Interoceptive predictors of daily functioning in aging and their interaction with exteroceptive bodily representations.

Aging leads to progressive changes in bodily functions that affect cognition and everyday life. Older adults often experience difficulties in daily functioning due to declines in two interconnected domains: interoception, the ability to sense and regulate internal bodily states, and exteroceptive body representations. While previous studies have noted these connections, systematic investigation into how interoception and exteroceptive body representations jointly influence daily functioning remains limited. This study had two main aims: (1) to develop a battery of tests assessing interoceptive states, multisensory perception, and exteroceptive body representations; and (2) to examine whether early interoceptive changes predict functional decline, potentially interacting with multisensory perception and bodily representation processes. We tested 60 healthy adults (aged 21-87) using a multimodal battery measuring interoceptive accuracy, sensibility, and awareness, along with assessments of body image, peripersonal space, tactile acuity, and sensorimotor functions. Daily functioning was evaluated using the SF-36 Health Survey. A Partial Least Squares Regression approach identified predictors of functional outcomes. Interoceptive sensibility, particularly self-regulation and body trust, was a key predictor of limitations in physical health, emotional wellbeing, and fatigue. Mean heart rate also contributed to fatigue perception. Exteroceptive body representations, including body image and peripersonal space processing, interacted with interoception in predicting daily functioning. These findings highlight the link between internal and external body processing in aging. Identifying these predictors not only guides the refinement of the test battery but also informs the development of targeted assessments and interventions aimed at promoting autonomy and enhancing quality of life in older adults.