Faecal microbiota transplantation alleviates symptoms of depression in individuals with irritable bowel syndrome: A case series

Abstract Depression is a common mental health disorder that affects more than 260 million individuals worldwide. The aetiology of depression is likely multifactorial with biological, psychological and environmental factors. Subsequently, depression can present as a number of different subtypes with varying chronicity and severity. Recently, the gut microbiome has been implicated in many gastrointestinal and extra-gastrointestinal conditions including depression. Neurological systemic effects on host biology via the gut microbiome can occur through the bidirectional link known as the gut-brain axis. Dysbiosis is the imbalance of gut flora which may instigate a dysregulated immune response and lead to disorders such as irritable bowel syndrome. In this case series, depression and irritable bowel syndrome may have a shared pathogenesis. Our study aimed to explore the effects of faecal microbiota transplantation, a procedure in which a healthy donor’s microbiota is transplanted into an unwell recipient, in three cases of concomitant depression and irritable bowel syndrome. A single centre, retrospective medical records review assessed demographics, diagnosis, medications, symptoms and medical history of the cases to determine the outcome of a faecal microbiota transplantation. Despite varying symptom onsets, types and levels of neurological and gastrointestinal symptoms there was an objective improvement in mood, medication and/or symptoms reported by the patient and/or attending physician. These results demonstrate a modest improvement in both depression and irritable bowel syndrome which would benefit from further investigation by randomised controlled trials. Faecal microbiota transplantation may be a potential adjunct therapy for treating depression and irritable bowel syndrome through the gut-brain axis.