Breathing and Decision-Making (ProlEx-Context)

NCT07505641 | Not Yet Recruiting

• 2 other identifiers: ProlEx-Context88/2025 107/2025
• Study Type: interventional
• Target: 50
• Locations: 0 countries
• Sites: N/A

Brief 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.

Conditions

Breathing Techniques; Stress Management; Decision-Making

Outcome Measures

Primary Outcomes (12)

• Risk propensity

  The dependent variable will be trial-wise gamble acceptance (accept vs. reject of a 50% gamble), which will be mainly analyzed using a binomial generalized linear mixed-effects model (GLMM) to compare the Prolonged Exhalation and Eupnea conditions under acute stress.

  On day 1.

• Task-related BOLD Signals

  Task-related changes in blood-oxygen-level-dependent (BOLD) signals measured using functional magnetic resonance imaging (fMRI).

  On day 1.

• Structural T1-weighted MRI

  High-resolution T1-weighted structural images measured using magnetic resonance imaging (MRI).

  On day 1.

• Relative amplitude of the respiratory signal

  Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.

  On day 1.

• Respiration rate

  Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.

  On day 1.

• Heart rate

  Task-based and resting-state heart rate, measured with ECG

  On day 1.

• Heart-rate variability

  Task-based and resting-state heart-rate variability, measured with a three-point electrocardiogram (ECG)

  On day 1.

• Gastric myoelectrical activity

  Resting-state and task-based gastric myoelectrical activity, measured using cutaneous electrogastrography (EGG).

  On day 1.

• Tonic skin conductance

  Tonic task-based and resting-state electrodermal activity, measured with EDA electrodes

  On day 1.

• Event-related skin conductance responses

  Phasic electrodermal activity, measured via electrodermal activity (EDA) electrodes

  On day 1.

• Salivary Cortisol Levels

  Concentration of cortisol in saliva (measured in nmol/L). This indexes the HPA-axis response to the Trier Social Stress Test (TSST). We will compare the cortisol trajectory

  On day 1.

• Pupil dilation

  Task-based and resting-state pupil dilation, measured via eye-tracking

  On day 1.

Secondary Outcomes (22)

• Response Times

  On day 1.

• Self-reported levels of stress

  On day 1.

• Self-reported levels of tension

  On day 1.

• Self-reported levels of heart feeling

  On day 1.

• Self-reported levels of stomach feeling

  On day 1.

Study Arms (2)

Prolonged Exhalation Breathing

EXPERIMENTAL

Participants are required to perform a specific voluntarily controlled 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 Prolonged Exhalation

Eupnea Breathing (Normal)

EXPERIMENTAL

Eupnea (Normal breathing) condition: In this control condition, participants maintain their spontaneous respiratory rhythm. The pacing for eupnea is individualized for each participant, based on their natural breathing frequency sampled during representative non-interventional intervals of the session (e.g., baseline or post-stress recovery periods). This ensures the control condition reflects the participant's characteristic physiological state within the experimental context.

Behavioral: Instructed Individualized Eupnea

Interventions

Instructed Prolonged Exhalation BEHAVIORAL

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.

Prolonged Exhalation Breathing

Instructed Individualized Eupnea BEHAVIORAL

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.

Eupnea Breathing (Normal)

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• to 40-year-old men and women
• Consent to participate
• Fluent in German
• Right-handed
• Physically and mentally healthy without regular medication
• Body-mass index of 18-25 kg/m2
• Alcohol consumption of less than 15 glasses a week (equivalent to one glass of wine/beer, a glass of higher-percentage alcohol counts as two glasses of beer)
• No illegal drug consumption in the week previous to the experiment
• No smoking
• No competitive athletes
• Normal day-night rhythm (no shift work)
• Normal vision without required vision correction (i.e., glasses, contact lenses; ability to clearly read texts at a distance of up to 50 cm without vision aids)

You may not qualify if:

• Former or current illnesses of:
• Brain or mind (including anxiety disorders, depression, eating disorders, personality disorders, alcohol, drugs or drug dependence, neurological disorders other than occasional headache, psychiatric or neurological abnormalities)
• Heart or blood circulation
• Lung Diseases
• Other serious past or present medical conditions (for example, metabolic syndrome, diabetes)
• Current medication and medication over a period of two weeks prior to the examination
• Other serious health problems or present strong mental or physical stress
• Current infection or excessive stress
• Missing consent to receive information about incidental findings from the MRI
• Tendency to claustrophobia, dizziness, or panic attacks
• Wearing a non-removable pacemaker, defibrillator, hearing aid, drug pump, neurostimulator or implant with solenoid valve (e.g., artificial bowel outlet)
• Metal parts or implants inside the body, for example, due to surgery or injury with a metallic foreign object (e.g., hip replacements, artificial joints, heart valves, vessel occlusions or dilatations, surgical clips, bone screws or plates, coil, shunts, catheters, electrodes, coils, radiation sources, shrapnel, projectiles, stents)
• Having non-removable metal parts or metal-containing devices on or in the body
• Having ferromagnetic metal parts or implants inside the body (e.g., hip replacements, artificial joints, heart valves, vessel occlusions or dilatations, surgical clips, bone screws or plates, coils, shunts, catheters, electrodes, coils, radiation sources, shrapnel, projectiles, stents)
• Wearing magnetically fixed implants (e.g. amalgam fillings, glass eye)

Sponsors & Collaborators

• German Institute of Human Nutrition: lead

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Study Officials

• Soyoung Q Park, Prof. Dr.

  German Institute of Human Nutrition Potsdam-Rehbruecke

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Soyoung Q Park, Prof. Dr.

CONTACT

+49 033200 88 2510; soyoung.park@dife.de

Wenhao Huang

CONTACT

Wenhao.Huang@dife.de

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: Participants are not informed in advance about the acute social stress induction, but are fully debriefed after completion of the study.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Prof. Dr.

Study Record Dates

• First Submitted: March 13, 2026
• First Posted: April 1, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): April 1, 2027
• Study Completion (Estimated): April 1, 2027
• Last Updated: April 1, 2026

Record last verified: 2025-12