This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No. 956851.

Dr. Gerard Clarke

APC Microbiome Ireland and Department of Psychiatry and Neurobehavioural Science, University College Cork, Ireland


Dr Gerard Clarke is a Lecturer in the Department of Psychiatry and Neurobehavioural Science and a Principal Investigator in APC Microbiome Ireland. His research interests include translational biomarkers of stress-related neuropsychiatric disorders, the impact of the gut microbiome on brain and behaviour across the life span, microbial regulation of tryptophan metabolism and pharmacomicrobiomics. Target human populations of his research include those with major depression and anxiety as well as gastrointestinal disorders with high psychiatric comorbidities such as irritable bowel syndrome. With over 145 publications and a H-Index of 66, he was included in Clarivate Analytics Highly Cited Researchers list for 2019 and 2020.



The Microbiome and Stress-related Psychiatric Disorders:
A Prescription for Therapeutic Targeting of the Gut-Brain Axis

The gut microbiome plays a key role in health and disease and has emerged as a pivotal regulator of gut-brain axis signalling with important implications for psychiatry and neurogastroenterology. There is continuous bidirectional communication between the gut and the brain facilitated by neuronal, endocrine, metabolic, and immune pathways. The microbiota influences these signalling pathways via several mechanisms. Preclinical studies have delineated the influence of the gut microbiome on behaviour and at a structural and functional level in distinct brain regions. Meanwhile, clinical studies have shown compositional and functional alterations in the gut microbiota in stress-related psychiatric and gastrointestinal disorders. The effects of commonly used psychotropic medications drugs on gut microbiome composition are also becoming clearer. 

This includes important direct and indirect effects of the gut microbiome on drug metabolism, absorption and efficacy. The contribution of the gut microbiome to xenobiotic metabolism is thus an important consideration for therapeutic interventions, pharmacological drug action, and chemical biotransformations. Understanding the reciprocal nature of these drug-microbiome interactions holds the potential to improve treatment outcomes or counteract adverse drug reactionsThe future of psychopharmacology drug discovery and development pipelines will routinely need to consider this often-neglected role the host microbiome in pharmacokinetics and pharmacodynamics