Professor John T O’Brien is Professor of Old Age Psychiatry in the Department of Psychiatry at the University of Cambridge and National Institute for Health Research (NIHR) National Specialty Lead for Dementia. He is an Emeritus NIHR Senior Investigator and Fellow of the UK Academy of Medical Sciences.

His research interests include the application of neuroimaging in old age psychiatry; dementia with Lewy bodies; the role of vascular factors in dementia and depression and clinical trials. He has been a member of the NICE Dementia Guideline group and is a Past President of the International College for Geriatric Psychoneuropharmacology (ICGP).