Breathing and Decision-Making (ProlEx-Context)

Overview

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.

Interventions

• 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.

Primary outcome measures

• Risk propensity [Time frame: On day 1.]
• Task-related BOLD Signals [Time frame: On day 1.]
• Structural T1-weighted MRI [Time frame: On day 1.]
• Relative amplitude of the respiratory signal [Time frame: On day 1.]
• Respiration rate [Time frame: On day 1.]
• Heart rate [Time frame: On day 1.]
• Heart-rate variability [Time frame: On day 1.]
• Gastric myoelectrical activity [Time frame: On day 1.]
• Tonic skin conductance [Time frame: On day 1.]
• Event-related skin conductance responses [Time frame: On day 1.]

Secondary outcome measures (12)

• Response Times [Time frame: On day 1.]
• Self-reported levels of stress [Time frame: On day 1.]
• Self-reported levels of tension [Time frame: On day 1.]
• Self-reported levels of heart feeling [Time frame: On day 1.]
• Self-reported levels of stomach feeling [Time frame: On day 1.]
• State and Trait Anxiety questionnaires [Time frame: On day 1.]
• Affect questionnaire [Time frame: On day 1.]
• Depression questionnaire [Time frame: On day 1.]
• Personality questionnaire [Time frame: On day 1.]
• Impulsivity questionnaire [Time frame: On day 1.]
• Self-control questionnaire [Time frame: On day 1.]
• Behavioral inhibition and activation questionnaire [Time frame: On day 1.]

Eligibility criteria

Inclusion criteria

• 18- 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)

Exclusion criteria

• 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)
• Professionally or privately being involved in the processing of ferromagnetic metals
• Large tattoos (whole limbs)
• Pregnancy
• Wearing an intra-uterine device
• Having tinnitus
• Extensive lung function (e.g. apnoe diver, singer, professional musician with lung-involving instruments)
• Previous participation in the ProlEx-MRI study (the precursor to the current study)

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Open label

Primary purpose

Basic science

Study locations

Center list to be confirmed — check the primary protocol.

Publications

• Freitag, C. M., Retz-Junginger, P., Retz, W., Seitz, C., Palmason, H., Meyer, J., ... & von Gontard, A. (2007). Evaluation der deutschen version des Autismus-Spektrum-Quotienten (AQ)-die Kurzversion AQ-k. Zeitschrift für klinische Psychologie und Psychotherapie, 36(4), 280-289.
• Döring, N., & Bortz, J. (1993). Psychometrische Einsamkeitsforschung: Deutsche Neukonstruktion der UCLA Loneliness Scale. Zeitschrift für Klinische Psychologie, 22(3), 224-233.
• Lang, G. & Bachinger, A. Validation of the German Warwick-Edinburgh Mental Well-Being Scale (WEMWBS) in a community-based sample of adults in Austria: a bi-factor modelling approach. J Public Health 25, 135-146 (2017).
• Grimm, J. State-trait-anxiety inventory nach Spielberger. Deutsche Lang- und Kurzversion. Methodenforum der Universität Wien: MF-Working Paper (2009).
• Schwarzer, R., Bäßler, J., Kwiatek, P., Schröder, K., & Zhang, J. X. (1997). The assessment of optimistic self-beliefs: comparison of the German, Spanish, and Chinese versions of the general self-efficacy scale. Applied Psychology, 46(1), 69-88.
• Fliege, H., Rose, M., Arck, P., Levenstein, S. & Klapp, B. F. (2001). Validierung des "Perceived Stress Questionnaire" (PSQ) an einer deutschen Stichprobe. Diagnostica, 47, 142-152.
• Janke, S., & Glöckner-Rist, A. (2014). "Deutsche Version der Positive and Negative Affect Schedule (PANAS)" in Zusammenstellung sozialwissenschaftlicher Items und Skalen, GESIS (Mannheim, Germany).
• Strobel, A., Beauducel, A., Debener, S., & Brocke, B. Eine deutschsprachige Version des BIS/BAS-Fragebogens von Carver und White. [A German version of Carver and White's BIS/BAS scales.]. Zeitschrift für Differentielle und Diagnostische Psychologie 22, 216-227 (2001).

Identifiers

NCT: NCT07505641 · ProlEx-Context · 88/2025 107/2025

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗