Fluoxetine on Emotional Experience (FLEX) Study

NCT07424781 | Recruiting

• 1 other identifier: MS IDREC 1017147
• Study Type: interventional
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical medicine study is to investigate how does antidepressant fluoxetine modulate anger processing in healthy young people . The main questions it aims is to answer are:

1. 1.How does fluoxetine affect responses to anger-related stimuli such as words, faces, and autobiographical recall?
2. 2.How does fluoxetine influence responses during frustration induction in frustrative non-reward and threat paradigms?
3. 3.Does the effect manifest in physiological markers, including heart rate variability and facial expressions?

Conditions

Depression - Major Depressive Disorder; Irritability; Depression

Keywords

depression; young people; fluoxetine; irritability; anger

Outcome Measures

Primary Outcomes (1)

• Behavioral Measure: Facial Expression Recognition Task (FERT)

  Recognition of angry faces in the Facial Expression Recognition Task

  On the last day of the 7-day treatment

Secondary Outcomes (8)

• Behavioural Measure: The Affordances Task

  On the last day of the 7-day treatment

• Behavioural Measure: Emotional Categorization Task (ECAT)

  On the last day of the 7-day treatment.

• Performance on Carnival Task

  On the last day of the 7-day treatment.

• Subjective Measure: Rest Task

  On the last day of the 7-day treatment.

• Subjective Measure: Anger Memory Recall Task

  On the last day of the 7-day treatment.

Study Arms (2)

fluoxetine

ACTIVE COMPARATOR

Participants will be taking 20mg fluoxetine daily.

Drug: Fluoxetine

placebo

PLACEBO COMPARATOR

Participants will be taking one placebo capsule daily.

Drug: Placebo

Interventions

Fluoxetine DRUG

Participants will receive 20mg of fluoxetine daily for 7 days. Tablets encapsulated to aid blinding.

fluoxetine

Placebo DRUG

Participants will receive one dose placebo (sucrose) daily for 7 days. Tablets encapsulated to aid blinding.

placebo

Eligibility Criteria

• Age: 18 Years - 24 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Be aged 18-24 years (inclusive)
• Be resident in the UK for the duration of the study
• Have normal or corrected to normal vision
• Participant is willing and able to give informed consent for participation in the research
• Sufficiently fluent English to understand and complete the study

You may not qualify if:

• The participant may not enter the study if ANY of the following apply:
• Psychiatric History:
• Current or past diagnosis of any psychiatric disorder, as determined by the Structured Clinical Interview for the DSM-5 (SCID-5) and self-report. This includes, but is not limited to, depression, anxiety disorders, alcohol or drug dependency, personality disorders, suicidal ideation, and other psychiatric conditions;
• First degree relative with a diagnosis of mania;
• Lifestyle:
• Heavy smoker or vaper (\> 10 cigarettes per day, or \>2 mL e-liquid, or \>15mg/day from a nicotine patch);
• Heavy use of caffeine (drink \> 4 of 250ml cups/cans of coffee or energy drinks per day);
• Heavy drinker (drink \>14 standard alcoholic drinks per week);
• Current or recent use (in the last 3 months) of any psychoactive substance according to self-report and a urine drug test screening for recent use of 10 common recreational substances;
• Physical Health:
• Severely underweight or overweight in a manner that renders them unsuitable for the study in the opinion of the study medical advisor;
• Known contraindication to fluoxetine, such as hypersensitivity to fluoxetine or any component in its formulation;
• Pregnancy, as determined by a urine pregnancy test or plans to become pregnant within the next 3 months;
• Breastfeeding;
• Not able to consume gelatine;

Sponsors & Collaborators

• University of Oxford: lead
• Wellcome Trust: collaborator
• National Institute for Health Research, United Kingdom: collaborator

Study Sites (1)

Department of Psychiatry, University of Oxford

Oxford, Oxfordshire, OX3 7JX, United Kingdom

RECRUITING

MeSH Terms

Conditions

Depression

Interventions

Fluoxetine

Condition Hierarchy (Ancestors)

Behavioral Symptoms; Behavior

Intervention Hierarchy (Ancestors)

Propylamines; Amines; Organic Chemicals

Central Study Contacts

Catherine Harmer, PhD

CONTACT

+441865 618326; catherine.harmer@psych.ox.ac.uk

Ye Wo, MSc

CONTACT

+447564300004; ye.wo@psych.ox.ac.uk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor of Cognitive Neuroscience

Model Details: Participants will be assigned to receive either fluoxetine or placebo. Fluoxetine is not being administered for treatment purposes, the purpose is to understand the mechanisms underpinning its effects.

Study Record Dates

• First Submitted: December 3, 2025
• First Posted: February 20, 2026
• Study Start: October 1, 2025
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026
• Last Updated: February 20, 2026

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ANALYTIC CODE
• Time Frame: Data will be available in a few months after all data has been completed (ETA Oct 2026), unblinding has occurred (ETA Dec 2026), and all data analyses has been completed (Dec 2027).
• Access Criteria: Fully de-identified individual participant data (IPD) and relevant supporting documentation may be shared with academic researchers for scientific research purposes. Access will be limited to researchers affiliated with recognised academic or research institutions, including those outside of the UK and EU. Approved researchers will be granted access only to fully de-identified IPD and relevant supporting materials. Data will be shared via secure transfer methods or through a controlled-access data repository.

Locations

GB (1)