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Study on the Effects of Yohimbine and Hydrocortisone on Stress and Moral Decisions in Military Personnel

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on understanding how certain medications affect decision-making under stress. The study involves the use of two medications: yohimbine hydrochloride and hydrocortisone. These medications are being tested to see how they influence moral judgment, particularly in situations that mimic an acute stress response, which is a sudden and intense stress reaction that can occur in challenging situations.

The purpose of the study is to observe the effects of these medications on moral judgment in military personnel. Participants will be given either yohimbine, hydrocortisone, or a placebo. The study will monitor how these medications affect the choices made during tasks that measure moral judgment, such as deciding between different ethical options. The study will also look at how these medications impact working memory, impulse control, and risk-taking behavior.

Participants will take the medications in the form of tablets or oral powder, and the study will last for a short period. The goal is to better understand how stress and these medications can influence decision-making processes. This research could provide valuable insights into how stress affects ethical decisions and help develop strategies to manage stress in high-pressure environments.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, eligibility is confirmed based on age and active military status. Participants must be between 18 and 60 years old and actively serving in the military.

  2. Step 2

    Medication administration

    Participants receive medications to mimic an acute stress response. The medications include yohimbine hydrochloride and hydrocortisone, both administered orally.

    Yohimbine hydrochloride is provided in the form of YOCORAL 5 mg tablets. The dosage and frequency are determined by the study protocol.

    Hydrocortisone is provided as Hydrocortison Teva 10 mg, film-coated tablets. The dosage and frequency are determined by the study protocol.

  3. Step 3

    Behavioral tasks

    Participants engage in tasks designed to measure moral judgment. These tasks assess the number of utilitarian, deontological, and compromise choices made.

    Additional tasks evaluate rationality in decision-making, working memory, impulse control, and risk-taking behavior.

  4. Step 4

    Completion of study

    The study is estimated to conclude by May 5, 2025. Participants complete all required tasks and assessments by this date.

Who can join the trial?

3 criteria

  • Must be between the ages of 18 and 59 years old.
  • Must be an active duty military member.
  • Both men and women can participate.

Who cannot join the trial?

9 criteria

  • Individuals who are not within the age range specified for the study.
  • Individuals who are not part of the specified group of military personnel.
  • Individuals who are part of a vulnerable population, which means people who might need special protection or care.
  • Individuals who have any medical condition that could interfere with the study or put them at risk.
  • Individuals who are currently taking medications that might affect the study results.
  • Individuals who have a history of severe allergic reactions to the substances being tested, such as **yohimbine** or **hydrocortisone**.
  • Individuals who are pregnant or breastfeeding.
  • Individuals who have participated in another clinical trial recently.
  • Individuals who are unable to provide informed consent, which means they cannot fully understand the study and agree to participate.
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Investigated drugs

  • Yohimbine

    is a medication that is often used to treat erectile dysfunction and sometimes to help with weight loss. In this clinical trial, it is being used to study its effects on stress and how it might influence the way people make ethical decisions. Yohimbine works by increasing certain chemicals in the body that can lead to increased heart rate and blood pressure, which can mimic the body's natural response to stress.

  • Hydrocortisone

    is a medication that is commonly used to treat inflammation and allergic reactions. It is a type of steroid that can also affect how the body responds to stress. In this trial, hydrocortisone is being used to see how it might change the way people make moral decisions when they are under stress. It works by mimicking the effects of cortisol, a hormone that is naturally produced by the adrenal glands in response to stress.

What is already known about the treatment

  • Yohimbine

    Yohimbine is typically administered orally in tablet form. It is currently being studied for its effects on stress responses and ethical decision-making, particularly in military personnel. The main therapeutic indication is to mimic an acute stress response in humans. At the molecular level, yohimbine works by blocking certain receptors in the brain, which can increase the release of norepinephrine, a chemical that plays a role in stress and alertness. It is classified as an alpha-2 adrenergic receptor antagonist.

  • Hydrocortisone

    Hydrocortisone is usually administered orally or through injection. It is being researched for its impact on stress responses and moral judgment, especially in military settings. The primary therapeutic use in this context is to simulate an acute stress response. On a molecular level, hydrocortisone acts by mimicking cortisol, a hormone that helps regulate stress and immune responses. It belongs to the pharmacological class of corticosteroids.

Investigated diseases

Acute Stress Reaction – Acute Stress Reaction is a psychological condition that occurs in response to a traumatic event. It typically develops within minutes to hours after the event and can last for a few days. Symptoms may include anxiety, confusion, difficulty concentrating, and emotional detachment. Individuals may also experience physical symptoms such as sweating, palpitations, and nausea. The condition is characterized by a temporary disruption in normal functioning. It is a natural response to an overwhelming situation and usually resolves on its own.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-508731-31-01Estimated enrolment100 patientsSponsorUniversitair Medisch Centrum Utrecht

sourced from the EU Clinical Trials Register and site verification

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