Exploring the relationship between interoception and mental body representation in Parkinson's disease

Interoception refers to the process through which the nervous system detects, interprets, and integrates internal bodily signals, forming a dynamic representation of the body's internal state at both conscious and unconscious levels. It is commonly conceptualized along three dimensions: interoceptive accuracy, interoceptive awareness and interoceptive sensitivity. Mental body representation (MBR) is a multifaceted cognitive construct encompassing structural, spatial, lexical, and semantic components of the body. A widely accepted taxonomy distinguishes between two types of MBR: action-oriented representations and non-action-oriented representations. To date, only a few studies have examined interoception and MBR in Parkinson's disease (PD), often yielding inconsistent findings, and no study has directly investigated the relationship between these two domains in this clinical population. This study therefore aims to (1) further characterize interoceptive and MBR profiles in PD and (2) explore their potential association. Twenty-seven patients with PD and twenty-four healthy controls completed a neuropsychological battery assessing global cognitive functioning, interoceptive abilities, MBR, and depressive and apathetic symptoms. Mann-Whitney analyses revealed significantly poorer MBR performance in patients compared with healthy controls. Spearman correlations showed significant associations between action-oriented MBR and global cognitive functioning as measured by the Parkinson's Disease Cognitive Rating Scale (PD-CRS). Regression analyses further demonstrated that PD-CRS performance significantly predicted action-oriented MBR abilities. These findings indicate a characteristic difficulty among individuals with PD in mentally representing body features. Moreover, results suggest that both cortical and subcortical cognitive functions contribute to supporting action-oriented MBR.