pain and (painful) spasticity. Drugs. 2010;70(18):2409-2438.
4. Owen KP, Sutter ME, Albertson TE. Marijuana: respiratory tract effects. Clin Rev Allergy Immunol. 2014;46(1):65-81.
5. Hall W, Degenhardt L. Adverse health effects of non-medical cannabis use. Lancet. 2009;374(9698):1383-1391.
6. Volkow ND, Baler RD, Compton WM, Weiss SRB. Adverse health effects of marijuana use. N Engl J Med. 2014;370(23):2219-2227.
7. National Conference of State Legislatures. State medical marijuana laws (updated 7/20/2016). www.ncsl.org/research/health/state-medical-marijuana-laws.aspx. Accessed September 7, 2016.
8. Belendiuk KA, Baldini LL, Bonn-Miller MO. Narrative review of the safety and efficacy of marijuana for the treatment of commonly state-approved medical and psychiatric disorders. Addict Sci Clin Pract. 2015;10(1):1-10.
9. Hoffmann DE, Weber E. Medical marijuana and the law. N Engl J Med. 2010;362(16):1453-1457.
10. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: American Psychiatric Publishing; 2013.
11. Koppel B, Brust J, Fife T, et al. Systematic review: efficacy and safety of medical marijuana in selected neurologic disorders. Neurology. 2014; 82(17):1556-1563.
12. Smith LA, Azariah F, Lavender VT, Stoner NS, Bettiol S. Cannabinoids for nausea and vomiting in adults with cancer receiving chemotherapy. Cochrane Database Syst Rev. 2015;(11):CD009464.
13. Lutge EE, Gray A, Siegfried N. The medical use of cannabis for reducing morbidity and mortality in patients with HIV/AIDS. Cochrane Database Syst Rev. 2013;(4):CD005175.
14. Gloss D, Vickrey B. Cannabinoids for epilepsy. Cochrane Database Syst Rev. 2012;(6):CD009270.

Multiple sclerosis

For centuries, marijuana has been used for pain relief. The discovery of cannabinoid receptors in high concentrations throughout pain pathways of the brain supports the notion that marijuana plays a role in analgesia. While response to acute pain is poor, there is evidence to suggest that various cannabis formulations relieve chronic neuropathic pain and spasticity, as seen in multiple sclerosis.^3,6

Subjective improvements in pain and spasticity were seen with the use of oral cannabis extract, THC, and nabiximols.¹¹ Smoked marijuana is of uncertain efficacy and is not recommended for use in this patient population; it has been shown to potentially worsen cognition.^8,11

Seizures

Research into the role of marijuana in decreasing seizure frequency is inconclusive.¹¹ Large studies with human subjects are lacking, and most data thus far have come from animals and case studies.⁸ Some case reports have suggested a decrease in seizures with marijuana use, but further investigation is needed.⁶

At this time, it is not appropriate to recommend marijuana for patients with seizure disorders, but the use of cannabidiol might be more promising. Studies are ongoing.¹⁴

Alzheimer disease

Alzheimer disease is the most common cause of dementia.⁸ Despite known adverse effects on memory and cognition with acute use, studies have shown that marijuana might inhibit the development of amyloid beta plaques in Alzheimer disease.⁴ Further research on dronabinol has not provided sufficient data to support its use, and no studies utilizing smoked marijuana have been performed.⁸ Therefore, no recommendations exist for the use of marijuana in this patient population, and further research is warranted.

Ongoing research

There are some additional areas of potential therapeutic use of marijuana. Limited evidence has revealed that marijuana has anti-inflammatory properties, leading researchers to examine its use for autoimmune diseases, such as rheumatoid arthritis and Crohn disease. Studies investigating marijuana’s potential ability to inhibit cancer growth and metastasis are ongoing.

Unfortunately, research in patients with Parkinson disease has not shown improvement in dyskinesias.¹¹ Studies on other movement disorders, such as Tourette syndrome and Huntington disease, have not shown symptom improvement with marijuana use. Research on these conditions and others is ongoing.

CONCLUSION

Marijuana use has negative effects on a variety of body systems, but it also may provide therapeutic benefit in certain patient populations. Clinicians and patients are currently hampered by the dearth of reliable information on its safety and efficacy (resulting from federal restrictions and other factors). Comparative studies between marijuana and established standards of care are needed, as is additional research to identify therapeutic effects that could be maximized and ways to minimize or eliminate negative sequelae.