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Recent evidence has shown the existence of a CNS 'waste clearance' system, defined as the glymphatic system. Glymphatic abnormalities have been described in several neurodegenerative conditions, including Alzheimer's and Parkinson's disease. Glymphatic function has not been thoroughly explored in multiple sclerosis, where neurodegenerative processes are intermingled with inflammatory processes. We aimed to investigate glymphatic system function in multiple sclerosis and to evaluate its association with clinical disability, disease course, demyelination and neurodegeneration, quantified using different MRI techniques. In this retrospective study, we enrolled 71 multiple sclerosis patients (49 relapsing-remitting and 22 progressive multiple sclerosis) and 32 age- and sex-matched healthy control subjects. All subjects underwent neurological and MRI assessment including high-resolution T1, T2 and double inversion recovery sequences, diffusion and susceptibility weighted imaging. We calculated the diffusion along perivascular space index, a proxy for glymphatic function, cortical and deep grey matter volume, white and cortical grey matter lesion volume and normal-appearing white matter microstructural damage. Multiple sclerosis patients showed an overall lower diffusion along perivascular space index versus healthy controls (estimated mean difference: -0.09, P = 0.01). Both relapsing-remitting and progressive multiple sclerosis patients had lower diffusion along perivascular space index versus healthy controls (estimated mean difference: -0.06, P = 0.04 for relapsing-remitting and -0.19, P = 0.001 for progressive multiple sclerosis patients). Progressive multiple sclerosis patients showed lower diffusion along perivascular space index versus relapsing-remitting multiple sclerosis patients (estimated mean difference: -0.09, P = 0.03). In multiple sclerosis patients, lower diffusion along perivascular space index was associated with more severe clinical disability (r = -0.45, P = 0.001) and longer disease duration (r = -0.37, P = 0.002). Interestingly, we detected a negative association between diffusion along perivascular space index and disease duration in the first 4.13 years of the disease course (r = -0.38, P = 0.04) without any association thereafter (up to 34 years of disease duration). Lower diffusion along perivascular space index was associated with higher white (r = -0.36, P = 0.003) and cortical (r = -0.41, P = 0.001) lesion volume, more severe cortical (r = 0.30, P = 0.007) and deep (r = 0.42, P = 0.001) grey matter atrophy, reduced fractional anisotropy (r = 0.42, P = 0.001) and increased mean diffusivity (r = -0.45, P = 0.001) in the normal-appearing white matter. Our results suggest that the glymphatic system is impaired in multiple sclerosis, especially in progressive stages. Impaired glymphatic function was associated with measures of both demyelination and neurodegeneration and reflects a more severe clinical disability. These findings suggest that glymphatic impairment may be a pathological mechanism underpinning multiple sclerosis. The dynamic interplay with other pathological substrates of the disease deserves further investigation., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Previous studies demonstrated an association between motor and cognitive performance in multiple sclerosis (MS). However, disease-related brain damage might represent a common substrate to both phenomena, which was not considered before., Objective: Aim of this study is to investigate whether the association between cognition and motor function is beyond structural damage in patients with MS., Methods: Eighty-one healthy controls and 106 relapsing-remitting (RR) MS patients underwent a 3.0 T MRI with quantification of T2-lesion volumes, T1-lesion volumes and normalized brain volumes. A functional examination [Nine-Hole Peg Test (9-HPT), Timed 25-Foot Walk test (T25FW) and Expanded Disability Status Scale] and a neuropsychological evaluation (Brief Repeatable Battery of Neuropsychological Tests) were also administered. Association between demographic, clinical, cognitive, MRI and functional measures were analysed with univariate analyses and hierarchical linear regression., Results: In RRMS patients, Spatial Recall Test and Symbol Digit Modalities Test were positively correlated with 9-HPT (p < 0.001) and T25FW (p ≤ 0.035); Paced Auditory Serial Addition Test (PASAT) correlated with 9-HPT (p ≤ 0.009). 9-HPT and T25FW were significantly associated with normalized brain volumes (p ≤ 0.016), T2- and T1-lesion volumes (p ≤ 0.009). Hierarchical regression models selected age and normalized deep gray matter volume as predictors of T25FW (adjusted-R 2  = 0.109). Younger age, female sex, higher normalized gray matter volume and higher PASAT 2″ scores predicted higher 9-HPT scores (adjusted-R 2  = 0.337)., Conclusions: In RRMS patients, deficit in information processing speed and executive function may contribute to hand motor dysfunction beyond the effect of structural disease-related burden, supporting the integration of motor and cognitive assessment in clinical settings., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Objective: To characterise in vivo the microstructural abnormalities of multiple sclerosis (MS) normal-appearing (NA) cortex and cortical lesions (CLs) and their relations with clinical phenotypes and disability using neurite orientation dispersion and density imaging (NODDI)., Methods: One hundred and seventy-two patients with MS (101 relapsing-remitting multiple sclerosis (RRMS), 71 progressive multiple sclerosis (PMS)) and 62 healthy controls (HCs) underwent a brain 3T MRI. Brain cortex and CLs were segmented from three-dimensional T1-weighted and double inversion recovery sequences. Using NODDI on diffusion-weighted sequence, intracellular volume fraction (ICV&#95;f) and Orientation Dispersion Index (ODI) were assessed in NA cortex and CLs with default or optimised parallel diffusivity for the cortex (D//=1.7 or 1.2 µm 2 /ms, respectively)., Results: The NA cortex of patients with MS had significantly lower ICV&#95;f versus HCs' cortex with both D// values (false discovery rate (FDR)-p <0.001). CLs showed significantly decreased ICV&#95;f and ODI versus NA cortex of both HCs and patients with MS with both D// values (FDR-p ≤0.008). Patients with PMS versus RRMS had significantly decreased NA cortex ICV&#95;f and ODI (FDR-p=0.050 and FDR-p=0.032) with only D//=1.7 µm 2 /ms. No CL microstructural differences were found between MS clinical phenotypes. MS NA cortex ICV&#95;f and ODI were significantly correlated with disease duration, clinical disability, lesion burden and global and regional brain atrophy (r from -0.51 to 0.71, FDR-p from <0.001 to 0.045)., Conclusions: A significant neurite loss occurs in MS NA cortex. CLs show a further neurite density reduction and a reduced ODI suggesting a simplification of neurite complexity. NODDI is relevant to investigate in vivo the heterogeneous pathology affecting the MS cortex., Competing Interests: Competing interests: Potential conflicts of interest outside the submitted work are as follows: PP received speaker honoraria from Biogen, Novartis, Merck Serono, Bristol Myers Squibb and ExceMED. EP received speaker honoraria from Biogen. RB and AF report no conflicts of interest. LC received speaker and consultant honoraria from ACCMED, Roche, BMS Celgene and Sanofi. MAR received speaker honoraria from Bayer, Biogen, Bristol Myers Squibb, Celgene, Genzyme, Merck Serono, Novartis, Roche and Teva, and received research support from the MS Society of Canada and Fondazione Italiana Sclerosi Multipla. MF is editor-in-chief of the Journal of Neurology, associate editor of Human Brain Mapping, associate editor of Radiology and associate editor of Neurological Sciences; received compensation for consulting services and/or speaking activities from Alexion, Almirall, Bayer, Biogen, Celgene, Eli Lilly, Genzyme, Merck-Serono, Novartis, Roche, Sanofi, Takeda and Teva Pharmaceutical Industries; and received research support from Biogen Idec, Merck-Serono, Novartis, Roche, Teva Pharmaceutical Industries, Italian Ministry of Health, Fondazione Italiana Sclerosi Multipla and ARiSLA (Fondazione Italiana di Ricerca per la SLA)., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

We aimed to investigate abnormal time-varying functional connectivity (FC) for thalamic sub-regions in multiple sclerosis (MS) and their clinical, cognitive and MRI correlates. Eighty-nine MS patients (49 relapsing-remitting [RR] MS; 40 progressive [P] MS) and 53 matched healthy controls underwent neurological, neuropsychological and resting state fMRI assessment. Time-varying connectivity (TVC) was quantified using sliding-window seed-voxel correlation analysis. Standard deviation of FC across windows was taken as measure of TVC, while mean connectivity across windows expressed static FC. MS patients showed reduced TVC vs controls between most of thalamic sub-regions and fronto-temporo-occipital regions. At the same time, they showed increased static FC between all thalamic sub-regions and structurally connected cortico-subcortical regions. TVC reduction was mainly driven by RRMS; while PMS exhibited a variable pattern of TVC abnormalities, characterized by reduced TVC between frontal/motor thalamic seeds and default-mode network areas and increased TVC vs controls/RRMS between posterior thalamic sub-regions and occipito-temporo-insular cortices, associated with severity of clinical disability. Compared with controls, both cognitively preserved and impaired patients showed reduced TVC between anterior thalamic sub-regions and frontal cortex. Cognitively impaired patients also showed increased TVC of the right postcentral thalamic sub-region with the cingulate cortex and postcentral gyrus vs both controls and cognitively preserved patients. Divergent patterns of TVC thalamic abnormalities were found between RRMS and PMS patients. TVC reduction in RRMS may represent the attempt of thalamic network to keep with stable connections. Conversely, increased TVC of posterior thalamic sub-regions characterized PMS and cognitively impaired MS, possibly reflecting maladaptive mechanisms., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Objective: The TRACER multicenter retrospective study aimed to collect data on treatment adherence in a real-life setting, in order to identify predictors of adherence at baseline., Methods: We recruited 384 relapsing-remitting (RR) multiple sclerosis patients with at least 12 months of use of RebiSmart®. This electronic device records the performed injections and assesses adherence as the percentage of 'not missing doses', through the connection to the iMed database. Subjects with at least 80% of completed doses at the 12 month of therapy were defined 'treatment adherents'., Results: After 12 months, 89.3% of patients were adherent; 93.2% of patients aged 26-40 years at baseline were adherent (vs 79% of the ≤25 and 87.5% of the ≥41 year olds; p = 0.006). Furthermore, 90.5% of patients with a baseline Expanded Disability Status Scale (EDSS) score <4 showed ≥80% adherence (vs 71.4% in those with EDSS score ≥4; p = 0.016). Fifty-four percent of the patients who were not adherent after 3 months were also not adherent after 12 months (OR 16.8; CI 95%:7.1-39.8)., Conclusions: Patients aged 26-40 years and with an EDSS score <4 at baseline were the most adherent. The status of 'treatment adherent' in the first 3 months was predictive of higher adherence in the long term.