Not yet recruitingNAINTERVENTIONAL

Fluoxetine and Understanding Social Experiences

The FUSE study investigates how the antidepressant fluoxetine, commonly known as Prozac, affects social decision-making in young people aged 18 to 24. While antidepressants are increasingly used by young adults, especially teenage girls, we still don't fully understand how they specifically impact areas like emotional processing, social interactions, and motivation. We're recruiting 80 healthy young people who will either receive a week of fluoxetine or a dummy pill (placebo). Neither participants nor researchers will know who gets what. By studying these effects, we hope to gain a clearer picture of how antidepressants work in young people and help doctors decide who might benefit most from this type of treatment.

At a glance

Status

Not yet recruiting

Phase

Sponsor

University of Oxford

Enrolment target

Start

01 Mar 2026

Estimated completion

22 Jul 2027

Depression in Adolescence Antidepressant Activity in Healthy Volunteers Healthy Adult Participants

What is this study about?

Adolescence is a time of big changes – socially, emotionally, and in how we think. It's also unfortunately a time when many young people start to experience depression and anxiety. Getting help early is really important to stop these problems from affecting friendships, school, and overall happiness in the long run. While talking therapies are often the first choice for milder depression in young people, the use of antidepressant medications, like Prozac (also known as fluoxetine), has become much more common, especially among girls.

Even though lots of young people are using these medications, we don't fully understand exactly how they work to help with depression in this age group. This means doctors have limited information to guide their treatment choices. The FUSE study aims to change that. We're looking closely at how Prozac influences how young, healthy adults aged 18 to 24 make decisions in four key areas that are often affected by depression: how they understand emotions (like recognising facial expressions), their social interactions (like how they react to being left out), how they process rewards, and their motivation levels.

To do this, we'll ask 80 participants to take either a low dose of fluoxetine or a dummy pill (placebo) for one week. Neither the participant nor the study team will know who is getting which. We'll use various tests, some involving looking at faces and recording heart rates, to see if fluoxetine has an effect. Our goal is to figure out which specific areas of social decision-making are influenced by these medications. This research is really important because it will help us understand Prozac better and ultimately help doctors make more informed decisions about who might benefit most from antidepressant treatment.

Key takeaways

The study explores how Prozac (fluoxetine) affects social and emotional decision-making in healthy young adults.
It aims to fill gaps in our understanding of how antidepressants work in young people aged 18-24.
Participants will take either a low dose of fluoxetine or a dummy pill for one week.
The study measures changes in emotional understanding, social interactions, reward processing, and motivation.
Results will help inform doctors on who might benefit most from antidepressant treatment.
Participation involves about 7-10 days of commitment and tests, including facial recognition and heart rate monitoring.

Who may be eligible?

To take part in this study, you need to be a healthy young person between 18 and 24 years old and live in the UK. You'll need to be able to see well (with or without glasses/contact lenses) and understand English comfortably so you can understand the study instructions and give your consent to participate.

There are some reasons why you wouldn't be able to join. For example, if you've ever been diagnosed with any mental health condition, including depression, anxiety, or addiction, or if a close family member has experienced mania, this study wouldn't be suitable for you. We also can't include people who smoke or vape a lot, drink a lot of caffeine or alcohol, or who have recently used recreational drugs. We'll check for these things with a urine test and a chat.

Your physical health is important too. You can't take part if you're pregnant, breastfeeding, planning to get pregnant soon, or if you have certain health problems like serious heart, kidney, or liver issues, or a history of seizures. You also can't be in the study if you're allergic to fluoxetine or if you can't have gelatine, as our study capsules are made from it. The study doctors will review your medical history to make sure it's safe for you to participate.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 18 and 24 years old?
Do you live in the UK?
Do you have normal vision (with or without glasses/contacts)?
Do you have good English comprehension?
Have you never been diagnosed with a mental health condition?
Are you able to consume gelatine capsules?

Answer every question to see your result.

What does participation involve?

If you decide to take part in the study, you'll be one of 80 young people. First, you'll receive either a low dose of fluoxetine (Prozac) or a placebo (a dummy pill with no active ingredients) daily for one week. Neither you nor the research team will know which one you're taking. During this week, you'll come to the study centre to complete different activities and tests that look at how you process emotions, interact socially, and make decisions. Some of these tests might involve looking at faces and we'll record your heart rate. The entire study participation, including the week of taking the assigned capsules and completing the assessments, will last for about 7-10 days in total. After the study is over, if you're interested, we can send you a brief summary of what we found.

Potential risks and benefits

A potential benefit of taking part is contributing to important research that will help us understand how antidepressants affect young people, which could lead to better treatment decisions in the future. You will also receive some payment for your time. As with any medication, even a low dose for a short period, there's a small chance of side effects from fluoxetine, although serious ones are rare. The placebo has no known side effects. You are free to withdraw from the study at any time, for any reason, without it affecting your medical care or your relationship with the study team.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

University of Oxford Department of Psychiatry
Verified postcode
Oxford, United Kingdom

Common questions

What is fluoxetine?

Fluoxetine is an antidepressant medication, commonly known by its brand name Prozac. It's usually prescribed to help with depression and anxiety.

What is a placebo?

A placebo is a pill that looks exactly like the study medication but doesn't contain any active ingredients. It's used to compare the effects of the actual drug.

Will I know if I'm taking fluoxetine or the placebo?

No, this is a 'double-blind' study, meaning neither you nor the researchers will know which you are taking until after the study is complete, to keep the results fair.

How long will I need to be involved in the study?

Your involvement will be for one week of taking capsules, plus assessments, making the total time commitment around 7-10 days.

What happens to the study results?

The findings will be published in scientific journals, presented at conferences, and summarised in a way that is easy to understand for young people. You can also request a summary.

How to find out more

Catherine Harmer

catherine.harmer@psych.ox.ac.uk +44 1865 618326 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.