Gray and white matter imaging: A biomarker for cognitive impairment in early Parkinson's disease?

The aim of this work was to investigate the cortical and white matter changes that underlie cognitive impairment in patients with incident Parkinson's disease (PD) disease using voxel-based morphometry and diffusion tensor imaging. Newly diagnosed nondemented PD (n = 125) and control subjects (n = 50) were recruited from the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation in Parkinson's Disease Study and completed cognitive assessments and 3T structural and diffusion tensor MR imaging. Voxel-based morphometry was performed to investigate the relationship between gray matter volume and cognitive ability. Microstructural white matter changes were assessed with diffusion tensor imaging measures of fractional anisotropy and mean diffusivity using tract-based spatial statistics. Increased mean diffusivity was observed bilaterally in subjects with PD, relative to controls (P = 0.019). Increased mean diffusivity was associated with performance on the semantic fluency and Tower of London tasks in frontal and parietal white matter tracts, including the cingulum, superior longitudinal fasciculus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus. There was no difference in total gray matter volume between groups; however, bilateral reductions in frontal and parietal gray matter volume were associated with reduced performance on measures of executive function in PD subjects. At the earliest stages of PD, regionally specific increases in central white matter mean diffusivity are present and suggest early axonal damage. Such changes are not accompanied by significant gray matter volume loss and are consistent with proposed models of pathological progression of the disease. Structural MRI, especially diffusion tensor imaging analysis, offers potential as a noninvasive biomarker reflecting cognitive impairment in PD.

Duncan GW ，Firbank MJ ，Yarnall AJ ，Khoo TK ，Brooks DJ ，Barker RA ，Burn DJ ，O'Brien JT ... -  《-》

Diffuse alterations in grey and white matter associated with cognitive impairment in Shwachman-Diamond syndrome: evidence from a multimodal approach.

Perobelli S ，Alessandrini F ，Zoccatelli G ，Nicolis E ，Beltramello A ，Assael BM ，Cipolli M ... -  《NeuroImage-Clinical》

Assessment of White Matter Lesions in Parkinson's Disease: Voxel-based Analysis and Tract-based Spatial Statistics Analysis of Parkinson's Disease with Mild Cognitive Impairment.

Application of diffusion tensor imaging (DTI) to explore the changes of FA value in patients with Parkinson's disease (PD) with mild cognitive impairment. 27 patients with PD were divided into PD with mild cognitive impairment (PD-MCI) group (n = 7) and PD group (n = 20). The original images were processed using voxel-based analysis (VBA) and tract-based spatial statistics (TBSS). The average age of pd-mci group was longer than that of PD group, and the course of disease was longer than that of PD group. Compared with PD group, the voxel based analysis-fractional anisotropy (VBA-FA) values of PD-MCI group decreased in the following areas: bilateral frontal lobe, bilateral temporal lobe, bilateral parietal lobe, bilateral subthalamic nucleus, corpus callosum, and gyrus cingula. Tract-based spatial statistics-fractional anisotropy (TBSS-FA) values in PD-MCI group decreased in bilateral corticospinal tract, anterior cingulum, posterior cingulum, fornix tract, bilateral superior thalamic radiation, corpus callosum(genu, body and splenium), bilateral uncinate fasciculus, bilateral inferior longitudinal fasciculus, bilateral superior longitudinal fasciculus, bilateral superior fronto-occipital fasciculus, bilateral inferior fronto-occipital fasciculus, and bilateral parietal-occipital tracts. The mean age of onset in the PD-MCI group was greater than that in the PD group, and the disease course was longer than that in the PD group. DTI-based VBA and TBSS post-processing methods can detect abnormalities in multiple brain areas and white matter fiber tracts in PD-MCI patients. Impairment of multiple cerebral cortex and white matter fiber pathways may be an important causes of cognitive dysfunction in PD-MCI.

Pu W ，Shen X ，Huang M ，Li Z ，Zeng X ，Wang R ，Shen G ，Yu H ... -  《-》

Altered functional connectivity in the default mode network is associated with cognitive impairment and brain anatomical changes in Parkinson's disease.

To assess whether functional neural connectivity is disrupted between the regions of the default mode network (DMN) in Parkinson's disease (PD) and how this connectivity is related to cognition, brain gray matter structure and white matter integrity and diffusivity. Thirty-seven PD patients and 16 healthy controls were evaluated, using resting-state functional magnetic resonance imaging (MRI), T1-weighted MRI, diffusion-weighted imaging and a battery of cognitive tests. Functional connectivity between the regions of the DMN, specifically in the precuneus, anterior and posterior cingulate, medial prefrontal and temporal and inferior parietal cortices was assessed with seed-to-voxel connectivity; gray matter volume and white matter values were determined using voxel-based morphometry and tract-based spatial statistics. Reduced functional connectivity was observed between the posterior cingulate and medial temporal lobe in PD. Lower cognitive performance, gray matter loss in posterior, medial temporal and parietal areas, and fractional anisotropy reduction in the white matter adjacent to DMN regions were also observed in PD patients compared with healthy controls. Lower DMN functional connectivity correlated with lower verbal and visual memory and visual abilities performance in PD. In addition, lower DMN functional connectivity correlated with lower gray matter volume in the posterior cingulate and precuneus, and with lower white matter fractional anisotropy of the inferior longitudinal and posterior cingulate fasciculi in PD. By combining different neuroimaging techniques and cognitive data, results showed that functional connectivity alteration between the regions of the DMN is associated with lower cognitive performance and gray and white matter abnormalities in PD.

Lucas-Jiménez O ，Ojeda N ，Peña J ，Díez-Cirarda M ，Cabrera-Zubizarreta A ，Gómez-Esteban JC ，Gómez-Beldarrain MÁ ，Ibarretxe-Bilbao N ... -  《-》

Mild cognitive impairment in Parkinson's disease is associated with a distributed pattern of brain white matter damage.

This study assesses the patterns of gray matter (GM) and white matter (WM) damage in patients with Parkinson's disease and mild cognitive impairment (PD-MCI) compared with healthy controls and cognitively unimpaired PD patients (PD-Cu). Three-dimensional T1-weighted and diffusion tensor (DT) magnetic resonance imaging (MRI) scans were obtained from 43 PD patients and 33 healthy controls. Cognition was assessed using a neuropsychological battery. Tract-based spatial statistics was applied to compare DT MRI indices between groups on a voxel-by-voxel basis. Voxel-based morphometry was performed to assess GM atrophy. Thirty PD patients were classified as MCI. Compared with healthy controls, PD-Cu and PD-MCI patients did not have GM atrophy. No region of WM damage was found in PD-Cu patients when compared with healthy controls. Relative to healthy controls and PD-Cu patients, PD-MCI patients showed a distributed pattern of WM abnormalities in the anterior and superior corona radiata, genu, and body of the corpus callosum, and anterior inferior fronto-occipital, uncinate, and superior longitudinal fasciculi, bilaterally. Subtle cognitive decline in PD is associated with abnormalities of frontal and interhemispheric WM connections, and not with GM atrophy. DT MRI might contribute to the identification of structural changes in PD-MCI patients prior to the development of dementia.

Agosta F ，Canu E ，Stefanova E ，Sarro L ，Tomić A ，Špica V ，Comi G ，Kostić VS ，Filippi M ... -  《-》