Differential changes of Social Cognition According to cognitive State and Evolution in Parkinson’s Disease

ObjectivesSocial Cognition (SC) can be impaired in Parkinson's Disease (PD), yet its longitudinal evolution relative to cognitive status is unclear. This study examined whether SC deficits in PD patients suffers different changes based on baseline cognitive status and cognitive progression.MethodsIn this observational study 48 non-demented PD patients (32 with normal cognition [PD-CN], 16 with mild cognitive impairment [PD-MCI]), and 22 healthy controls (HC) were assessed at baseline and after three years. SC was assessed for facial emotion recognition (FER), affective and cognitive Theory of Mind (ToM), and social behavior. A comprehensive neuropsychological battery provided domain-specific z-scores. Cognitive classification followed MDS Level II criteria. Adjusted linear mixed models examined SC changes. Delta scores for SC tasks and z-score changes were correlated.ResultsAt baseline, PD-MCI patients scored lower on cognitive ToM than PD-CN and HC, with no significant group differences in affective ToM, FER, or social behavior. Over three years, PD-MCI patients experienced a significant decline in cognitive ToM compared to PD-CN and HC, while affective ToM and emotion recognition declined only relative to HC. The converters (n = 16) to a worse cognitive state (PD-CN to PD-MCI or PD-MCI to PDD) showed lower baseline cognitive ToM and steeper decline than stable patients. All SC changes correlated with visuospatial ability; affective ToM also correlated with memory, language and attention, and FER with memory and executive function.ConclusionsCognitive ToM declines in parallel with cognitive deterioration in PD, while remaining stable in PD-CN. SC measures may help identify patients at higher risk of cognitive decline.