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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
80
Participants will be taking a 20mg fluoxetine capsule daily for 7 days.
Participants will be taking a placebo capsule daily for 7 days.
University of Oxford Department of Psychiatry
Oxford, United Kingdom
Behavioural measure: Facial Expression Recognition Task (FERT)
Recognition of positive (happy, surprise) faces in the Facial Expression Recognition Task.
Time frame: On the last day of the 7-day treatment
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.
Time frame: 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.
Time frame: 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.
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
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.
Time frame: 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.
Time frame: On the last day of the 7-day treatment
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