Dr Katie O’Brien obtained her doctorate from King’s College London in 2017 under the supervision of Prof. Stephen Harridge. She undertook post-doctoral research investigating drug induced mitochondrial toxicity in the context of hypoxia at the University of Cambridge with Prof. Andrew Murray, and in collaboration with GlaxoSmithKline and AstraZeneca. Following this, she received a Marie Curie Global Research Fellowship between the University of Cambridge and University of California, San Diego with Dr Tatum Simonson to investigate high-altitude metabolic phenotype driven by unique Andean genetics. She completed further post-doctoral training at the University of Colorado with Prof Colleen Julian, where she investigated metabolic and vascular adaptation to high-altitude during pregnancy in highland Andeans. She re-joined King’s College London in 2025 as Lecturer in Human Physiology. 

Her research focuses upon human adaptation to hypoxic stress (impaired cellular oxygen availability), with a specific interest in the control of cellular metabolism in hypoxic environments. Through integration of cellular, tissue and systemic approaches, her work aims to further understanding of molecular mechanisms linking adaptive genetic signals to metabolic phenotype in native highland populations. This includes metabolic regulation during high-altitude pregnancy.