21 research outputs found
Cognitive impairment and its relation to imaging measures in multiple sclerosis: a study using a computerized battery.
BACKGROUND AND PURPOSE
Cognitive impairment (CI) is an important component of multiple sclerosis (MS) disability.
A complex biological interplay between white matter (WM) and gray matter (GM) disease
likely sustains CI. This study aims to address this issue by exploring the association
between the extent of normal WM and GM disease and CI.
METHODS
Cognitive function of 24 MS patients and 24 healthy volunteers (HVs) was studied using
the Automated Neuropsychological Assessment Metrics (ANAM) battery. WM focal lesions
and normal appearing WM (NAWM) volume in patients, cortical thickness (CTh) and deep
GM structure volumes in both patients and HVs were measured by high field strength
(3.0-Tesla; 3T) imaging.
RESULTS
An analysis of covariance showed that patients performed worse than HVs on Code Substitution
Delayed Memory (P = .04) and Procedural Reaction Time (P = .05) indicative of
reduced performance in memory, cognitive flexibility, and processing speed. A summary
score (Index of Cognitive Efficiency) indicating global test battery performance was also
lower for the patient group (P = .04). Significant associations, as determined by the
Spearman rank correlation tests, were noted between each of these 3 cognitive scores
and measures of NAWM volume [CDD-TP1(r = .609; P = .0035), PRO-TP1 (r = .456; P =
.029) and ICE (r = .489; P = .0129)], CTh (r = .5; P ≤ .05) and volume of subcortical
normal appearing GM (NAGM) structures (r = .4; P ≤ .04), but not WM lesions.
CONCLUSIONS
Both NAWM and NAGM volumes are related to CI in MS. The results highlight once again the
urgent need to develop pharmacological strategies protecting patients from widespread
neurodegeneration as possible preventive strategies of CI development
T(1) cortical hypointensities and their association with cognitive disability in multiple sclerosis
Objective: To assess the incidence of T(1) hypointense NLs by 3.0-Tesla magnetic resonance imaging (MRI) in patients with MS and examine neocortical lesion association with cognitive impairment. Methods: In this case-control study, 21 MS patients and 21 age-, sex- and years of education-matched healthy volunteers underwent: (i) a neuropsychological examination rating cognitive impairment (Minimal Assessment of Cognitive Function in MS); (ii) a 3.0-Tesla MRI inclusive of an isotropic 1.0 mm(3) three-dimensional inversion prepared spoiled gradient-recalled-echo (3D-IRSPGR) image and T(1)- and T(2)-weighted images. Hypointensities on 3D-IRSPGR lying in the cortex, either entirely or partially were counted and association between NLs and cognitive impairment investigated. Results: A total of 95 NLs were observed in 14 (66.7%) patients. NL+ patients performed poorer (p = 0.020) than NLpatients only on the delayed recall component of the California Verbal Learning Test. This difference lost statistical significance when a correction for white matter lesion volume was employed. Conclusions: Although T(1) hypointense NLs may be present in a relatively high proportion of multiple sclerosis patients, the impact that they have in cognitive impairment is not independent from white matter disease
Quality and Quantity of Diffuse and Focal White Matter Disease and Cognitive Disability of Patients with Multiple Sclerosis
BACKGROUND AND PURPOSE Using high-field magnetic resonance imaging (MRI), we investigated the relationships between white matter (WM) lesion volume (LV), normal-appearing WM (NAWM) normalized volume, WM-lesion and NAWM magnetization transfer ratios (MTRs), brain parenchyma fraction (BPF), and cognitive impairment (CI) in multiple sclerosis (MS). METHODS Twenty-four patients and 24 healthy volunteers (age, sex, and years of education-matched) underwent a 3.0 Tesla (3T) scan and evaluation of depression, fatigue, and CI using the Minimal Assessment of Cognitive Function in MS (MACFIMS) battery. RESULTS In this clinically relatively well-preserved cohort of patients (median score on the Expanded Disability Status Scale = 1.5), CI was detected on Symbol Digit Modalities Test (SDMT), California Verbal Learning Test-II (CVLT-II), and Controlled Oral Word Association Test. MT data were available in 19 pairs on whom correlation analyses were performed. Associations were seen between SDMT and normalized NAWM volume (P = .034, r = .502), CVLT-II long delay and normalized NAWM volume (P = .012, r = .563), WM-LV (P = .024, r = .514), and BPF (P = .002, r = .666). CONCLUSIONS The use of 3T MRI in a sample of clinically stable MS patients shows the importance of WM disease in hampering processing speed and word retrieval
Dislocation mechanisms and 3D twin architectures generate exceptional strength-ductility-toughness combination in CrCoNi medium-entropy alloy
Combinations of high strength and ductility are hard to attain in metals. Exceptions include materials exhibiting twinning-induced plasticity. To understand how the strength-ductility trade-off can be defeated, we apply in situ, and aberration-corrected scanning, transmission electron microscopy to examine deformation mechanisms in the medium-entropy alloy CrCoNi that exhibits one of the highest combinations of strength, ductility and toughness on record. Ab initio modelling suggests that it has negative stacking-fault energy at 0K and high propensity for twinning. With deformation we find that a three-dimensional (3D) hierarchical twin network forms from the activation of three twinning systems. This serves a dual function: conventional twin-boundary (TB) strengthening from blockage of dislocations impinging on TBs, coupled with the 3D twin network which offers pathways for dislocation glide along, and cross-slip between, intersecting TB-matrix interfaces. The stable twin architecture is not disrupted by interfacial dislocation glide, serving as a continuous source of strength, ductility and toughness