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