The PROMEX study
Research type
Research Study
Full title
Gut feeling: understanding the mechanisms underlying the antidepressant properties of probiotics (the PROMEX study)
IRAS ID
251923
Contact name
Viktoriya Nikolova
Contact email
Sponsor organisation
King's College London
Clinicaltrials.gov Identifier
Duration of Study in the UK
3 years, 0 months, 1 days
Research summary
Depression is a common and complex mental illness. It is estimated that up to 60% of people with depression do not respond to currently available treatments. Accumulating research has suggested that probiotics (‘good bacteria’) may reduce anxiety, stress and depression. Most recently, two placebo-controlled trials in patients with depression demonstrated that 8 weeks of daily probiotic use, in addition to an ongoing antidepressant, can significantly reduce depressive symptoms (Kazemi et al. 2018; Akkasheh et al. 2016). The mechanisms underlying these effects are not fully understood at present.
This study will aim to improve our understanding of the relationship between the gut and the brain in depression and the mechanisms underlying the role of probiotics as potential treatment by examining the gut microbiota (bacterial composition of the gut) and how it relates to neurotransmitter and inflammatory systems with known involvement in depression. Specifically, we will examine whether: 1) the gut microbiota differs between healthy individuals and those with depression; 2) the gut microbiota changes with probiotic use; 3) probiotics can influence the levels of certain brain chemicals and brain activity; 4) levels of particular bacteria relate to improvements in mood; and 5) how these effects are related to levels of inflammation in the body.
We will recruit 50 people with depression and 25 well-matched healthy volunteers and collect stool samples to analyse and compare the microbiome. We will then randomly assign the people with depression to either a probiotic or placebo for 8 weeks, while they remain on their ongoing antidepressant treatment. Participants will be asked to provide stool and blood samples and complete mood questionnaires at week 4 and week 8. A subset of 10 per group will also undergo a brain scan before and after the treatment. These data will then be analysed to address the remaining aims as outlined above.REC name
London - Surrey Research Ethics Committee
REC reference
19/LO/0761
Date of REC Opinion
3 Jun 2019
REC opinion
Further Information Favourable Opinion