White matter microstructural characteristics in newly diagnosed Parkinson’s disease: An unbiased whole-brain study

Abstract

Parkinson’s disease (PD) is a debilitating neurodegenerative disorder. Findings on specific white matter (WM) alterations in PD have been inconsistent. We hypothesized that WM changes occur in early PD patients and unbiased whole-brain analysis may provide additional evidence of pathological WM changes in PD. In this study, we examined various indexes of WM microstructure in newly diagnosed PD patients at the whole-brain level. 64 PDs with Hoehn & Yahr stage 1 (HY1PDs), 87 PDs with Hoehn & Yahr stage 2 (HYPD2s), and 60 controls (HCs) were recruited. Tract-based spatial statistics (TBSS) and diffusion connectometry were used to identify changes of WM pathways associated with PD. There were no significant differences in axial diffusivity, but HY1PDs exhibited greater fractional anisotropy (FA) and decreased mean and radial diffusivities (MD and RD) in callosal, projection, and association fibres than HCs and HY2PDs. Motor severity was inversely correlated with FA, but positively correlated with MD and RD in PD patients. Connectometry analysis also revealed increased WM density in the aforementioned tracts in PD patients, compared with HCs. Our study reveals WM enhancement, suggesting neural compensations in early PD. Longitudinal follow-up studies are warranted to identify the trajectory of WM changes alongside the progression of PD.

Neurite orientation dispersion and density imaging of the nigrostriatal pathway in Parkinson's disease: Retrograde degeneration observed by tract-profile analysis

“…Meanwhile, the fact that none of the indices correlated with the UPDRS-III indicates that diffusion alterations do not align with the worsening of motor function, possibly due to the effect of the medication [29]. This observation is in line with the findings of Zhang et al [8] and Wen et al [30], which reported correlations between DTI indices and UPDRS-III in the brain of untreated PD patients and a study by Lenfeldt et al [29], which showed no correlation in the SN and basal ganglia of treated PD patients. In contrast, Kamagata et al [12] revealed significant negative correlations between Vic and ODI in the SNpc and putamen with disease severity in a group of treated PD patients.…”

Age‐related changes in fiber tracts in healthy adult brains: A generalized q‐sampling and connectometry study

“…In addition, the connectometry analysis identified tract‐specific changes in connectivity in the bilateral RLIC, Ex, and PTR, and right SLF, SFO which were not identified by FA. Several studies have utilized connectometry to detect the associations between local WM connectivity patterns and study variables, such as body mass index, chronic stroke, apoA‐1, newly diagnosed Parkinson's disease, and major depression disorder . According to these studies, a connectometry analysis detects a greater number of tract changes correlated with study factors than DTI.…”

Connectometry evaluation in patients undergoing carotid endarterectomy: an exploratory study

“…As indicated above, previously published studies has investigated connectometry differences in other neurological diseases [24][25][26][27][28][29][30][31][32][33][34], adopting SDF as biomarker of investigation. SDF is a densitybased measurement of diffusion at different orientations and it measures the density of diffusing water, differently from other diffusivity measurements such as Fractional Anisotropy (FA), Apparent Diffusion Coefficient (ADC) and Radial Diffusivity.…”

“…The spin distribution function (SDF) is the parameter used for the analysis [23]. This method has been already used for example for the study of Parkinson disease [24][25][26][27][28][29][30], mood disorders [31,32], multiple sclerosis [33] and amyotrophic lateral sclerosis [34].…”