By Pat Anson, Editor
Experts tell us that women are more likely to experience chronic pain than men, feel pain more intensely, and are more likely to be undertreated for pain than men are.
The gender gap in pain grew a little wider this week with a new study, published in Drug and Alcohol Dependence, which claims women get far less pain relief from smoking marijuana than men do.
"These findings come at a time when more people, including women, are turning to the use of medical cannabis for pain relief," said lead author Ziva Cooper, PhD, associate professor of clinical neurobiology at Columbia University Medical Center. "Preclinical evidence has suggested that the experience of pain relief from cannabis-related products may vary between sexes, but no studies have been done to see if this is true in humans."
Cooper and her colleagues conducted two double-blinded, placebo-controlled studies that looked at the analgesic effects of cannabis in 42 healthy recreational marijuana smokers – half of them men and half women.
All smoked marijuana at least four times a week prior to enrolling in the study. Participants were excluded if they had pain.
After smoking the same amount of cannabis or a placebo, the participants immersed one hand in a cold-water bath until the pain could no longer be tolerated. Following the immersion, the participants answered a short pain questionnaire.
Among those who smoked cannabis, men reported a significant decrease in pain sensitivity and an increase in pain tolerance. But the women who smoked cannabis did not experience a significant decrease in pain sensitivity, although they did report a small increase in pain tolerance shortly after smoking.
No gender differences were found in how intoxicated the participants felt or how much they liked the effect of cannabis.
“These results indicate that in cannabis smokers, men exhibit greater cannabis-induced analgesia relative to women,” said Cooper. “Sex-dependent differences in cannabis’s analgesic effects are an important consideration that warrants further investigation when considering the potential therapeutic effects of cannabinoids for pain relief.”
A marijuana advocate and caregiver for patients in Rhode Island said she was shocked by the study findings.
"This study concerns me that some women will read this and not even try the most magical pain relief out there," said Ellen Lenox Smith, a columnist for Pain News Network. "We have never, in the nine years of growing for myself and as caregivers for patients, ever had a time that this was not successful because of one's sex. We have had equal amounts of men and women and the only person that did not have success was an elderly woman that was not able to follow the directions due to her anxiety of using it. That was due to the stigma from society, not the product."
Do women really respond differently to marijuana or is there a flaw in the study itself?
Previous research has found that women respond differently to the cold water test and have far less tolerance for pain induced by cold water immersion than men.
“Most studies have used some form of the cold pressor test in which subjects immerse their arm or hand in circulating cold water for a defined period of time, and their results support the hypothesis that cold pain sensitivity is more pronounced in females,” researchers reported in a 2009 review of nearly two dozen studies that used the cold water test. “Based on the present set of studies, it appears that sex differences in cold pain are consistent, particularly for suprathreshold measures such as tolerance and pain ratings.”
The Columbia University study was funded by the U.S. National Institute on Drug Abuse. Ziva Cooper also received salary support from Insys Therapeutics, which is developing cannabis-based drugs.