Inside and outside the body space: A study on environmental knowledge, interoceptive and functional body representations in the prodromal stage of dementia

Background: There is increasing interest in identifying sensitive cognitive markers for the early detection of Alzheimer’s disease (AD). Spatial navigation has emerged as a promising marker, as impairments in both egocentric and allocentric navigation have been reported in preclinical AD and mild cognitive impairment (MCI). However, findings regarding the relative involvement of these navigational representations remain inconsistent. Moreover, little is known about how MCI affects other forms of spatial representation beyond navigation. Objective: The present study aims to investigate navigational, inner, and outer bodily representations in individuals with MCI, in order to provide a broader characterization of cognitive changes associated with this condition in different space representations. Methods: We conducted a cross-sectional comparative study involving 28 healthy controls (HC) and 25 participants diagnosed with MCI (PtwMCI). All participants completed tasks and questionnaires probing: a) different interoceptive dimensions (interoceptive accuracy [IAcc], awareness [IAw], and sensibility [ISe]); b) action-oriented (aBR) and non–action-oriented (NaBR) body representations; c) landmark, route, and survey knowledge of a virtual environment. Results: PtwMCI showed reduced IAcc and ISe, and performed less accurately in both landmark and route tasks compared to HC. Conclusions: Our findings indicate early impairments in the inner body (interoceptive) and navigational processing, even at the initial stages of cognitive decline. These difficulties may thus represent an early marker of neurodegeneration. This opens new directions for research on how body-related cognitive processes influence broader cognitive functions in the Alzheimer’s disease continuum.