Objective: To investigate differences in white matter (WM) using Diffusion Basis Spectrum Imaging (DBSI) between participants with Parkinson’s disease (PD) and controls and to examine their association with cognitive and motor deficits.

Background: A growing body of evidence suggests that neuroinflammation plays a contributory role in PD pathogenesis and progression. DBSI is an advanced diffusion-based MRI analysis method that uses a linear combination of multiple diffusion tensors to describe heterogeneous components (cellularity, extracellular water/vasogenic edema, axonal injury/loss) within a volume of tissue and has been used to measure neuroinflammation and white matter injury in humans. We hypothesized that WM markers of neuroinflammation and axonal integrity would be altered in PD and may be related to motor and cognitive deficits.

Method: All participants, PD (n=102) and controls (n=51), were non-demented individuals taking part in the Protein and Imaging Biomarkers (PIB) longitudinal study of cognitive decline in PD and each completed a multi-shell diffusion MRI scan for DBSI analysis. DBSI metrics included measures of restricted fraction (DBSI-RF), hindered fraction (DBSI-HF), and fiber fraction (DBSI-FF). Changes in these metrics were analyzed using tract based spatial statistics (TBSS) and in individual WM ROIs. Participants also completed motor assessment with the Unified Parkinson’s Disease Rating Scale Part 3 (UPDRS3) and most (PD n=90, controls n=44) completed comprehensive neuropsychological testing for assessment of cognitive function. For each participant, a composite cognitive Z-score was computed across the individual cognitive domains as a measure of global cognitive severity. Statistical analyses adjusted for age, sex and education.

Results: PD participants had significantly lower WM DBSI-RF than control participants. In PD participants, WM DBSI-HF significantly correlated with increasing UPDRS3, a measure of motor severity. There was a corresponding negative correlation between WM DBSI-RF and WM DBSI-FF with UPDRS3. In PD participants, WM DBSI-FF correlated with global cognitive Z-score, a measure of cognitive severity.

Conclusion: WM integrity is altered in PD and may reflect pathological processes, including neuroinflammation and axonal injury/loss that differentially relate motor and cognitive function.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/quantification-of-neuroinflammation-and-white-matter-injury-in-parkinson-disease-using-diffusion-basis-spectrum-imaging/