The role of egocentric and allocentric abilities in Alzheimer's disease: A systematic review

• Our results highlighted that spatial deficits appear in the earliest stages of the disease.
• There is a need for a more ecologic evaluation of the spatial functions.
• Our analysis suggested that a prevalence of allocentric impairment exists.
• A more specific deficit is found in the translation between different spatial reference frames.

A great effort has been made to identify crucial cognitive markers that can be used to characterize the cognitive profile of Alzheimer's disease (AD). Because topographical disorientation is one of the earliest clinical manifestation of AD, an increasing number of studies have investigated the spatial deficits in this clinical population. In this systematic review, we specifically focused on experimental studies investigating allocentric and egocentric deficits to understand which spatial cognitive processes are differentially impaired in the different stages of the disease. First, our results highlighted that spatial deficits appear in the earliest stages of the disease. Second, a need for a more ecological assessment of spatial functions will be presented. Third, our analysis suggested that a prevalence of allocentric impairment exists. Specifically, two selected studies underlined that a more specific impairment is found in the translation between the egocentric and allocentric representations. In this perspective, the implications for future research and neurorehabilitative interventions will be discussed.