Background: Cannabidiol (CBD), a nonpsychoactive cannabinoid found in the cannabis plant, has gained interest for its purported stress- and anxiety-reducing effects. However, the mechanisms underlying these effects remain unclear. Our group previously found that CBD expectancy alone resulted in lower state anxiety (vs. CBD-free expectancy) among those who strongly believed it was helpful for such purposes, in addition to influencing physiological measures (i.e., heart rate variability). Aims: Using data collected as part of this previously published larger study, we aimed to explore the extent to which CBD expectancy alone impacts cortisol in the context of a laboratory stressor. Methods: A sample of 43 healthy adults (23 female) participated in one orientation and two experimental laboratory sessions. They received the same oil (CBD-free) during both experimental sessions but were told they received CBD oil in counterbalanced order in one of their sessions. Participants then engaged in a laboratory stressor (the Maastricht Acute Stress Test; MAST) and salivary cortisol samples were collected throughout [T1: baseline; T2: 90-min postabsorption (PA); T3: poststress (0-PS); T4: 10-min poststress (10-PS); T5: 30-min poststress (30-PS)]. Linear marginal models were used for analyses. Results: Findings indicated that a physiological stress response was elicited in the context of the MAST, which is consistent with what has been reported previously. Interestingly, while cortisol levels were significantly lower in the CBD expectancy condition (vs. CBD-free) immediately following the MAST (0-PS) and 10-min later (10-PS), this effect seems to be largely driven by males, evidenced by a three-way interaction. Cortisol levels did not reliably vary across expectancy conditions at any other time point. Conclusion: Overall, these results suggest that CBD expectancy appears to blunt cortisol in anticipation of a stressor, particularly in males. Findings suggest that it is important to consider the impact of drug-related expectations when assessing CBD-related effects on stress-related processes.
Keywords: biological sex; cannabidiol (CBD); cortisol; expectancies; stress; stress anticipation.