To understand this paradox, researchers at Washington State University compared two doses of THC to a placebo, while measuring several indicators of stress. The result is far from a simple “cannabis = relaxation”.
They feel less stressed… even with a placebo
The experience brought together 120 regular cannabis usersrandomly distributed into three groups: placebo, 20 mg THC Or 40 mg THC. Neither the participants nor the researchers knew who received what.
Before taking, then 5 minutes and 60 minutes laterthe scientists assessed their perceived stress and several physiological reactions: salivary cortisol, heart rate, heart variability and electrical conductance of the skin.
First result, particularly striking: participants in all three groups reported feeling less stressedincluding those who had received the placebo. The researchers therefore found no evidence that cannabis reduced perceived stress more than the placebo.
“One measure of stress is simply asking people: How stressed do you feel right now? What’s interesting is that this often doesn’t really correspond to the physiological indicators of stress that we measure.”explains Carrie Cuttler, psychologist and lead author of the study.
The effect of expectations was even particularly marked: a participant in the placebo group interrupted the inhalation, convinced that the effects were too strong.
Cortisol drops, but the heart speeds up
When researchers looked at what was happening in the body, the picture became more complicated.
- THE cortisolone of the main hormones involved in the stress response, decreased after taking THC, with a greater drop at 40 mg. But it then rose relatively quickly;
- There skin conductance also decreased under THC, which corresponds to less activation of the nervous system;
- But simultaneously, heart rate increasedparticularly with the 40 mg dose. As for heart rate variability, it did not differ significantly between the groups.
The body therefore does not seem to respond to cannabis like a block. Some signals decrease, others remain stable or increase.
“It’s not a coherent story.”
For researchers, it is precisely this gap that deserves attention. The different indicators of stress measured in the study were poorly correlated with each other: a variation in cortisol did not necessarily correspond to a variation in felt stress, heart rate or skin activity.
“It’s not a coherent story. Cannabis has different effects depending on which outcome you’re looking at.”summarizes Carrie Cuttler.
The study therefore suggests that it is simplistic to simply speak of a “relaxing” effect of cannabis. The feeling of calm may be real, but it does not necessarily reflect all of the physiological reactions that occur simultaneously.
A placebo effect that counts, but does not explain everything
The authors believe that consumers’ expectations can play an important role in their perception of stress.
“Consumers should understand that even if they feel like cannabis reduces their stress, much of this could be a sort of placebo effect, related to their expectations of what they think cannabis will do.”.
This finding does not mean that participants are “imagining” their relief. Rather, it shows that feeling better and showing fewer physiological signs of stress are two different things.