Inside and outside the body space: a study on environmental knowledge, interoceptive and functional body representations in Mild Cognitive Impairment

Objectives Spatial navigation is gaining recognition as a cost-effective cognitive biomarker for identifying Alzheimer's disease (AD) in its preclinical stages [1]. Building on evidence that different types of space can be distinguished [2], and grounded in the embodied cognition framework [3], we extend current findings by comparing healthy aging individuals with those diagnosed with Mild Cognitive Impairment (MCI) and AD in their ability to process navigational space, peripersonal space, and body space - the latter being experienced both internally, through interoception, and externally, through exteroception. Materials The study includes 25 healthy controls (HC) (mean age = 65.7 ± 4.76), 22 individuals diagnosed with MCI (mean age = 70.1 ± 4.89) and 8 patients with AD (mean age = 71.1 ± 2.94). All participants completed tasks probing different interoceptive dimensions, namely, interoceptive accuracy, awareness, and sensibility, a computerized battery of action-oriented (aBR) and non–action-oriented (naBR) body representation tasks, desktop-based virtual navigational tasks assessing landmark, route, and survey knowledge, as well as standard neuropsychological assessments of cognitive functioning. Methods This was a cross-sectional comparative study. Participants underwent a series of cognitive tasks in a controlled setting, probing different kinds of space. Group differences were assessed using non-parametric statistical analyses (Mann-Whitney U test). Results Preliminary results suggest that all patients exhibit reduced interoceptive sensitivity compared to healthy controls. Furthermore, the AD group shows significantly lower performance in an interoceptive accuracy task. Both patient groups take longer to complete the aBR and naBR tasks; the AD group also show reduced accuracy in the naBR task. MCI patients are slower in completing all navigation tasks, and all patient groups perform less accurately in both landmark and route tasks. Discussion The results show an early involvement of interoceptive processing, functional body representation, and navigational abilities in the initial stages of cognitive decline. Difficulties in processing various types of bodily and extra-bodily space may thus represent an early marker of neurodegeneration. Conclusions Our findings align with the embodied cognition framework [3], reinforcing the idea that mental representations of body space and navigational space are distinct yet interconnected. This opens new directions for research on how body-related cognitive processes influence broader cognitive functions.