Relationship between Motor Symptoms, Cognition, and Demographic Characteristics in Treated Mild/Moderate Parkinson's Disease

Abstract

Background: Although Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized primarily by motor symptoms, PD patients, at all stages of the disease, can experience cognitive dysfunction. However, the relationships between cognitive and motor symptoms and specific demographic characteristics are not well defined, particularly for patients who have progressed to requiring dopaminergic medication.

Objective: To examine relationships between motor and cognitive symptoms and various demographic factors in mild to moderate, PD patients requiring anti-PD medication.

Methods: Cognitive function was assessed in 94 subjects with a variety of neuropsychological tests during baseline evaluations as part of an experimental treatment study. Data were analyzed in relation to Unified Parkinson's Disease Rating Scale motor scores and demographic variables.

Results: Of the UPDRS subscores analyzed, posture/balance/gait was associated with the highest number of adverse cognitive outcomes followed by speech/facial expression, bradykinesia, and rigidity. No associations were detected between any of the cognitive performance measures and tremor. Motor functioning assessed in the "off" condition correlated primarily with disease duration; neuropsychological performance in general was primarily related to age.

Conclusion: In PD patients who have advanced to requiring anti-PD therapies, there are salient associations between axial signs and cognitive performance and in particular, with different aspects of visuospatial function suggesting involvement of similar circuits in these functions. Associations between executive functions and bradykinesia also suggest involvement similar circuits in these functions.

Fig 1. Heat map showing the relationships between cognitive test performance (based on correlation coefficients) and subscores from the Unified Parkinson’s Disease Rating Scale (UPDRS) motor scales.

Green denotes a significant negative correlation, red denotes a significant positive correlation and black denotes no significant correlation. The intensity of the color reflects the strength of the correlation.