The goal of this study is to investigate how a common antidepressant citalopram (which increases the levels of the chemical messenger serotonin), affects how a key area of the brain involved in depression (the amygdala) responds to emotional information. Healthy participants will undergo medical and psychiatric health screening, after which they will be assigned to receive either a single dose of citalopram (20mg) or placebo, and undergo brain scanning (7T fMRI) whilst viewing emotional faces. Since the scan uses high field strength, the investigators will be able to see effects of citalopram on different subfields within the amygdala which will help to understand how citalopram might be working.
Antidepressants typically decrease amygdala response to negative stimuli while enhancing response to positive stimuli, but it is unclear at a mechanistic level how increasing serotonin would have this opposing effect. One hypothesis is that although positive and negative cues activate the same area at a global level, more detailed characterisation may reveal key differences in processing in terms of localisation or response function. Until now, due to methodological restriction, the amygdala has been mostly studied as a single structure. It is however known that it consists of a number of subfields, which are likely to play distinct roles in emotional processing. In this study the investigators will make use of 7T fMRI scanning to study the effects of a single dose (20 mg) of citalopram (selective serotonin reuptake inhibitor, SSRI) on these subfields during emotional face processing, allowing greater precision to identify underlying neural mechanisms underpinning psychological effects.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
50
Participants will receive a single dose (20mg) citalopram. Tablets encapsulated to aid blinding. To take per oral once.
Participants will receive a single dose of placebo (sucrose). Tablets encapsulated to aid blinding. To take per oral once
University of Oxford, Department of Psychiatry
Oxford, Oxfordshire, United Kingdom
RECRUITINGNeural measures: fMRI BOLD univariate analysis
Blood-oxygen-level-dependent (BOLD) fMRI (region of interest (ROI) analysis amygdala) during the performance of an emotional faces task. Differential amygdala response to fearful and happy faces. Univariate analysis
Time frame: 3 hours after dosing for approximately 1 hour
Neural measures: fMRI BOLD multivariate analysis
Blood-oxygen-level-dependent (BOLD) fMRI (region of interest (ROI) analysis amygdala) during the performance of an emotional faces task. Amygdala response to fearful and happy faces. Multivariate pattern analysis.
Time frame: 3 hours after dosing for approximately 1 hour
Behavioural measures: Accuracy during gender discrimination task
Accuracy (% correct) of gender identification will be measured to ensure participant engagement throughout the task.
Time frame: 3 hours after dosing for approximately 1hour
Behavioural measures: Reaction times during gender discrimination task
Reaction times (ms) of gender identification will be measured to ensure participant engagement throughout the task.
Time frame: 3 hours after dosing for approximately 1hour
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