White matter alterations in Parkinson’s disease with normal cognition precede grey matter atrophy

I Rektor,A Svátková,L Vojtíšek,I Zikmundová,J Vaníček,A Király,N Szabó

doi:10.1016/j.parkreldis.2017.11.030

Abstract

INTRODUCTION While progressive MRI brain changes characterize advanced Parkinson's disease (PD), little has been discovered about structural alterations in the earliest phase of the disease, i.e. in patients with motor symptoms and with normal cognition. Our study aimed to detect grey matter (GM) and white matter (WM) changes in PD patients without cognitive impairment. METHODS Twenty PD patients and twenty-one healthy controls (HC) were tested for attention, executive function, working memory, and visuospatial and language domains. High-resolution T1-weighted and 60 directional diffusion-weighted 3T MRI images were acquired. The cortical, deep GM and WM volumes and density, as well as the diffusion properties of WM, were calculated. Analyses were repeated on data flipped to the side of the disease origin. RESULTS PD patients did not show any significant differences from HC in cognitive functioning or in brain volumes. Decreased GM intensity was found in the left superior parietal lobe in the right (p<0.02) and left (p<0.01) flipped data. The analysis of original, un-flipped data demonstrated elevated axial diffusivity (p<0.01) in the superior and anterior corona radiata, internal capsule, and external capsule in the left hemisphere of PD relative to HC, while higher mean and radial diffusivity were discovered in the right (p<0.02 and p<0.03, respectively) and left (p<0.02 and p<0.02, respectively) in the fronto-temporal WM utilizing flipped data. CONCLUSIONS PD patients without cognitive impairment and GM atrophy demonstrated widespread alterations of WM microstructure. Thus, WM impairment in PD might be a sensitive sign preceding the neuronal loss in associated GM regions.

Highlights

While progressive MRI brain changes characterize advanced Parkinson’s disease (PD), little has been discovered about structural alterations in the earliest phase of the disease, i.e. in patients with motor symptoms and with normal cognition
The analysis of original, un-flipped data demonstrated elevated axial diffusivity (p
Distinct levels of cognitive deficits are defined in PD, including mild cognitive impairment (PD-MCI) and PD dementia (PDD), careful psychological testing could reveal a restricted deficit of certain cognitive functions even in the earliest stages of PD [1,2,3]

Summary

Methods

Twenty PD patients and twenty-one healthy controls (HC) were tested for attention, executive function, working memory, and visuospatial and language domains. We recruited 25 PD patients from the Brno Movement Disorders Centre and 21 age- and gender-matched healthy controls (mean age: 57.9±7.24 years, age range: 41–71 years, 8 male). The patients that did not present any evident cognitive impairment at clinical examination were included to the study and were further examined utilizing detailed psychological tests. Five patients were excluded because of MRI technical problems (movement artefacts, restricted field of view, claustrophobia), drop-out rate was 20%. Twenty PD patients (mean age: 61.9 ±7.63; age range: 48–72 years, 11 male) that have included to the study were in the early stages of the disease with slight to moderate motor impairment (Hoehn-Yahr stage 1–1.5) and disease duration up to 5 years.

Results

Discussion

Conclusion