Unless you've been hiding under a rock, you've probably seen articles about a new study published in the journal Pharmacotherapy that discusses the impact of medical marijuana on migraine frequency.
Thanks to Congress and the Drug Enforcement Agency (DEA), there's a paucity of reliable information and virtually no studies about marijuana for any condition, including migraine. Under the Controlled Substances Act, cannabis is a Schedule I Controlled Substance. Schedule I substances cannot be used legally, even for clinical trials. The DEA defines a Schedule I substance as:
Substances in this schedule have no currently accepted medical use in the United States, a lack of accepted safety for use under medical supervision, and a high potential for abuse.
Some examples of substances listed in Schedule I are: heroin, lysergic acid diethylamide (LSD), marijuana (cannabis), peyote, methaqualone, and 3,4-methylenedioxymethamphetamine ("Ecstasy").2
The Pharmacotherapy Study:
"No clinical trials are currently available that demonstrate the effects of marijuana on patients with migraine headache; however, the potential effects of cannabinoids on serotonin in the central nervous system indicate that marijuana may be a therapeutic alternative. Thus, the objective of this study was to describe the effects of medical marijuana on the monthly frequency of migraine headache."1
- The study was a retrospective chart review.
- Charts from two medical marijuana clinics in Colorado were reviewed.
- The study included the charts of 121 adult patients with a primary diagnosis of migraine for whom medical marijuana was recommended for acute migraine treatment or migraine prevention.
- Patients were seen between January, 2010, and September, 2014, and each had at least one follow-up visit at the clinics.
- The primary outcome reviewed was the number of migraine attacks per month with medical marijuana use.
- Secondary outcomes evaluated were the type and dosage of the medical marijuana, previous and concurrent migraine treatments, and patient-reported effects.
- The number of migraine attacks per month was reduced from 10.4 to 4.6 with use of medical marijuana.
- Most of the patients studied used more than one form of marijuana.
- Most of the patients studied used marijuana daily for migraine prevention.
- Positive effects were reported in 39.7 percent of patients, most commonly:
- decreased migraine frequency reported by 19.9 percent and
- migraine attacks aborted reported by 11.6 percent.
- Negative effects were reported by 11.6 percent of the patients, most commonly:
- sleepiness in 1.7 percent,
- difficulty controlling the effects of marijuana in 1.7 percent.
"The frequency of migraine headache was decreased with medical marijuana use. Prospective studies should be conducted to explore a cause-and-effect relationship and the use of different strains, formulations, and doses of marijuana to better understand the effects of medical marijuana on migraine headache treatment and prophylaxis."1
Comments from Migraine Specialists:
Dr. Rob Cowan, Professor of Neurology and Director of the Stanford Headache Program offered his remarks:
I don't have a simple sound bite, because it is not a simple issue, as you know. My clinical experience has been that a significant percentage of my patients who have tried medical marijuana as an abortive have found it useful. However, when used as a preventive (daily use) the experience is that it loses its effectiveness and may result in a rebound phenomenon. I think that the jury is still out on whether the benefit is placebo or not and of course as the article points out, the herb that is dispensed is quite variable and studies looking at specific strains are non-existent. I suspect that, in moderation, it is a reasonable thing to consider when standard treatments are not adequate. It is certainly safer than cutting ones nerves3
Dr. Brian McGeeney, Assistant Professor of Neurology at Boston University School of Medicine and a migraine specialist at Boston Medical Center, said:
The open-minded medical community welcomes more research into cannabinoids. This retrospective review of how patients did after medical marijuana for migraine was encouraging and serves to generate hypotheses about how marijuana may be useful. This does not constitute any manner of proof however, as only proper controlled studies can begin to answer the question. It would be wrong to think that because the subjects did so well it is likely due to the marijuana. We just do not know, without proper controlled studies.4
Dr. David Watson, my migraine specialist and director of the Headache Center at West Virginia University, commented:
Everyone should be interested in the possibility that marijuana based treatments may be shown effective for any and all of the many efficacy claims being made. However, this study does little to nothing to move the evidence needle. Aside from being a retrospective review done in a practice with a financial incentive to show benefit of marijuana for migraine, the data is weak. Over half of the patients seen in the four year period did not return for follow-up. This alone challenges any relevance of the remaining patient data. Who made the diagnosis of migraine and by what criteria?
How is migraine relief defined? Over what time period - two-hour pain free? two-hour relief? 24-hour sustained pain free? And despite creating a data set as favorably as possible for positive outcomes, only 39 percent reported benefit in ANY of the various outcomes reviewed.
Medical uses of marijuana based products should be studied. But this paper is not helpful in furthering the science or getting any closer to the development of meaningful therapeutic options for migraine sufferers.5
Comments and Implications for Patients:
We all want to believe the conclusions of studies when they show a treatment to be helpful for migraine. Thus, we want to believe the conclusion of this study, but it's simply not supported. Their two main data points were decreased migraine frequency in 19.8 percent of the patients whose records were reviewed and 11.6 percent of migraine attacks aborted by medical marijuana. In well designed and implemented double-blind, placebo-controlled clinical trials of medications, it's not at all unusual to see a placebo effect of up to 30 percent. This study had no placebo control to look at, and their two main data points were below what's considered to be a "normal" placebo effect rate.
Another issue is that the researchers included data from some patients who were using medical marijuana before the trial period, invalidating any comparisons between them and patients who were not using medical marijuana before the trial period.
Under other circumstances, I'd say that this study is interesting, but we need to see double-blind, placebo-controlled studies that replicate their results before accepting their conclusion as valid. Unfortunately, given the legal issues surrounding marijuana, such trials cannot be conducted. Therefore, rather than considering this to be preliminary clinical trial data, I consider it anecdotal evidence at best.