Healthy
Conditions
Keywords
serotonin, interoception, ssri, anxiety
Brief summary
The goal of this crossover study was to learn about the potential regulatory role of serotonin in interoceptive processing and its relationship to levels of state anxiety. This experiment directly compared the impact of a selective serotonin reuptake inhibitor (SSRI) (20mg CITALOPRAM) to that of a PLACEBO on the neural processing of ordinary interoceptive sensations and the relationship of these influences to anxious states. Healthy young volunteers completed the visceral interoceptive attention task with each treatment condition (citalopram and placebo). The task involves focusing attention on heart, stomach, or visual sensation control while scanned with functional magnetic resonance imaging (fMRI). The difference in haemodynamic response between interoceptive sensation(s) and visual sensation (i.e. the relative interoceptive response) is compared between treatment conditions. State anxiety is measured at each test period. It is used to test for a moderating effect of state anxiety on the influence of serotonin in interoceptive processing and used post-hoc to explore associations between changes in state anxiety and changes of interoceptive relative interoceptive response due to the SSRI.
Interventions
DRUGCitalopram 20mg
Doses were delivered in gelatine capsules filled with microcrystalline cellulose.
DRUGPlacebo
Doses were gelatine capsules filled with microcrystalline cellulose
Sponsors
University of Sussex
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
\- healthy volunteer
Exclusion criteria
included: * the presence of significant ongoing medical condition; * pregnancy or breastfeeding; * currently taking any medication (excluding contraceptive pill); * first-degree family history of bipolar disorder; * an indication of current or historical mental health disorder, * MRI scanner contraindications (e.g. metallic implants) * data that is unanalyzable due to movement * excessive side effects of the drug (e.g. nausea)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| relative neural interoceptive response - heart | 15 minutes | Neural response, inferred via functional magnetic resonance imaging from focusing attention on the heart, minus the response during focus on a visual stimulus |
| relative neural interoceptive response - stomach | 15 minutes | Neural response, inferred via functional magnetic resonance imaging from focusing attention on the stomach, minus the response during focus on a visual stimulus |
| State Anxiety | 5 minutes | State Trait Anxiety Inventory |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Heartrate | Before scans of each session, 2 minutes | Participants had their heartrate recorded with the participant relaxed and sitting. |
| Metacognitive Interoceptive Insight | 45 minutes | Ability of confidence to predict accuracy when making decisions about whether heartbeat is in sync with an auditory tone. This is an exploratory measure. |
| Anatomical scan and fieldmaps | 6 minutes, at scan | For coregistration of functional magnetic resonance images |
| Cerebral Blood Flow Change | 2 minutes, at scan | Perfusion imaging, to control for effects of citalopram on blood flow |
| Physiological and Psychological state | Measured twice, for 2 minutes, before and after scanning. Average taken to estimate state inside scanner. | Three scales (from 0-100) were given to assess three somatic side effects (nausea, headache and dizziness). Five anxiety-related effects (pairs of antonyms: alert-drowsy, stimulated-sedated, restless-peaceful, irritable-good-humoured, anxious-calm) were used to confirm other anxiety measures and alert the researchers to excessive side effects. Used to confirm anxiety measure detect side effects. |
| Positive and Negative Affect Scale | Measured twice, for 2 minutes, before and after scanning. Average taken to estimate state inside scanner. | Measures affective state, confirming anxiety measure |
Countries
United Kingdom
Outcome results
None listed