Multidimensional Phenotyping and Predictive Neuropsychological Modeling of Socio-Cognitive Endophenotypes in Early Parkinson's Disease.

Background/Objectives: Socio-cognitive disorders constitute the early-stage disabling dimension of non-motor symptoms of Parkinson's disease (PD) and affect social functioning and interpersonal adjustment. However, current assessment tools do not adequately reveal the nature of these disorders. The Edinburgh Social Cognition Test (ESCoT) has recently been validated as a multifaceted, sensitive instrument for detecting this dysfunction in various neurological disorders. This study aimed to systematically examine socio-cognitive changes in early-stage PD using the ESCoT and their relationship with executive functions. Methods: This prospective case-control study included 27 early-stage idiopathic PD patients without cognitive impairment and 46 healthy controls. Social cognitive abilities were assessed using the ESCoT, and executive functions via the Frontal Assessment Battery (FAB). Group differences and inter-variable linear associations were evaluated using parametric inferential statistics. The independent predictive contribution of FAB to ESCoT performance was modeled through multiple linear regression. Results: Groups did not differ in age, sex, or education (p > 0.05). PD patients had significantly lower ESCoT total scores (45.67 ± 0.85 vs. 55.52 ± 0.63) and reduced performance across all subscales: Cognitive Theory of Mind (ToM), affective ToM, interpersonal, and intrapersonal norms (p < 0.001). In the PD cohort, FAB correlated strongly with ESCoT (r > 0.40, p < 0.05) and significantly predicted ESCoT total (R2 = 0.247, p = 0.008), affective ToM (β = 0.221, p = 0.034), and interpersonal norms (β = 0.447, p = 0.019). Conclusions: This study demonstrates, for the first time, that ESCoT can sensitively capture multidimensional social cognitive deficits in PD, even in preserved global cognitive function. The observed link with executive dysfunction underlines the need for a more integrative approach to cognitive symptoms in PD.