does marijuana help with nerve pain

Could Pot Help with Nerve Pain?

— Functional imaging suggests THC disrupts pain-associated network connectivity

by Judy George, Contributing Writer, MedPage Today September 5, 2018

Marijuana’s psychoactive component, delta-9-tetrahydrocannabinol (THC), was linked to reduced neuropathic pain and corresponding functional brain changes, researchers reported.

In a small randomized, double-blind, placebo-controlled trial, THC-induced analgesia correlated with a reduction in functional connectivity between the anterior cingulate cortex and the sensorimotor cortex in patients with chronic radicular nerve pain, reported Haggai Sharon, MD, of the Tel Aviv Medical Center in Israel, and colleagues in Neurology.

Graph theory analyses also showed reduced network connectivity in areas involved in pain processing — specifically in the dorsolateral prefrontal cortex. The connectivity changes correlated with less pain.

“We found a reduction in the functional connectivity, a major measure of brain networking, between brain areas that process aspects of sensation to those that process aspects of emotion and cognition in pain,” Sharon told MedPage Today. “This may mean that the pain-relieving effects of cannabis are mediated by a breakdown of the pain experience, rather than just influencing pain sensation.”

Previous research indicated that THC reduced experimentally induced pain in healthy participants and that this analgesic effect correlated with reduced activity of the anterior cingulate cortex. The anterior cingulate cortex has been shown to be densely populated with cannabinoid-1 receptors which THC activates, Sharon and co-authors noted.

In this study, 15 young men with chronic lumbar radicular neuropathic pain participated in a randomized, double-blind, placebo-controlled trial with a crossover design. The average age of the patients was 33.3; they had medium to high chronic pain — over 40 on a 100-point visual analog scale (VAS) — and no other known comorbidities. The researchers excluded women from the trial because evidence suggested that menstrual hormonal fluctuations may alter pain sensitivity.

Before treatment, participants had a clinical evaluation including rating pain on a 0-100 VAS. They had an fMRI scan in a resting state, and then received sublingual THC oil or placebo oil (0.2 mg/kg, average THC dosage = 15.4 mg).

The resting state scan lasted 6 minutes, and patients were instructed to keep their eyes closed and relax, but not sleep. There was then a second fMRI scan about 2 hours after the drug or placebo was administered.

Nine patients received THC in one session and placebo in a second session; six patients received treatment in the reverse treatment order. Sessions were separated by at least a week in order to allow for a washout period (average weeks interval = 2.9).

On average, patients rated their pain level at 53 on the VAS at baseline. Two hours after using THC, patients rated their pain levels at an average of 35, compared with an average of 43 for placebo.

The extent of individual pain relief was associated with reduced functional connectivity between the anterior cingulate cortex and the sensorimotor cortex. “The higher the positive functional connectivity at baseline, the more benefit was gained from THC administration,” the authors noted.

They reported decreases in the right dorsolateral prefrontal cortex cluster and in the chronic pain network, which also were associated with pain reduction. “These measures show that, on average, the whole network has become locally less connected, and in particular, the right dorsolateral prefrontal cortex is less connected to it.”

Larger studies need to confirm the findings, Sharon noted, and research is needed to see whether a combination of THC and cannabidiol is superior to THC alone, as some studies of cancer pain patients have shown. Future work, the researchers said, should include women and should be expanded to other chronic pain conditions to determine whether the results are unique to neuropathy.

This project was supported by Yahel Foundation, Recanati, New York, and by the Ministry of Science, Technology, and Space.

The authors reported having no disclosures relevant to the manuscript.

Functional imaging suggests THC disrupts pain-associated network connectivity

Marijuana May Help Ease Nerve Pain

But evidence for using pot to treat other types of pain or post-traumatic stress remains inconclusive

By Randy Dotinga

HealthDay Reporter

MONDAY, Aug. 14, 2017 (HealthDay News) — Marijuana may be slightly effective at reducing chronic nerve pain known as neuropathy. But there’s little evidence on whether or not pot helps treat other types of pain or post-traumatic stress disorder (PTSD), a pair of new studies suggests.

The findings on neuropathy “fit generally well with what we know,” said Dr. Sachin Patel of the Vanderbilt Psychiatric Hospital in Nashville. Patel wrote a commentary accompanying the review in the Aug. 15 online edition of Annals of Internal Medicine.

Medical marijuana is legal in almost all states and the District of Columbia for certain medical purposes. Some states may have laws that haven’t yet been implemented, according to NORML, a pro-marijuana legalization group.

But research into the medical uses of marijuana remains controversial. Plus, it’s difficult for scientists to study the drug because it is illegal on the federal level.

However, some research has found positive results. Earlier this year, the National Academy of Sciences released a report saying there is conclusive or substantial scientific evidence that marijuana is effective at treating chronic pain, calming muscle spasms caused by multiple sclerosis, and easing nausea from chemotherapy.

The new reviews into pain and PTSD were commissioned by the U.S. Department of Veterans Affairs. The department refused to allow the authors of the reviews to be interviewed to discuss the findings.

Curt Cashour, a spokesman for the department, declined to provide any comment about the reviews.

However, Cashour did provide a written statement with a comment from David Shulkin, the secretary of the Department of Veterans Affairs. The statement said the VA system will not prescribe medical marijuana although “there may be some evidence that this is beginning to be helpful.”

For the review of research into chronic nerve pain and marijuana, the researchers examined 27 studies. The investigators determined that there’s “low strength” evidence that marijuana can help nerve pain. But there’s just not enough reliable research to come to a conclusion about whether marijuana is useful for other types of pain, the study authors determined.


The researchers also looked at 32 studies and 11 reviews of research on side effects. They noted several potential risks of marijuana use such as car accidents, psychotic symptoms and “short-term cognitive impairment.”

However, the review noted that research into risks and side effects is limited.

The researchers said their findings may have “limited applicability to older, chronically ill populations and patients who use cannabis heavily.”

Paul Armentano, deputy director of NORML, said the review findings are consistent with other research reviews. He added that the findings are also consistent with “anecdotal reports of patients, many of whom are seeking a safer alternative to the use of deadly opioids. And it is inconsistent with the federal government’s classification of the marijuana plant as a schedule I controlled substance with ‘no currently accepted medical use in treatment in the United States.’ “

In the second review, researchers looked at three studies and two reviews of marijuana as a treatment for PTSD. The investigators found only a very low level of research. In addition, they said, the research had a “medium- to high-risk of bias.”

There’s no way to come to conclusions based on the few studies currently available. But “several ongoing studies may soon provide important results,” the study authors wrote.

Why is there so little research into medical marijuana?

“Much of the lack of evidence may have to do with difficulty accessing cannabis and funding for clinical studies,” Patel said.

NORML’s Armentano said anti-pot laws and politics have “greatly impeded researchers’ ability to conduct the sort of robust, large-scale, prolonged clinical trials that are typically associated with eventual U.S. Food and Drug Administration drug approval.”

Armentano added that most large studies are funded by pharmaceutical companies trying to get a drug to market.

Patel advised patients to be cautious about medical pot.

“Just because states list certain conditions for which medical cannabis can be prescribed does not mean there is strong or rigorous scientific data supporting its use,” he said.

Patel advised doctors to “follow the data and inform patients about the state of the evidence. Make sure patients are aware of potential benefits, but also potential harms.”

But evidence for using pot to treat other types of pain or post-traumatic stress remains inconclusive