Multi-scale cortical morphometry reveals pronounced regional and scale-dependent variations across the lifespan

Motivation: Brains are fractal-like objects, with shape information distributed across length scales. Accurate and comprehensive descriptions of healthy ageing effects are needed to study and compare other processes such as neurological disorders. Goal(s): We utilise fractal properties and multi-scale information to give a more thorough and accurate description of morphological changes due to healthy ageing. Approach: We compute shape metrics as scale-dependent variables and infer ageing trajectories across the lifespan, contrasting scale-dependent and regional differences. Results: Different length scales highlight different aspects of ageing effects, and regional differences in ageing trajectories are more pronounced at coarser scales. Impact: Our multi-scale description of lifespan healthy ageing effects on cortical morphology reveals complementary information contained in different spatial scales and can be used as a normative model in future. Viewing morphometrics as functions of length scale reconceptualises quantitative morphometry.