Personalised and standardised wafer-based open-label placebos reduce perceived stress among university students: A...

Open-label placebos (OLPs) are placebos administered transparently, without deception that can nonetheless yield beneficial effects. We tested a novel OLP delivery format-printed edible wafers, with or without individualised coaching-based personalisation, in highly stressed university students.

In this superiority randomised controlled trial, N = 137 highly stressed university students were randomly assigned for three weeks to a personalised OLP (personalised printed image, label, desired effects) a standardised OLP (standardised for stress reduction), or a waitlist control. The primary objective was to test whether the personalised OLP reduces perceived stress compared to waitlist. Secondary objectives included examining whether the standardised OLP also improves outcomes relative to control and whether personalisation yields incremental benefits. Assessments were conducted at baseline, post-intervention, and at a three-month follow-up. The primary outcome was perceived stress; secondary outcomes included anxiety, depression, sleep, well-being, and life satisfaction; moderators were treatment expectancy (TE) and general self-efficacy (GSE).

Both OLP arms reduced perceived stress vs. waitlist; these effects were maintained at follow-up. Anxiety decreased only in the personalised arm. The OLP arms did not differ significantly. In the standardised arm, lower GSE predicted larger depressive-symptom reductions and higher TE predicted greater well-being gains (vs. waitlist).

Wafers may be a versatile OLP delivery method with potential for mechanism-guided refinement and targeted personalisation in preventive and clinical contexts.

https://osf.io/8afdz.