ABSTRACT
Ageing has been defined as a complex process of accumulation of molecular, cellular and organ damage leading to a loss of function and an increased vulnerability to disease and death.37 This is an important area because many diseases affecting the brain develop in older individuals with age as the most significant risk factor. A main issue is in trying to define attributes of normal and successful brain ageing and distinguish these from changes seen in the brains of elderly people who have early forms of neurodegenerative disease. There is great interest in identifying features that are linked to successful normal brain ageing that might be adapted to therapeutic strategies. Cross-sectional studies of the past have now given way to studies using high resolution and functional imaging in longitudinal series using the same individuals with a main aim to identify biomarkers that can reliably predict cognitive decline in the elderly.44 Epidemiology-based community cohort studies involving longitudinal cognitive assessment with neuropathological and genetic end points are also starting to be informative in relation to the significance of changes seen in the ageing brain.11 Work in experimental systems, including fly and worm models, is providing information about signalling pathways and genes that are involved in neuronal ageing and this information is being applied to human brain studies.8
