A recently-published report in the Canadian Medical Association Journal suggests that smoking marijuana, or “pot,” can reduce symptoms of pain, improve mood, and aid sleep in patients with chronic neuropathic pain. However, this study actually provides only a smidgen of valid evidence and much more research is needed before patients are advised to “light up” for better pain relief.Investigators from McGill University in Montreal, Quebec, conducted a randomized, controlled, cross-over trial to determine the analgesic effect of smoked marijuana (cannabis) in 21 patients — mean age 45 years, 12 women — all of whom were experiencing chronic post-traumatic or postsurgical neuropathic pain [Ware et al. 2010]. During each cycle, participants inhaled a single 25 mg dose of cannabis 3 times daily for 5 days, followed by a 9-day washout period. The cannabis THC level (marijuana drug potency) for each randomly assigned cycle was either 9.4%, 6%, 2.5%, or 0% (placebo).
Average daily pain intensity (on an 11-point visual analog scale) was significantly reduced by 9.4%-THC cannabis compared with placebo (p=0.023), whereas other levels of THC yielded little added pain relief. Compared with placebo, participants receiving the highest level of THC also reported greater ease in falling asleep, improved sleep quality, and reduced anxiety; however, no other significant differences in mood or quality of life were found at any level of THC. There were assorted reports by participants of psychoactive effects — eg, dysphoria, lack of concentration — but these did not result in any trial dropouts; euphoria or “high” was reported on only 3 occasions throughout the study. Common drug-related adverse events included headache, dry eyes, dizziness, numbness, and cough, some of which may have related to smoke inhalation, whether active drug or placebo (35% of participants had never smoked before).
CONCLUSIONS/COMMENTARY: The researchers concluded that inhaling 25 mg of smoked marijuana with 9.4% TCH content several times a day for 5 days significantly reduced pain intensity in adults with chronic neuropathic pain. However, while the pain reduction was statistically significant, the absolute mean difference in pain scores compared with placebo was modest (difference 0.7, 95% CI 0.02-1.4) and may not be clinically significant. There also were some inconsistencies in data reporting in the published article that add some confusion, and the small number of participants did not lend much statistical power for valid analyses.
Still, this is an important topic because patients with chronic neuropathic pain have relatively few treatment options, such as antidepressants, local anesthetics, anticonvulsants, or opioids, as noted in a recently-reported research review [see our blogpost on this]. It was noted in that review that cannabinoid agents (oral, not smoked) have demonstrated limited effectiveness for neuropathic pain. While many patients with pain smoke marijuana for medicinal purposes and anecdotally report its benefits, there has been very little research aside from laboratory experiments involving small numbers of human volunteers. This present, Canadian, study may be the first to enroll outpatients in this type of research; however, it contributes only a modicum of evidence that cannabis is of clinically significant benefit for neuropathic pain. Much larger, longer-term trials of high-THC-potency marijuana, smoked more frequently, and assessing both efficacy and safety may be warranted, if the adversarial political climate surrounding this drug will permit it.
REFERENCE: Ware MA, Wang T, Shapiro S, et al. Smoked cannabis for chronic neuropathic pain: a randomized controlled trial. CMAJ. 2010(Aug 30); online ahead of print [abstract here]. Full-article PDF was available [here] at the time this blogpost was published.
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A woman who smokes medically prescribed marijuana for post-brain-surgery-induced, chronic trigeminal nerve pain, stood up at the mike after the cannabinoid session at the recent IASP congress, and said that while marijuana use did not decrease the intensity of her face pain, it gave her a rest from caring about it, a space to escape into for cognitive rest from pain's intrusiveness. I thought her statement provided insight to a very interesting, possibly useful, probably overlooked/underinvestigated application: i.e., the pain may NOT change but *caring* about it, does.
Thank you, Ms. Jacobs, for your comment above. In this Canadian study they did measure that marijuana, at the highest dose, did reduce anxiety, which might also be interpreted as a reprieve from worry or "excessive caring." Such anxiolytic properties seem more scientifically appealing than the thought of recommending a drug for users to essentially "zone out." Just my opinion. -- SBL
I think it will likely become important to investigate what 'cognitive resting' might involve. For some it might be a zoning out but for others it might be a chance to use one's cognition in a manner unimpeded, or at least less impeded (think ball & chain), by constant chronic pain. In both those scenarios, some anxiety may still be associated, but may be affecting the same subject in somewhat different ways or in different parts of the brain or through different signaling pathways.
makes me wonder - is the "caring about the pain" the essential issue for chronic pain? i recall when my father had bone cancer that when asked if the morphine was helping "i still feel the pain, i just don't care"
@lucy,'caring about the pain' might just be the central issue in chronic pain.
Maybe:
Detachment from 'caring' --> less anxiety about pain or about being attached to it/having it seem so inescapably attached to oneself --> greater access to smoother physical accomplishment of ADL.
It is known that THC, the active ingredient in cannabis, binds with opiate receptors in the brain. So, it should come as no surprise that the qualitatively higher THC content in this study results in significant pain reduction. That the participants report a feeling of "caring less" about their pain might present an added effect, which should be further studied.
Another area of interest is whether oral THC (Marinol) has the same beneficial effect. Many people today use Marinol off-label for chronic nociceptive and neuropathic pain. An obvious area of interest for future research should be to explore any difference in efficacy between inhaled and ingested THC. A confounding factor might be the dozens of chemicals that enter the bloodstream when cannabis is smoked, compared with the single chemical associated with ingestion (THC). It is possible that some of the added chemicals associated with inhaling the drug are also beneficial to pain relief. And, of course, inhaled THC reaches peak plasma level much more swiftly than ingested THC. Might this alter the patient's perception of the quality of pain relief?
Tens of thousands of people during the past hundred years or so have reported a decrease in pain associated with cannabis intake. This study only reinforces that belief. Unfortunately, this study used a rather small population. While the number of participants, particularly those using the highest THC content remains low, the results still appear statistically significant to some extent. Hopefully, future research will use much larger populations and will attend to the efficacy of oral THC, in addition to the inhaled option.
It would be nice if the United States would take marijuana out of the schedule I clasification so some real down to earth test could be started with some marijuana of a higher grade than what Canada or the United States Government can come up with. I got some from Holland not to long ago that made the stuff the government grow like smoking hay out of the hay field.
Lets get real about this we are dealing with some excruciating pain that low grade marijuana is like trying to pee pee on a forest fire it's not going to cut it. We need some high grade marijuana in a large clinical trial, 25 people WOW! what a test that was. With 70+ Million people suffering I think we could do better than that. Come on people we are suffering out here people eating bullets to escape the pain.
Men on the moon, A joint space station, sending billions of dollars in foreign aid to other countries, When in God's name is someone going to help US? SIGH!!
it always intensified neuropathic pain for me. It actually intensified any pain for me. That's why I stopped using it 22 years ago when i got into recovery. It probably took 5 years for the cravings to end.
Once I became dependent on it, cannabis increased my pain, increased my anxiety, and led to some paranoia.
Although I loved marijuana in my earlier years I had to quit smoking it because it intensified intestinal pain. Maybe it works for some pain and not others? Never had a problem with addiction or cravings, just realised it was causing a problem and stopped. A friend of mine used it exclusivley for back pain, worked for him.
I have neuropathic pain in my legs and feet, for me smoked marijuana works better than morphine for the electrical shooting pain.
Were going to vote on marijuana in a few days in my state. If it passes, I hope to be able to stop my long acting opioids and just use a few instant release for break through pain.
The other advantage to smoked marijuana is I don't have to wait an hour for it to work when I get up in the middle of the night in pain.
I can take a couple puffs, and I'm back in bed in 10 minutes or so. It's also easier during the day to titrate the dose to my pain level.
It's time the federal government allows mor research into marijuana.
i suffer from neuropathic pain every waking second of my life after a very bad eye injury due to a large fishing hook. The pain is so bad my head pounds and my ears ring, it can go for days or weeks. I also cant go out in the sun for very long and am very limited to what i could do. Marijuana stops it dead in its tracks without all the harsh side affects from painkillers. I can now sleep and eat everyday. Marijuana is not for everyone if i smoke it it will help right away but will give me a headache after a hour if i eat a gram to two grams of hash 1 hour before bed i fall asleep right away and wake up normal, hungry and can go the whole day without it or pain. So for me it works.
I smoked marijuana from 1979 until present day, only stopped because my Pain Mgmt dr is now doing drug test. I suffer with chronic, severe neuropathy in my legs/feet and terrible lower back pain. Was operated on in 2004 and have never recovered, I have never damage from an artificial disc replacement surgery(L4 & L5). The pain never stops but when I have smoked hight grade pot and I mean the really good stuff, it most definitely helps with both the lower back pain and the nerve pain. It decreases my pain level, helps me sleep, improves my depression and takes me to a place where "I don't care about the pain anymore." After being in chronic severe pain for over 6 yrs, I would do anything to get relief, instead of smoking pot, I have to take 4 16mg Exalgo pills and they are killing my kidneys and liver.....
With regard to the potency issue, please note that many high grade cannabis strains sold through dispensaries in California are reputed to possess THC concentrations of 15 to 20+ per cent.
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