6.1.6 Blinding and expectancy bias
The issue of blinding, blinding procedures, and blinding failures in psychedelic trials has received considerable attention in the literature.136 While expectancy bias remains an issue for all clinical trials, expectancy bias has been well documented in the pain literature and should be thoughtfully considered in future trial designs around pain and psychedelics.137 Systematic reviews of the RCTs of psychedelics have illustrated that many trials have used various forms of placebo groups including placebo control groups, inert placebo control, or active placebo control, or both, but there is room to improve on quality and blinding assessment and blinding failure in these trials.138 Blinding integrity tools in the context of psychedelic micro-dosing studies have also been recently developed, as well as recommendations to improve blinding issues in psychedelic trials.139 The impact of preparatory sessions on expectancy, as well as the set and setting and other controllable factors in psychedelics sessions, should be also thoughtfully considered as possible factors influencing outcomes.140
Specific safety considerations in psychedelic trials for those with pain and/or OUD