Visuospatial memory in healthy elderly, AD and MCI: a review.

In the literature it is commonly reported that several spatial abilities decline with normal aging, even though such a decline is not uniform. So far, it is not yet clear which spatial components present a normal age-related decline, which ones are preserved and at what point the deficit is so severe to represent an index of mild cognitive impairment (MCI) or a symptom of potential degenerative progression as in the early-stage Alzheimer's disease (AD). In particular, AD (from early onset) is characterised by impairments in constructive abilities, visuospatial intelligence, spatial short-term memory deficits, and disorders of spatial orientation (topographical disorientation). MCI indicates a condition, generally affecting older individuals, characterized by cognitive deficits including memory and/or non memory impairments and at high risk of progression to dementia. Three MCI subgroups have been distinguished and a very high risk of developing AD is associated to the amnestic MCI subtypes. Further, recent studies have suggested that the allocentric component of spatial memory might be taken as predictor of AD from MCI. Given the frequency of visuospatial deficits in early-stage AD, evaluation of visuospatial processes is a promising approach to find predictive markers of AD. Here we report a review of the literature exploring specific visuospatial components in normal aging, MCI, and AD. In this way we could shed some light on the role of these components in the progression from MCI to AD and pave the way for future studies.