Citalopram and Self Emotional Processing

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

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.

Eligibility Criteria:
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)