The Influence of Parkinson's Disease on Depression Through Structural Equation Modeling

Objective To analyze and compare the magnitudes of nonmotor symptoms in depressed individuals with and without Parkinson’s Disease. Methods Downloaded in January 2023, symptoms and characteristics of depressed individuals with and without Parkinson’s Disease were extracted from the longitudinal study Fox Insight. The directed acyclic graph theory was used to represent causal relationships and to determine the associations between nonmotor symptoms, depression, and Parkinson’s Disease. The 2-PL and the Rasch models were used to better fit the data and identify the items consistent with the assumptions. Results Dropped interests and activities was the item that was of greatest impact and most characteristic for depressed individuals both with and without PD. Double vision was the item of least difficulty while an additional item of significant impact was Preferred to stay at home . Education attainment had little to no impact on depression severity in individuals with and without PD. Conclusions Dropped interests and activities was most severe within both populations. Relatedly, an increased average number of leisure hours was associated with greater depression severity. Overall, as an individual’s depression worsens, there is an overall upward trend in the severity of their nonmotor symptoms. We recommend additional analyses on the strength of relationships between these neurologic disorders and nonmotor symptoms.