Separable, symptom specific alterations in brain microstructure associated with early-stage Parkinson's disease

Area of Science:

• Neuroimaging
• Neuroscience
• Neurology

Background:

• Parkinson's Disease (PD) diagnosis relies on motor symptoms, but non-motor symptoms often precede them, indicating prodromal PD.
• The neural basis and dopamine depletion effects on motor versus non-motor symptoms in PD are not fully understood.

Purpose of the Study:

• To investigate microstructural brain changes in early-stage Parkinson's Disease using correlational tractography.
• To determine the association between white matter integrity, motor symptoms, and non-motor symptoms in PD.

Main Methods:

• Applied multi-shell, diffusion-weighted magnetic resonance imaging (dMRI) to 8 early-stage PD patients and 5 healthy controls.
• Utilized correlational tractography to quantify groupwise differences in white matter integrity, with and without age correction.
• Assessed motor, cognitive, and mood functions in all participants.

Main Results:

• Correlational tractography identified distinct microstructural changes associated with PD status.
• Quantitative anisotropy (QA) from positively associated fibers correlated with cognitive function; QA from negatively associated fibers correlated with motor function.
• Age-uncorrected analyses showed QA of positively associated fibers correlated with depressive mood, indicating an age-related effect.

Conclusions:

• Motor and non-motor symptoms in early PD are associated with distinct anatomical pathways, suggesting separate pathophysiological mechanisms.
• Correlational tractography is a suitable method for evaluating structural connectivity changes in neurodegenerative diseases.
• Findings may inform future therapeutic interventions for Parkinson's Disease.