Anxiety, Cortisol, Decision Making, Emotion, Humans, Magnetic Resonance Imaging, Prebiotics
Conditions
Brief summary
The aim is to test if dietary supplementation with prebiotics reduces measures of anxiety in healthy human participants with high self-reported levels of anxiety. Study will test for an effect on behavioural, neuroendocrine and brain imaging markers of anxiety.
Interventions
DIETARY_SUPPLEMENTPrebiotics
Galactooligosaccharides (GOS) (prebiotics) will be consumed by the participants for 4-6 weeks
DIETARY_SUPPLEMENTMaltodextrin (placebo)
Maltodextrin (placebo) will be consumed by the participants for 4-6 weeks
Sponsors
National Health and Medical Research Council, Australia
Oxford Health Biomedical Research Centre (OH BRC) support scheme
Wellcome Centre for Integrative Neuroimaging
Monash University
University of Oxford
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Masking description
Both intervention and placebo products are similar in colour, texture, and taste. A third party, independent of the daya-to-day research coordinator, will randomise treatments.
Intervention model description
Crossover Assignment Randomised Double-blind Cross-over design with 4-6 weeks of prebiotics intervention and 4-6 weeks of placebo intervention. The first intervention phase will be followed by a 3 week wash-out period prior to the second intervention phase.d.
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Trait anxiety levels \> 40 on STAI trait inventory * Participant is willing and able to give informed consent for participation in the study * Not currently taking any psychoactive medications
Exclusion criteria
* Pregnant participants * No contraindications to prebiotic administration * Antibiotic, probiotics and/or prebiotic treatment in at least the two previous months. * Participants who are taking any other food supplements that, in the opinion of the Investigators, may affect the results. * Participants who are taking any medications that, in the opinion of the Investigators, may affect the results. * Any significant change in diet which, at the discretion of the Investigators, may affect the results. * Participants who have recently participated in another research trial which, at the discretion of the Investigators, may affect the results. * A history of dementia, traumatic brain injury or stroke. * Anyone who is unable to perform the behavioural tasks. * Current use of any psychoactive medication. * Current use of psychological treatment. * Anyone who does not have adequate understanding of English, sufficient to give informed consent. * Any person who has a history of drug abuse or a previous history of a neurological, or has a history of neurosurgical procedure is excluded as they may be at increased risk of epilepsy and data collected may be influenced by their condition. * Anyone with any metal implants or implantable device would be excluded from any brain imaging studies as indicated by the MRI safety screening form.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Cortisol awakening response (CAR) | Cortisol awakening responses will be measured at the end of the first intervention phase (4-6 weeks after study entry) and at the end of the second intervention phase (11-15 weeks post study entry). | CAR, a marker of stress responsivity, should be decreased after taking prebiotics compared to placebo (as previously found in non-anxious participants in Schmidt et al., 2015, Psychopharmacology) |
| Brain imaging (BOLD fMRI activity) in amygdala and cortical regions | Brain imaging will be measured at the end of the first intervention phase (4-6 weeks after study entry) and at the end of the second intervention phase (11-15 weeks post study entry). | Brain imaging (BOLD fMRI activity) in amygdala and cortical regions Will provide neural measures of threat reactivity. We predict decreased amygdala and/or increased parietal-prefrontal brain activity after prebiotics compared to placebo, indicating an anxiolytic-like profile (fearful -neutral face trials in the low load condition) (as in Bishop et al, 2007 and Ironside et al, 2017) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Changes in gut microbiome | Changes in the microbiome will be measure using a single stool/faecal sample at four time points: baseline (0 weeks), following first intervention (4-6 weeks), following washout (7-9 weeks), and following the second intervention (11-15 weeks). | Availability of specific bacteria in microbiome will change as function of prebiotics and not during placebo. The change will be measured at the start of each intervention compared to the end of each intervention |
Countries
United Kingdom
Contacts
Primary ContactGershon Spitz, PhD
Outcome results
None listed