Linking the Meso and Macroscale Determinants of Cerebral Ageing

Neuroimaging methods provide a non-invasive means to understand how the brain changes over the course of a typical lifespan in-vivo. Macroscale neuroimaging studies of “healthy” human ageing rarely consider small-scale (microscale) biological processes that underlie age-related changes to the tissues, processes and functions of the brain. By considering these microscale changes, we stand to better understand the underlying causes and processes that give rise to age-related cerebral changes captured by these images. This review addresses the gap by describing the known and putative connections between neuroimaging studies of ageing and molecular biology. The connections are described in relation to structural, inflammatory, vascular, and metabolic brain changes with age. We summarise the cerebral changes, how they can be visualised with neuroimaging methods and the microscale biological processes that underlie the visible macroscale changes.