Background: The severity of motor symptoms in Parkinson's disease (PD) does not always correlate with the degree of nigral dopaminergic neuronal loss. Individuals with greater motor reserve may have milder motor signs than their striatal dopamine loss. In this study, we explored the functional brain network associated with motor reserve in early-stage PD. Methods: We analyzed 134 patients with de novo PD who underwent dopamine transporter scans and resting-state functional magnetic resonance imaging. We estimated individual motor reserve based on initial motor deficits and striatal dopamine depletion using a residual model. We applied network-based statistic analysis to identify the functional brain network associated with the measure of motor reserve (ie, motor reserve network). We also assessed the effect of motor reserve network connectivity strength on the longitudinal increase in levodopa-equivalent dose during the 2-year follow-up period. Results: Network-based statistic analysis identified the motor reserve network composed of the basal ganglia, inferior frontal cortex, insula, and cerebellar vermis at a primary threshold of P value 0.001. Patients with an increased degree of functional connectivity within the motor reserve network had greater motor reserve. There was a significant interaction between the motor reserve network strength and time in the linear mixed model, indicating that higher motor reserve network strength was associated with slower longitudinal increase in levodopa-equivalent dose. Conclusions: The present study revealed the functional brain network associated with motor reserve in patients with early-stage PD. Functional connections within the motor reserve network are associated with the individual's capacity to cope with PD-related pathologies.
Bibliographical noteFunding Information:
Prof. Chung and Prof. Lee were the recipients of the grant from the National Research Foundation of Korea (NRF-2018R1D1A1B07048959 and NRF-2016R1A2A2A05920131, respectively). Prof. Jeong was supported by the Korea Health Industry Development Institute (HI14C2768).
All Science Journal Classification (ASJC) codes
- Clinical Neurology