Interactions Between Placebo Effects and Mindful Awareness State

Not Applicable

Not yet recruiting

• Conditions: Placebo Effect; Mindfulness; Pain; Transcranial Direct Current Stimulation (tDCS)

• Registration Number: NCT07108101
• Lead Sponsor: Trustees of Dartmouth College

Brief Summary

In this experiment,the investigators study the effects of interpersonally induced placebo effects and a mindful awareness induction on negative affect. Specifically, it will be examining the effects of interpersonally induced placebo effects (sham tDCS vs. control) and a mindful awareness induction (mindful state vs. control), as well as their interaction. Each group will undergo fMRI scanning and physiological recording will performing the Multimodal Negative Affect Task (MNAT).

Detailed Description

This study aims to investigate the effects of interpersonally induced placebo effects and a mindful awareness induction on negative affect. The study will involve 120 participants recruited from the Dartmouth College community, aged between 18 and 55, with an equal distribution of 60 males and 60 females. Participants will be assigned to the role of "patient" and will undergo fMRI scanning and physiological recording while performing the Multimodal Negative Affect Task (MNAT).

The study design follows a 2 x 2 factorial design, examining the effects of interpersonally induced placebo effects (sham tDCS vs. control) and a mindful awareness induction (mindful state vs. control), as well as their interaction. A follow-up transfer assessment (1 week follow-up, session 2) will be conducted to examine the effects of the mindful state on verum motor tDCS stimulation. The participants will be randomly assigned to either the Mindfulness group or the No-mindfulness group, with 60 participants in each group and two sessions for each participant.

In session 1, participants in the Mindfulness group will undergo a Mindful State Induction procedure aimed at promoting safety, relaxation, and receptivity. This induction procedure consists of two stages. In the first stage, participants will receive education about the brain's connection to and regulation of the body, emphasizing the endogenous brain regulatory capacities. The second stage involves a hypnotic induction of a relaxed state of receptivity using the Stanford Hypnotic Induction Profile (HIP) test of hypnotizability. This stage includes reclining the participant, suggesting that they are always in control, and making somatic suggestions to deepen the receptive state. A guided body scan, derived from mindfulness meditation, will further deepen the induced receptive state.

In contrast, participants in the No-mindfulness group will go through comparable stages but with different instructions. In the first stage, they will receive education about pain and affect as protective processes of the body. In the second stage, they will be seated in an upright, alert posture and receive suggestions to focus on the task and suppress attention to the body.

During the transfer test, conducted in a second fMRI session one week later, we will assess transfer to verum, open-label motor-cortex tDCS in an off-on-off design (both groups), with no explicit mindful state induction. No MRI data will be acquired during tDCS to avoid MR artifacts. We will also assess spontaneous use of strategies, including self-regulation and spontaneous adoption of states of mindful acceptance, and test whether these differ across groups.

The analysis will involve assessing self-report measures, fMRI signatures, and autonomic reactivity to cues and task stimuli, similar to Experiment 1. The analysis will also explore the mediating role of interpersonal response (IPIX scores) and participants' initial responses to placebo.

The researchers plan to control for sex, age, and experimenter effects in all analyses and will test for potential biological sex differences, disaggregating the data if necessary. MRI data will not be acquired during tDCS to avoid artifacts, and the study is not designed to directly compare placebo tDCS with verum tDCS. However, it aims to investigate interpersonal and suggestion-related contributions to open-label treatment responses, providing a foundation for future studies on tDCS and its interactions with placebo effects.

Study Timeline

• Study First Submitted: 2025-05-25
• Status Verified: 2025-07
• Study First Submitted QC: 2025-07-31
• Last Update Submitted: 2025-07-31
• Study First Posted: 2025-08-06
• Last Update Posted: 2025-08-06
• Study Start: 2026-06-01
• Primary Completion: 2028-06-01
• Study Completion: 2028-11-30

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 120

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Primary Outcome Measures

Name	Time	Method
Pain Ratings	3-10 sec post-stimulus throughout testing sessions, with all sessions complete within 1 month	Participants report subjective pain experience after each trial on a well-validated Generalized Linear Magnitude scale (GLMS) with anchors of "No pain" and "Most intense pain imaginable". Raw units are on a 0-180 scale.
Subjective fear ratings	3-10 sec post-stimulus throughout testing sessions, with all sessions complete within 1 month	Participants report subjective fear experience after each trial on a well-validated Generalized Linear Magnitude scale (GLMS) with anchors of "No fear" and "Most intense fear imaginable"
Cognitive effort ratings	3-10 sec post-stimulus throughout testing sessions, with all sessions complete within 1 month	Participants report cognitive effort experience after each trial on a well-validated Generalized Linear Magnitude scale (GLMS) with anchors of "No effort" and "Most effort imaginable"

Secondary Outcome Measures

Name	Time	Method
Electrodermal autonomic responses to painful heat, fear-related images and cognitive effort.	Peri-stimulus throughout testing sessions, with all sessions complete within 1 month	Skin conductance (EDA) is recorded continuously throughout test sessions and per-stimulus amplitude of canonical stimulus-locked EDA responses is reported in microsiemens (uS). Higher values indicate a higher EDA response.

Trial Locations

Locations (1)

Dartmouth College; 🇺🇸 Hanover, New Hampshire, United States