Gerard is Professor of Neurobehavioural Science in the Department of Psychiatry and Neurobehavioural Science and a Principal Investigator. His research interests include the impact of the gut microbiome on brain and behaviour across the life span, microbial regulation of tryptophan metabolism and translational biomarkers of stress-related neuropsychiatric disorders. He was included in Clarivate Analytics Web of Science Group Highly Cited Researchers list for 6 consecutive years from 2019-2024.