1 Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland; APC Microbiome Institute, University College Cork, Cork, Ireland. Electronic address: g.clarke@ucc.ie.
2 Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
3 Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland, School of Medicine, Baltimore, MD, USA.