Miami University
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.
Non-deceptive (open-label) placebos have been shown to reduce negative emotion, stress, anxiety, and depressive symptoms across a range of nonclinical samples. Because the intervention requires explicitly telling participants that the pills contain no active ingredients, participants cannot be blinded to the intervention. This creates an unresolved methodological problem: there is no consensus on the appropriate comparison condition. Some trials use unblinded assessment-only controls, which prioritize transparency but may introduce negative expectancy or demoralization and inflate apparent int…
Inclusion Criteria: * Age 18 to 30 years * Native English speaker * Currently resides in the state of Ohio * PHQ-8 score of 5 to 9 at screening * Reliable daily access to the internet * Willing to provide a mailing address to receive study materials * Willing to participate in Webex sessions with a working microphone and webcam * Willing to complete surveys over a 16- to 18-day period * Willing to receive weekly email or text reminders Exclusion Criteria: * PHQ-8 score greater than 9 or less than 5 at screening * Currently pregnant or breastfeeding * Current clinical diagnosis of anxiety, d…
Participants are explicitly informed that they are in a study of placebo effects and that the pills they receive contain no active ingredients. They receive psychoeducation about placebo effects and open-label placebo tablets (Zeebo Effect LLC; microcrystalline cellulose with a small amount of vegetable-grade stearate), mailed in advance, to be taken twice daily for approximately two weeks, along with a brief daily pill-tracking survey.