Egocentric and allocentric spatial reference frames in aging: A systematic review
INTRODUCTION Mild cognitive impairment (MCI) is considered an early stage of cognitive impairment. Therefore, it is important to identify early cognitive markers of MCI conversion to dementia and topographical disorientation (TD) may help differentiate normal aging from MCI and prodromal Alzheimer's disease (AD). Our aim was to propose a new instrument in elderly healthy subjects and MCI patients of amnestic (aMCI) and non-amnestic (naMCI) type. METHOD We observed 18 healthy subjects and 18 MCI patients (9 aMCI and 9 naMCI). All participants were submitted to a neuropsychological battery and to a new experimental small-scale spatial navigation test reproducing an ideal city. RESULTS a-MCI patients performed worse in learning a new route, in replacing landmarks in the city and in drawing a map of the city. Na-MCI patients' performance was not different from that observed in healthy subjects, except for a longer time span in Route Forward learning. MCI and healthy samples showed different correlations between experimental subtests and neuropsychological tests. CONCLUSIONS Our task seems to be sensitive in pointing out differences in spatial abilities of MCI subtypes, especially with regard to the following subtests: learning a new route, retrieving a landmark's place and building a map of the environment. In comparison with more complex tests, these results allow us to consider the new tool as useful to evaluate spatial navigation in healthy elderly subjects and MCI patients.