NCT07505641

Breathing and Decision-Making (ProlEx-Context)

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 50 (estimated)
• Sponsor: German Institute of Human Nutrition · Academic / Other
• Sex: All
• Age: 18 Years – 40 Years
• Healthy volunteers: Accepted

Summary

The ProlEx-Context study aims to investigate how a slow-paced breathing technique with prolonged exhalation affects decision-making in the context of acute social stress.

Detailed description

The ProlEx-Context study explores how a slow breathing technique with prolonged exhalation can restore decision-making processes after exposure to acute social stress. Method Overview: The methods of the study include a guided breathing exercise (prolonged exhalation vs normal breathing rhythm), exposure to acute social stress, peripheral electrophysiology (respiration, pulse, gastric and cardiac rhythms, skin conductance, pupillometry), salivary cortisol sampling, psychological questionnaires, behavioral tasks and functional brain imaging with fMRI. Participant Overview: An estimated 50 participants will be invited to this within-subject fMRI study and will be blinded to the stress induction component of this study. Time frame: One appointment of approx. 4 hours per person. Procedure Overview: Participants will be invited to the testing site at approximately 4 PM. Upon completion of the preparations and placement inside the MRI, the participants will undergo an adapted virtual Trier Social Stress Test (TSST). After completing the TSST, the participants are asked to perform a risk decision-making task inside the MRI, during which they are displayed a visual cue to assist during guided breathing. The participants perform blocks of either normal breathing or prolonged exhalation breathing during performance of the decision-making task in a randomized cross-over-design. During the task, brain activity and peripheral physiological signals, such as the respiration rate, heart rate, skin conductance and pupil dilation are measured. After completion of the first breathing condition (three blocks) and before the second breathing condition, participants will undergo a second TSST. Before and after each TSST, at baseline and after completion of the decision-making task, salivary samples for cortisol assessment are taken. After completion of the decision-making task, participants will be asked to fill out a battery of psychometric questionnaires and reimbursed for their time.

Conditions

• Breathing Techniques
• Stress Management
• Decision-Making

Interventions

Type	Name	Description
BEHAVIORAL	Instructed Prolonged Exhalation	Participants are required to perform a specific instructed breathing pattern directed by visual cues. The core characteristic is a systematic lengthening of the expiratory phase relative to the inspiratory phase. Specifically, participants are instructed to inhale for 2 seconds and prolong their exhalation to 8 seconds.
BEHAVIORAL	Instructed Individualized Eupnea	Instructed Individualized Eupnea: In this control condition, participants are instructed to match their breath to a visual cue that is calibrated to their own characteristic natural respiratory frequency. This frequency is sampled during representative non-interventional phases of the session to capture the participant's individual baseline eupnea pace within the experimental context.

Timeline

• Start date: 2026-04-01
• Primary completion: 2027-04-01
• Completion: 2027-04-01
• First posted: 2026-04-01
• Last updated: 2026-04-01