In most cannabis trials against pain, people who take a placebo tend to report about the same level of pain relief as those who take the psychoactive substance. However, according to a new study led by Karolinska Institute in Sweden, such studies receive significant media coverage, regardless of their clinical outcome.
“We see that cannabis studies are often described in positive terms in the media regardless of their results,” explained study lead author Filip Gedin, a postdoctoral researcher in Clinical Neuroscience at Karolinska. “This is problematic and can influence expectations when it comes to the effects of cannabis therapy on pain. The greater the benefit a treatment is assumed to have, the more potential harms can be tolerated.”
The researchers analyzed 20 clinical studies involving over 1,500 participants, in which the effects of cannabis on pain relief were compared to those of a placebo. In most of these studies, pain was rated as being significantly less intense after treatment with a placebo. Moreover, no clear difference in pain reduction between cannabis and placebo was identified. “There is a distinct and clinically relevant placebo response in studies of cannabis for pain,” Dr. Gedin reported.
In a next step, the scientists examined the connection between the magnitude of the therapeutic effect shown by these studies and the coverage they received in media and academic journals. The analysis included 136 news items in both traditional and online media, and was categorized as positive, negative, or neutral, depending on how the scientific findings concerning the effectiveness of cannabis as a treatment for pain were presented.
The investigation revealed that the cannabis studies received much greater media attention than other published studies, and the coverage was substantial regardless of the magnitude of the placebo effect. Moreover, there was no observed link between the proportion of positively described news about the studies and the effects they reported.
“Placebo contributes significantly to pain reduction seen in cannabinoid clinical trials. The positive media attention and wide dissemination may uphold high expectations and shape placebo responses in future trials, which has the potential to affect the outcome of clinical trials, regulatory decisions, clinical practice, and ultimately patient access to cannabinoids for pain relief,” the authors concluded.
The study is published in the journal JAMA Network.
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