Objective: To explore the functional brain network associated with motor reserve in early-stage Parkinson’s disease (PD).

Background: The severity of motor symptoms in PD does not always correlate with the degree of nigral dopaminergic neuronal loss. Individuals with greater motor reserve, who can better cope with PD-related pathologies, may have milder motor signs than their striatal dopamine loss.

Method: We analyzed 134 patients with de novo PD who underwent dopamine transporter scans and resting-state functional MRI. We estimated individual motor reserve based on initial motor deficits and striatal dopamine depletion using a residual model. We applied network-based statistic (NBS) analysis to identify the functional brain network associated with the measure of motor reserve (i.e., motor reserve network). We also assessed the effect of motor reserve network connectivity strength on the longitudinal increase in levodopa-equivalent dose (LED) over the 2-year follow-up period.

Results: NBS 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 LED.

Conclusion: 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.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/identifying-the-functional-brain-network-of-motor-reserve-in-early-parkinsons-disease/