Objective: This study compared gray matter volume (GMV) and functional connectivity among patients with Parkinson’s disease involving postural instability/gait difficulty (PD-PIGD), patients with tremor-dominant Parkinson’s disease (PD-TD) and healthy controls.

Background: Parkinson’s disease (PD) is an age-related neurodegenerative disease. involving highly heterogeneous clinical manifestations, with the most typical motor symptoms being slow movement, tremor, stiffness, and gait/postural disturbance. The disease has been divided, based on motor symptoms, into PD involving postural instability/gait difficulty (PD-PIGD), tremor-dominant PD (PD-TD) and PD of mixed subtypes. PD-PIGD patients usually exhibit less autonomy and are more likely to fall than PD-TD patients, and they also tend to suffer more severe non-motor symptoms, faster cognitive and motor function progression, and worse response to levodopa or deep brain stimulation. Here we extensively compared GMV and functional connectivity in the brains of PD-PIGD patients, PD-TD patients and healthy controls in order to clarify the neuroanatomical and functional differences between the PD subtypes.

Method: Voxel-based morphometry of T1-weighted was used to compare GMV among 64 PD-PIGD patients, 44 PD-TD patients, and 32 controls. Then functional connectivity in regions showing reduced GMV was compared among the groups. We explored whether differences among the groups were associated with clinical characteristics and neuroimaging biomarkers using partial correlation and binary logistic regression.

Results: Our study uncovered several neuroimaging features that may help differentiate between PD-PIGD and PD-TD: not only smaller GMV of the left middle temporal gyrus but also reduced functional connectivity between that brain region and right caudate were independent risk factors for PD-PIGD.

Conclusion: PD-PIGD may be associated with more extensive cortical atrophy than PD-TD. Abnormal posture and gait in PD may involve impaired activity of the basal ganglia, cerebellum and associated fibers. Tremors may occur first in the basal ganglia, then activate the cerebello-thalamo-cortical circuit.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/differences-in-gray-matter-atrophy-and-functional-connectivity-between-motor-subtypes-of-parkinsons-disease/