Antidepressive Agents, Cognition, Depression, Depressive Disorder, Mental Disorder, Molecular Mechanisms of Pharmacological Action
Conditions
Keywords
Citalopram, Emotional Processing, Antidepressants, Self Processing, Healthy Volunteers
Brief summary
This study is investigating the effect of an acute dose of citalopram on emotional processing about the self. Using a parallel-group double-blind design, participants will be randomised to receive either an acute dose of citalopram or placebo. Participants will then complete a number of widely used computer-based cognitive tasks measuring emotional processing biases towards the self. This study has also been registered on OSF: https://osf.io/nhjvs/?view\_only=b39c49bddfd543b99b627dc992e49b45
Detailed description
Antidepressants are thought to operate by changing the way patients process emotional information. After a single dose of citalopram or fluoxetine healthy volunteers have been found to display an increased recognition of happy facial expressions and a reduced recognition of sad faces, in the absence of changes in mood. Studies using depressed participants have produced similar results. However, there has been comparatively little research on changes in emotional processing biases about the self following antidepressant administration. Sense of self has been proposed as fundamental for mental health, with self-schemas acting as a focus through which valence and reward influenced perception, memory and decision-making. Antidepressants may increase learning of positive information about the self, potentially remediating negative self-schema and subsequently reducing depression symptoms. In this study, the investigators aim to examine whether acute administration of citalopram is associated with an increase in positive emotional learning biases about the self. Using a parallel-group double-blind design, participants will be randomised to receive either an acute dose of citalopram or placebo. Participants will then complete a number of widely used computer-based cognitive tasks measuring emotional processing biases. Identifying early changes in cognition and behaviour following antidepressant treatment will increase our knowledge of how antidepressants operate, and provide putative targets to identify early response to antidepressants. This study has also been registered on OSF: https://osf.io/nhjvs/?view\_only=b39c49bddfd543b99b627dc992e49b45 Starting from the 8th November 2019 an additional task (the Oxford Cognition Stress Task (OCST)) was included in the test battery. This task has been developed by the Psychopharmacology and Emotion Research Laboratory (PERL), Department of Psychiatry, University of Oxford. This is an acute psychosocial stress induction paradigm, comprised of computerised cognitive tasks with an induced failure component. An algorithm varies task timing/difficulty to be just beyond participants' ability, accompanied by aversive feedback. The OCST induces mild, transient increases in stress and arousal, as indexed by heart rate, skin conductance, salivary cortisol and self-reported subjective state measures. Data for this task will be collected, analysed and published by PERL and will not be included in any publications relating to the previous registration for this study. The OCST task has been included at the end of the test battery and is therefore not expected to influence data relating to any self-report measures or tasks outlined in the previous registration This section of the study has been registered separately on ClinicalTrials.gov (titled 'Citalopram and Stress Reactivity') to reflect the separate research questions and study team involvement.
Interventions
DRUGCitalopram
Single dose administration of citalopram (20mg)
DRUGPlacebo oral tablet
Single dose administration lactose placebo tablet
Sponsors
University of Bath
University of Oxford
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Intervention model description
Following the screening, eligible participants will be randomised to receive either a single 20mg oral dose of citalopram or a matched lactose placebo tablet using an online randomisation tool. Note that the study is not assessing the safety or efficacy of citalopram, but rather using it as a probe to understand the role of serotonin in self-referential emotional processing biases.
Eligibility
Sex/Gender
ALL
Age
18 Years to 45 Years
Healthy volunteers
Yes
Inclusion criteria
* Male or Female * Aged 18 -45 years * Fluent in written and spoken English at a sufficient level to understand and complete the tasks * Body Mass Index (BMI) 18-30 * Participant is willing and able to give informed consent for participation in the study * Not currently taking any regular medications (expect the contraceptive pill)
Exclusion criteria
* Any past or current Axis 1 DSM-V psychiatric disorder * Current use of psychoactive medication (except the contraceptive pill, the Depo-Provera injection or the progesterone implant) * Current or past history of drug or alcohol dependency * History of current significant neurological condition (e.g. epilepsy) * Known hypersensitivity to the study drug * Currently pregnant or breast feeding * Previous participation in a study that uses the same or similar computer tasks as those used in the present study * Previous participation in a study that involves the use of a medication within the last three months * Significant medical condition * Smokers consuming \> 5 cigarettes per day * Individuals consuming \> 6 caffeinated drinks per day * Lactose Intolerance (due to the study involving administration of a lactose placebo tablet)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Social Evaluation Learning Task: Bias Scores | Day 1: 3-5.5 hours post drug administration | An overall index of positive or negative bias will be calculated for each referential condition (self, friend, stranger) using errors to criterion (the number of errors made before 8 rule-congruent responses). Bias is calculated by subtracting errors to criterion made when learning the dislike rule from errors to criterion made when learning the like rule. A positive value indicates a negative bias, as fewer errors are made learning the dislike rule compared to the like rule. Conversely, a negative value indicates a positive bias, as fewer errors are made learning the like rule compared to the dislike rule. The minimum possible value is - 24 (complete bias towards being liked), and the maximum value is + 24 (complete bias towards being disliked). |
| Associative Learning Task: Reaction Times (ms) | Day 1: 3-5.5 hours post drug administration | Mean reaction times will be calculated for each referential condition (self, friend, stranger), reward condition (high, medium, low) and valence condition (positive, neutral, negative) for each respective task. |
| Associative Learning Task: Accuracy (% correct) | Day 1: 3-5.5 hours post drug administration | Mean accuracy will be calculated for each referential condition (self, friend, stranger), reward condition (high, medium, low) and valence condition (positive, neutral, negative) for each respective task. |
| Self-Esteem Go/No-Go Association Task: d' | Day 1: 3-5.5 hours post drug administration | Discriminative accuracy (d') will be calculated through applying Z-score transformations, and subtracting hit z-scores from false alarm z-scores. Z-scores are adjusted by adding or subtracting .005 if hit or false-alarm rates are 0 or 1. d' -values can then be compared for each possible categorical combination to examine implicit self-biases. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Prisoner's Dilemma: Cooperative Behaviours (%) | Day 1: 3-5.5 hours post drug administration | The main outcome for this task is the proportion of rounds on which participants choose to cooperate. The conditional probability of cooperating will be calculated according to the proportion of rounds on which participants cooperated following each of the four possible outcomes. |
| Emotional Categorisation and Recall: False Alarms | Day 1: 3-5.5 hours post drug administration | Mean alse intrusions will be collected for each referential condition and valence. |
| Prisoner's Dilemma: Reaction Times (ms) | Day 1: 3-5.5 hours post drug administration | Reaction times for cooperation versus non-cooperation choices will be calculated. |
| Emotional Categorisation and Recall: Number of words categorised | Day 1: 3-5.5 hours post drug administration | The mean number of positive and negative words categorised as describing or not describing the participant/the other will be recorded. |
| Emotional Categorisation and Recall: Hits | Day 1: 3-5.5 hours post drug administration | Mean hits will be collected for each referential condition and valence. |
Countries
United Kingdom
Contacts
Primary ContactCatherine Hobbs, MSc
Backup ContactSusannah Murphy, DPhil
Outcome results
None listed