Depression in AdolescenceFUSENCT07456501
Fluoxetine and Understanding Social Experiences
A study testing Fluoxetine in people with Depression in Adolescence and Antidepressant Activity in Healthy Volunteers, run by University of Oxford at 1 site in United Kingdom.
Trial summary
Adolescence is a critical developmental period marked by significant social, cognitive, and emotional changes. Unfortunately, it is also a time when the risk of depression and anxiety rises dramatically. Read more about this study
- Who is it for?
- Ages 18 to 24 yearsHealthy volunteers can take part
- Conditions the study is for
- Depression in Adolescence, Antidepressant Activity in Healthy Volunteers, Healthy Adult Participants
- What is being tested?
- Fluoxetine
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 80 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- Mar 2026to 22 Jul 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 24 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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
Who cannot join
- Psychiatric History:
- Current or past diagnosis of any psychiatric disorder, as determined by the 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);
Show all 23Show fewer
- Heavy alcohol 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.
- Unable or unwilling to consume gelatine (study capsules will be gelatine-based).
- 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.
- Medical History:
- Past or ongoing health issue which, in the opinion of the study medical advisor, may interfere with the safety of the participant or the scientific integrity of the study. This can include but is not limited to: seizures or epilepsy, abnormal heart rhythm, renal disease, hepatic disease, glaucoma, diabetes, bleeding disorders or clotting conditions (e.g., haemophilia, thrombocytopenia);
- Diagnosis of a significant neurological condition (e.g., epilepsy, multiple sclerosis, traumatic brain injury);
- Current or recent use of medication that might interfere or interact with the effects of fluoxetine, in the opinion of the study medical advisor. This can include but is not limited to: monoamine oxidase inhibitors (MAOIs), medications affecting serotonin levels (e.g., tramadol, triptans, St. John's Wort), anticoagulants or blood thinners (e.g., warfarin), anti-inflammatory medications (e.g., aspirin, ibuprofen), or medications known to affect heart rhythm.
- Prior Study Participation:
- Participation in any other psychological or medical experiment involving taking any kind of drug/medication/vaccine, within the last 3 months;
- Participation in any other study involving the current or similar tasks, within the last 6 months.
- Other considerations:
- •Any other significant finding which may arise during the screening process and which, in the opinion of the Principal Investigator/medical advisor, may influence the scientific integrity of the study, or the participant's safety or ability to participate in the study.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United Kingdom1 site
University of Oxford Department of Psychiatry
Oxford, OX3 7JX
Andreea Raslescu, +44 1865 618245, andreea.raslescu@psych.ox.ac.uk
Catherine Harmer, DPhil, MA, DipLATHE
About this study
Official title: Investigating the Effects of Fluoxetine on Reinforcement Learning and Social Cognition in Healthy Young People
Adolescence is a critical developmental period marked by significant social, cognitive, and emotional changes. Unfortunately, it is also a time when the risk of depression and anxiety rises dramatically. Early, effective treatment is essential to mitigate long-term impacts on relationships, education, and life satisfaction. While psychological therapies are recommended as first-line treatment for mild to moderate depression in young people, antidepressant use (particularly SSRIs such as Prozac) has risen sharply, especially among girls aged 15-17.
Despite their widespread use, there is limited research on how SSRIs address adolescent depression, leaving clinicians with little evidence to guide treatment decisions. The Fluoxetine and Understanding Social Experiences (FUSE) study aims to shed light on how Prozac (medically known as fluoxetine) influences decision-making in healthy young people in four key areas that are known to be affected by depression: emotional processing (e.g., facial expression recognition), social function (e.g., sensitivity to peer rejection), reward processing (e.g., how people learn from rewards and punishments), and motivation (e.g., how people make decisions about whether a certain outcome or reward is worth the effort to obtain). Some of the tests employed in the study use facial expression and heart-rate recording as aditional measures. We are aiming to recruit and test 80 young people between the ages of 18 and 24.
Read more
When included in the study, participants are randomly assigned to receive either a weeklong treatment with fluoxetine, or a placebo (a pill with no active ingredients). The study follows a double-blind design, which means that neither the researchers nor the participants are aware of the treatment received so as to not influence the results.
We belive that fluoxetine will have beneficial effects on social decision-making in young people, which might manifest as increased accuracy labelling positive facial expressions, less sensitivity to negative feedback, lower self-reported negative mood in response to social exclusion and reduced heart rate/negative facial expressivity in response to unpleasant social experiences.
The FUSE study aims to deepen our understanding of how antidepressants affect decision-making in young people, at a time when antidepressant prescriptions have risen but research is scarce. By identifying the exact domains of functioning which are affected by antidepressant use in this age group, this research will help inform which young people are likely to benefit most from drug treatment.
The project results will be published in peer-reviewed journals and presented at academic conferences. We are also working with a group of young advisors who will help us decide how to best share our results with others in their age group. A brief summary of the study findings will also be provided to participants who would like to receive it. All research data, excluding information that could identify participants, will be stored safely for at least 10 years after final publication or public release.
- Conditions
- Depression in Adolescence, Antidepressant Activity in Healthy Volunteers, Healthy Adult Participants
- Being tested
- Fluoxetine, Placebo
- Keywords
- Depression, Adolescent depression, Fluoxetine, Prozac, Young people, Reward processing, Effort-based decision-making, Social cognition, Peer rejection
- Medical subject headings
- Depression
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
FluoxetineDrug
Participants will be taking a 20mg fluoxetine capsule daily for 7 days.
PlaceboDrug
Participants will be taking a placebo capsule daily for 7 days.
| Study group | Role | What they receive |
|---|---|---|
| Fluoxetine | Experimental | Not described Receives: Drug: Fluoxetine |
| Placebo | Placebo comparator | Not described Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Behavioural measure: Facial Expression Recognition Task (FERT)
Recognition of positive (happy, surprise) faces in the Facial Expression Recognition Task.
Measured: On the last day of the 7-day treatment
Secondary outcomes (5)
Self-report measure: the Need Threat Scale
Participant scores on the 20-item Need Threat Scale, administered after the Cyberball task (an ostracism paradism). The scale ssesses self-reported current satisfaction levels with belonging, self-esteem, meaningful existence, and control on 7-point scales ranging from 1 (do not agree) to 7 (agree), serving as a proxy of whether these needs are threatened.
Measured: On the last day of the 7-day treatment
Behavioural measure: Probabilistic Reversal Learning Task
Performance on a probabilistic reversal learning task, in which participants learn probabilistic reward contingencies associated with three stimulus images, and them must relearn when those contingencies are reversed.
Measured: On the last day of the 7-day treatment
Behavioural measure: Piggybank Task
Performance on a task measuring action vigour, where participants have to earn monetary rewards by pressing keys to "shake" coins from virtual piggy banks. Piggybanks vary in effort and reward, requiring ongoing adjustment.
Measured: On the last day of the 7-day treatment
Self-report measure: Perception of social rejection on the Verbal Interaction Social Threat (VIST) Task
In the Verbal Interaction Social Threat Task, participants are led to believe they will be engaging in an online interaction with two other study participants. Participants are shown a series of prompts and, for each one, choose one of four possible "icebreaker" sentences (for example, under the theme of sport: "I play a team sport such as football, rugby or netball" or "I play an individual sport like tennis or athletics"). After each choice, they receive responses that appear to be typed in real time by the two peers. In reality, these responses are pre-programmed and skewed toward negative feedback for most prompts (e.g., a peer might reply "I think team sports are more like a game than a real sport"). Following each exchange, participants rate how positively or negatively they perceived the interaction.
Measured: On the last day of the 7-day treatment
Behavioural measure: Proportion of anger-related solutions found on the Word Completion Task
In this task, participants complete word puzzles with multiple solutions, many allowing aggression-related words (e.g., k n _ _ _ as "knees" or "knife"). It follows the VIST rejection paradigm, which is expected to reduce social cohesion and increase anti-social thought.
Measured: On the last day of the 7-day treatment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Mar 2026
- Study startMar 2026 (estimated)
- Primary completion20 Jul 2027 (estimated)
- Study completion22 Jul 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Depression in AdolescenceStudies of the same condition, open and under way.
- More trials run by University of OxfordThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 80 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Oxford
- Sponsor type
- University, hospital or other
- Collaborators
- Wellcome Trust, National Institute for Health Research, United Kingdom
- Responsible party
- Principal investigator, Catherine Harmer, University of Oxford
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07456501
- Sponsor's protocol ID
- MS IDREC 2337721
- Acronym
- FUSE
- Status last verified
- Mar 2026
- First submitted
- 2 Mar 2026
- Last updated
- 6 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Data which has been fully de-identified and relevant supporting materials (e.g., study protocol, data dictionary, and analysis documentation) may be shared with other academic organisations in the future, including those outside of the UK and the EU. Participants will be informed of this and specific consent for this will be obtained.
Publications
Murphy SE, Capitao LP, Giles SLC, Cowen PJ, Stringaris A, Harmer CJ. The knowns and unknowns of SSRI treatment in young people with depression and anxiety: efficacy, predictors, and mechanisms of action. Lancet Psychiatry. 2021 Sep;8(9):824-835. doi: 10.1016/S2215-0366(21)00154-1.
PubMed 34419187
Study at a glance
From the registry record, last updated by the sponsor on 6 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Investigating the Effects of Fluoxetine on Reinforcement Learning and Social Cognition in Healthy Young People
- ClinicalTrials.gov ID
- NCT07456501
- Acronym / sponsor ID
- FUSE / MS IDREC 2337721
- Conditions
- Depression in Adolescence, Antidepressant Activity in Healthy Volunteers, Healthy Adult Participants
- Keywords
- Depression, Adolescent depression, Fluoxetine, Prozac, Young people, Reward processing, Effort-based decision-making, Social cognition
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 80 participants (estimated)
- Lead sponsor
- University of OxfordUniversity, hospital or other
- Collaborators
- Wellcome Trust, National Institute for Health Research, United Kingdom
- Study start
- Mar 2026 (estimated)
- Primary completion
- 20 Jul 2027 (estimated)
- Study completion
- 22 Jul 2027 (estimated)
- First posted
- 6 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Adolescence is a critical developmental period marked by significant social, cognitive, and emotional changes. Unfortunately, it is also a time when the risk of depression and anxiety rises dramatically. Early, effective treatment is essential to mitigate long-term impacts on relationships, education, and life satisfaction. While psychological therapies are recommended as first-line treatment for mild to moderate depression in young people, antidepressant use (particularly SSRIs such as Prozac) has risen sharply, especially among girls aged 15-17.
Despite their widespread use, there is limited research on how SSRIs address adolescent depression, leaving clinicians with little evidence to guide treatment decisions. The Fluoxetine and Understanding Social Experiences (FUSE) study aims to shed light on how Prozac (medically known as fluoxetine) influences decision-making in healthy young people in four key areas that are known to be affected by depression: emotional processing (e.g., facial expression recognition), social function (e.g., sensitivity to peer rejection), reward processing (e.g., how people learn from rewards and punishments), and motivation (e.g., how people make decisions about whether a certain outcome or reward is worth the effort to obtain). Some of the tests employed in the study use facial expression and heart-rate recording as aditional measures. We are aiming to recruit and test 80 young people between the ages of 18 and 24.
When included in the study, participants are randomly assigned to receive either a weeklong treatment with fluoxetine, or a placebo (a pill with no active ingredients). The study follows a double-blind design, which means that neither the researchers nor the participants are aware of the treatment received so as to not influence the results.
We belive that fluoxetine will have beneficial effects on social decision-making in young people, which might manifest as increased accuracy labelling positive facial expressions, less sensitivity to negative feedback, lower self-reported negative mood in response to social exclusion and reduced heart rate/negative facial expressivity in response to unpleasant social experiences.
The FUSE study aims to deepen our understanding of how antidepressants affect decision-making in young people, at a time when antidepressant prescriptions have risen but research is scarce. By identifying the exact domains of functioning which are affected by antidepressant use in this age group, this research will help inform which young people are likely to benefit most from drug treatment.
The project results will be published in peer-reviewed journals and presented at academic conferences. We are also working with a group of young advisors who will help us decide how to best share our results with others in their age group. A brief summary of the study findings will also be provided to participants who would like to receive it. All research data, excluding information that could identify participants, will be stored safely for at least 10 years after final publication or public release.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Fluoxetine | Experimental | Drug: Fluoxetine |
| Placebo | Placebo comparator | Drug: Placebo |
Who may qualify
- Ages
- 18 to 24 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- 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
Key exclusion criteria (23 listed)
- Current or past diagnosis of any psychiatric disorder, as determined by the 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.
- 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 alcohol drinker (drink >14 standard alcoholic drinks per week);
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| FluoxetineParticipants will be taking a 20mg fluoxetine capsule daily for 7 days. | Drug | Fluoxetine |
| PlaceboParticipants will be taking a placebo capsule daily for 7 days. | Drug | Placebo |
Primary outcome
Behavioural measure: Facial Expression Recognition Task (FERT)
Time frame: On the last day of the 7-day treatment
Recognition of positive (happy, surprise) faces in the Facial Expression Recognition Task.
5 secondary outcomes
Self-report measure: the Need Threat Scale
Time frame: On the last day of the 7-day treatment
Behavioural measure: Probabilistic Reversal Learning Task
Time frame: On the last day of the 7-day treatment
Behavioural measure: Piggybank Task
Time frame: On the last day of the 7-day treatment
Self-report measure: Perception of social rejection on the Verbal Interaction Social Threat (VIST) Task
Time frame: On the last day of the 7-day treatment
Behavioural measure: Proportion of anger-related solutions found on the Word Completion Task
Time frame: On the last day of the 7-day treatment
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Mar 2026.
- Background: PubMed 34419187Murphy SE, Capitao LP, Giles SLC, Cowen PJ, Stringaris A, Harmer CJ. The knowns and unknowns of SSRI treatment in young people with depression and anxiety: efficacy, predictors, and mechanisms of action. Lancet Psychiatry. 2021 Sep;8(9):824-835. doi: 10.1016/S2215-0366(21)00154-1.
- Individual participant dataSharing planned: Yes. Data which has been fully de-identified and relevant supporting materials (e.g., study protocol, data dictionary, and analysis documentation) may be shared with other academic organisations in the future, including those outside of the UK and the EU. Participants will be informed of this and specific consent for this will be obtained.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Fluoxetine in people with Depression in Adolescence and Antidepressant Activity in Healthy Volunteers, run by University of Oxford at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 23 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 6 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Catherine Harmer (+44 1865 618326, catherine.harmer@psych.ox.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Behavioural measure: Facial Expression Recognition Task (FERT) (time frame: On the last day of the 7-day treatment). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07456501, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Mar 2026.