The Landscape of Brain Ageing: A Population-Based Framework for Individual Differences

Why do some individuals experience accelerated brain ageing while others do not? Answering this requires moving beyond group averages to understand the vast heterogeneity of the ageing process, both in healthy ageing and in pathology. This project will establish a framework for mapping this variability by creating individualised brain profiles from over 30,000 MRI scans. Crucially, these will be derived from diverse global cohorts including underrepresented populations to build more generalisable models of brain health. Using BrainCharts population modelling and unsupervised dimensionality reduction methods, I will create a configuration space where each person's position reflects their unique structural pattern and their trajectory reveals personalised ageing paths. By integrating multi-scale data, from biological and modifiable risk factors to molecular information, I will uncover the mechanisms driving these individual pathways. Sophisticated models (Graph Neural Networks) will integrate features to predict cognitive decline. This project will provide researchers with an important and inclusive way to understand brain ageing. It will deliver a publicly available dataset of ageing patterns and new tools to guide future experiments and clinical trials, building a systems-level view of neurodegeneration that accounts for individual differences and helps close the representation gap in neuroimaging. Keywords: brain ageing, BrainCharts, neuroimaging, dementia