Morphologic changes in the mesolimbic pathway in Parkinson's disease motor subtypes

Area of Science:

• Neuroimaging
• Neurodegenerative Diseases
• Brain Anatomy

Background:

• Parkinson's disease (PD) is a neurodegenerative disorder linked to gray matter atrophy.
• Cortical atrophy patterns may differentiate PD motor subtypes.
• Subcortical volume differences between subtypes are not well-established.

Purpose of the Study:

• To investigate subcortical volumetric and shape differences in Parkinson's disease patients.
• To compare these differences between tremor-dominant (TD) and postural instability gait dominant (PIGD) subtypes.
• To explore potential correlations with clinical measures.

Main Methods:

• Structural MRI scans (3.0T) were acquired from 21 PD patients (12 TD, 9 PIGD) and 20 controls.
• Subcortical volumes were analyzed using FreeSurfer.
• Shape analysis was performed using FIRST to detect differences between groups and subtypes.

Main Results:

• No significant subcortical volume differences were found between PD motor subtypes.
• PD patients exhibited significantly increased hippocampal volume compared to controls (p=0.03).
• Significant shape differences in the right nucleus accumbens (NAcc) were found between PD patients and controls, and between subtypes, driven by the TD group.

Conclusions:

• While subcortical volumes did not differ between PD subtypes, hippocampal volume was elevated in PD patients.
• Right NAcc shape alterations in PD were primarily associated with the TD subtype.
• These findings may reflect dopaminergic therapy effects on the mesolimbic pathway; further research is warranted.