More Than Pain Relief: Sustained Cannabis Use Leads to Improved Cognition in Cancer Patients

Cannabis Brain Drugs

According to new research, cannabis use in cancer patients not only reduces pain and improves sleep but also appears to enhance cognitive function over time. The study, one of the first to assess the effects of over-the-counter cannabis products, discovered that consistent use for several weeks led to better cognition, possibly due to pain reduction.

New research indicates that cannabis may alleviate “chemo brain.”

New research from the University of Colorado Boulder reveals that cancer patients employing cannabis to manage their symptoms not only experience reduced pain and enhanced sleep quality, but also enjoy another unexpected advantage: after several weeks of continuous use, they seem to think more clearly.

“When you’re in a lot of pain, it’s hard to think,” said senior author Angela Bryan, a professor of psychology and neuroscience at CU Boulder and a cancer survivor. “We found that when patients’ pain levels came down after using cannabis for a while, their cognition got better.”

The small but groundbreaking study, recently published in the journal Exploration in Medicine, is among the first to assess how cannabis bought over the counter at dispensaries— rather than government-supplied or synthetic cannabis — impacts cancer symptoms or chemotherapy side- effects.

The study also explored the variety of products cancer patients use now that it is legal in most states.

Bringing the lab to the patients

Surveys suggest that as many as 40% of U.S. cancer patients use cannabis, yet only a third of doctors feel comfortable advising them about it.

Studying it is complicated because federal law prohibits university researchers from possessing or distributing cannabis for research unless it’s government-issued or of pharmaceutical grade. As a result, most studies have looked only at prescription products like nabilone or dronabinol (typically prescribed for nausea) or government cannabis strains that tend to be less potent and lack the variety of over-the-counter offerings.

This research team took a different approach.

Bryan collaborated with oncologists at the CU Anschutz Medical Campus to observe 25 cancer patients who used cannabis over two weeks.

After a baseline appointment in which their pain levels, sleep patterns, and cognition were assessed, they were asked to purchase the edible product of their choosing from a dispensary. Choices were surprisingly varied, spanning 18 brands, including chocolates, gummies, tinctures, pills, and baked goods, and contained varying ratios of THC and CBD at a wide range of potencies.

“This tells us that people are open to trying whatever they think might be useful, but there’s just not much data out there to guide them on what works best for what,” said Bryan.

To study acute impacts, researchers drove a “mobile laboratory” (a Dodge Sprinter van sometimes referred to as the “cannavan”) to each patient’s home one day. Participants underwent physical and cognitive assessments in the van, then re-tested in the van after using cannabis in their homes.

After two weeks of sustained use at the frequency of their choice, they also had a follow-up exam.

Within an hour, the study found, cannabis eased patients’ pain significantly while also impairing their cognition and making them feel “high” (the higher the THC content, the higher they felt).

But longer term, a different pattern emerged: After two weeks of sustained use, patients reported improvements in pain, sleep quality, and cognitive function. Some objective measures of cognitive function, including reaction times, also improved.

“We thought we might see some problems with cognitive function,” said Bryan, noting that both cannabis and chemotherapy have been previously associated with impaired thinking. “But people actually felt like they were thinking more clearly.”

The more people’s pain subsided, the more their cognition seemed to improve.

Those who ingested more CBD, a known anti-inflammatory, reported bigger improvements in sleep quality and pain intensity.

While larger controlled studies are needed, the authors say the findings raise an intriguing possibility: While some forms and dosages of cannabis for pain relief may impair thinking short-term, some regimens might improve cognition in the long run by reducing pain.

Personal experience

Bryan had been studying cancer prevention for years and had just begun studying medicinal cannabis use when, in 2017, her work life and personal health collided with a diagnosis of breast cancer.

After surgery and chemotherapy, she looked to cannabis to help ease her pain.

“The doctors were so supportive of what I wanted to do, but they had no idea what to tell me,” she said. “There was just no data.”

Concerned about using opioids, she created her own custom regimen of more potent THC-heavy products when the pain was intense and she could sacrifice some mental sharpness, and milder, CBD-heavy products to keep the pain manageable.

She was not pain-free, but she didn’t take a single opiate during her treatment.

“I was extremely lucky because I had some knowledge about this. Most patients don’t,” she said.

She hopes her research, and more to come, will help people make better decisions.

Reference: “Cannabis use in cancer patients: acute and sustained associations with pain, cognition, and quality of life” by Gregory Giordano, Renée Martin-Willett, Laurel P. Gibson, D. Ross Camidge, Daniel W. Bowles, Kent E. Hutchison and Angela D. Bryan, 26 April 2023, Exploration of Medicine.
DOI: 10.37349/emed.2023.00138

5 Comments on "More Than Pain Relief: Sustained Cannabis Use Leads to Improved Cognition in Cancer Patients"

  1. Clyde Spencer | July 9, 2023 at 11:03 am | Reply

    On the other hand, a number of recent studies have demonstrated a negative link between cannabis use and mental health among those who were otherwise healthy. In most cases, there is a trade off between the beneficial effects of medicine and undesirable side effects. I hope that cannabis users don’t use this recent study as a way to rationalize their addiction.

    • William Niver | July 10, 2023 at 9:04 am | Reply

      “Rationalize their addiction”? Really? Such phraseology suggests a politicized rather than therapeutic agenda. Spencer’s second sentence is a superfluous banality. He concludes his screed with an expression of personal hope, as if we were interested in or swayed by his personal wishlist. Logically distilled, Spencer’s argument becomes: “Some studies support different conclusions,” an assertion both true and unenlightening.

      • Clyde Spencer | July 10, 2023 at 1:33 pm | Reply

        “… an assertion both true and unenlightening.”

        On the contrary. If experiments cannot be replicated, then it strongly suggests that the results of neither pro or con are reliable and the designs and protocols of the experiments need to be examined.

        It appears that I pushed a button with the word “addiction.” You accuse me of having a “politicized” agenda. Actually, I was offering an opinion based on observations of marijuana users over several decades, some I considered friends. It bothered me what they were doing to themselves. What was your motivation for responding so strongly?

        My political position is that society should discourage recreational use of drugs. Because of the ubiquitous side-effects, the use of drugs is only justified when balanced against the net positive effects, such as pain relief. Recreational drug users never accept culpability for the social damage and shootings related to the supply lines. While Libertarians, particularly, are inclined to characterize recreational drug use as a “victimless crime,” it is my opinion that they are rationalizing.

        My father died prematurely of addiction to tobacco. When I was growing up I tried to get him to stop smoking. I’m well acquainted with people, who are addicted to things, rationalizing their behavior.

  2. Totalitarian fool.

  3. Concerned Reader | July 12, 2023 at 8:48 am | Reply


    Subjective cognitive functioning: “an exploratory analysis was conducted to test the association between subjective cognitive functioning (FACT-Cog PCA) and pain interference after two weeks of cannabis use. As can be seen in Figure 4, there was a negative association, such that as pain interference increased, PCA decreased, although this association did not achieve statistical significance”. [i.e. non-significant subjective improvement]

    Objective cognitive functioning: “The Stroop effect on reaction time exhibited a significant linear effect of time (B = 12.93, SE = 6.09, P = 0.04), such that there was a significant increase in the Stroop effect over the course of the acute administration appointment (i.e., performance worsened)”.

    Discussion: “Also consistent with past research, some impairments following acute administration on objective cognitive performance were also observed, such that the Stroop effect on reaction time and error rate for incongruent trials both increased (i.e., got worse)”. This was their objective measure.

    Conclusion: “In this study of legal market edible cannabis products in cancer patients, two weeks of ad libitum cannabis use was associated with improvements in pain intensity and interference, sleep quality and subjective cognitive functioning”.

    Why the study reports a non-significant exploratory analysis alongside their other results in the conclusion should set off red flags for people (risk of bias). I’m all for cannabis as a therapeutic when it is proven safe and effective, but this study does not convince me. It is concerning as well that the key takeaway here is that sustained cannabis use leads to improved cognition in cancer patients.

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