Nick Fox is Professor of Neurology and MRC Senior Clinical Fellow at UCL. He has made a major contribution to the use of magnetic resonance imaging in the diagnosis of dementia and in tracking disease progression. He developed novel techniques for measuring changes using serial-registered MRI brain scans and a new method – the boundary shift integral – enabling much more precise quantitation. This allows structural cerebral changes to be measured and localises cerebral atrophy in pre-symptomatic Alzheimer’s disease. His methods have been adopted around the world. Recently, in the first large immunotherapy trial in Alzheimer’s he showed that amyloid removal leads to significant and unexpected brain volume changes.