Testing a Non-Deceptive Placebo Intervention for Subclinical Depressive Symptoms

Subclinical depression - depressive symptoms that fall below the threshold for major depressive disorder - is common in young adults and predicts later depressive episodes, yet it often goes untreated. This study tests whether a brief, remotely delivered non-deceptive (open-label) placebo intervention reduces subclinical depressive symptoms over approximately two weeks. Participants aged 18-30 living in Ohio, with PHQ-8 scores in the 5-9 range, are randomly assigned to one of three groups: a non-deceptive placebo group, a blinded control group, or an unblinded control group. All participants complete three remote sessions over 16-18 days and complete the same assessments on the same schedule. Participants in the non-deceptive placebo group additionally receive psychoeducation about placebo effects and placebo pills that are explicitly described as containing no active ingredients, which they take twice daily for two weeks. Participants in the unblinded control group are told they have been assigned to a control condition. Participants in the blinded control group are not told their group assignment until debriefing at the end of the study. The study has two aims. The first is to estimate the effect of the non-deceptive placebo intervention on depressive symptoms and related outcomes. The second is methodological: to determine whether telling control participants that they are in a control group changes their outcomes, and therefore whether the choice of control condition systematically biases estimates of non-deceptive placebo effects.