Masking Influences: A Systematic Review of Placebo Control and Masking in Psychedelic Studies
Journal of Psychoactive Drugs November 6, 2024 Aleksandra Barstowe, Petri J Kajonius 8 citations
A systematic review of nine studies on psychedelic-assisted therapy found that masking success was rarely reported and almost 78% of the studies had at best poor masking. Among active placebo studies, 60% showed large effect sizes, and among inactive placebo studies, 75% showed large effect sizes. Masking influences, including benign unmasking, cannot be excluded. Therefore, the efficacy of psilocybin, ayahuasca, or LSD is only one possible interpretation of large positive changes in symptoms for conditions like alcohol use disorder, anxiety, depression, and treatment-resistant depression. The authors recommend improving masking procedures and considering alternative trial designs.