Cognitive phenotypes predict response to restorative cognitive rehabilitation in multiple sclerosis.

BACKGROUND: Cognitive phenotyping may be useful for predicting rehabilitation response in multiple sclerosis. OBJECTIVE: To evaluate the association between cognitive phenotype(s) and response to restorative cognitive rehabilitation (RRCR). METHODS: In a post hoc retrospective analysis of the RRCR study including 51 multiple sclerosis patients, we evaluated both impairment within specific cognitive domains as well as overall global impairment severity to investigate their relationship to improvement following rehabilitation. RESULTS: Greater improvement in executive function was predicted by impairment within this domain as well as by having fewer impaired cognitive domains overall. Similar results were observed for visuospatial memory. CONCLUSIONS: Patients most likely to benefit from restorative cognitive rehabilitation may exhibit impairment within the domain of interest yet lower cognitive burden overall.

Functional alteration due to structural damage is network dependent: insight from multiple sclerosis.

Little is known about how the brain's functional organization changes over time with respect to structural damage. Using multiple sclerosis as a model of structural damage, we assessed how much functional connectivity (FC) changed within and between preselected resting-state networks (RSNs) in 122 subjects (72 with multiple sclerosis and 50 healthy controls). We acquired the structural, diffusion, and functional MRI to compute functional connectomes and structural disconnectivity profiles. Change in FC was calculated by comparing each multiple sclerosis participant's pairwise FC to controls, while structural disruption (SD) was computed from abnormalities in diffusion MRI via the Network Modification tool. We used an ordinary least squares regression to predict the change in FC from SD for 9 common RSNs. We found clear differences in how RSNs functionally respond to structural damage, namely that higher-order networks were more likely to experience changes in FC in response to structural damage (default mode R2 = 0.160-0.207, P < 0.001) than lower-order sensory networks (visual network 1 R2 = 0.001-0.007, P = 0.157-0.387). Our findings suggest that functional adaptability to structural damage depends on how involved the affected network is in higher-order processing.

Increased Stroke Risk Following Herpes Zoster Infection and Protection With Zoster Vaccine.

BACKGROUND: Studies evaluating stroke following varicella zoster virus (VZV) infection are limited, and the utility of zoster vaccination against this phenomenon is unclear. This study aimed to determine the risk of stroke 30 days following zoster infection and to evaluate the impact of zoster vaccinations on the risk of stroke in VZV-infected patients. METHODS: This retrospective case-control study was conducted from January 2010 to January 2020 utilizing nationwide patient data retrieved from the Veterans Affairs' Corporate Data Warehouse. RESULTS: A total of 2 165 505 patients ≥18 years of age who received care at a Veterans Affairs facility were included in the study, of whom 71 911 had a history of zoster infection. Zoster patients were found to have 1.9 times increased likelihood of developing a stroke within 30 days following infection (odds ratio [OR], 1.93 [95% confidence interval {CI}, 1.57-2.4]; P < .0001). A decreased risk of stroke was seen in patients who received the recombinant zoster vaccine (OR, 0.57 [95% CI, .46-.72]; P < .0001) or the live zoster vaccine (OR, 0.77 [95% CI, .65-.91]; P = .002). CONCLUSIONS: Patients had a significantly higher risk of stroke within the first month following recent herpes zoster infection. Receipt of at least 1 zoster vaccination was found to mitigate this increased risk. Vaccination may therefore be viewed as a protective tool against the risk of neurologic postinfection sequelae.

Detecting isolated cognitive relapses in persons with MS.

BACKGROUND: The existence of isolated cognitive relapses (ICRs) in persons with MS (PwMS) has been debated. OBJECTIVE: To examine relapses with decline on Symbol Digit Modalities Test (SDMT) but no change on Expanded Disability Status Scale (EDSS). METHODS: This 3-year prospective cohort study identified PwMS experiencing a relapse with decrease on SDMT. Participants with SDMT decline/stable EDSS were labeled "ICR," while those with a corresponding decrease on EDSS were classified "Relapse with Cognitive Decline (RCD)." Two definitions of SDMT decline were explored: (1) ⩾ 8 points, and (2) ⩾ 4 points. Logistic regression was used to analyze the relationship between ICR and RCD. RESULTS: The full cohort had 592 participants: 83 experienced relapses; 22 (26.5%) had an SDMT decrease of ⩾ 8 points; 14 (63.6%) met ICR criteria. Logistic regression (X2(1) = 5.112, p = 0.024) using demographics and disease characteristics explained 28.4% of the variance in ICR versus RCD. Only the MS Neuropsychological Questionnaire was associated with ICR (odds ratio (OR): 8.6; 95% confidence interval (CI): 1.1-16.4) 40 relapsing participants with SDMT decrease of ⩾ 4 points were identified: 26 (65%) had a stable EDSS (ICR). Logistic regression did not find any variable predictive of ICR. CONCLUSION: This prospective study demonstrates evidence of ICR in PwMS.

Staging and stratifying cognitive dysfunction in multiple sclerosis.

BACKGROUND: The sequence in which cognitive domains become impaired in multiple sclerosis (MS) is yet to be formally demonstrated. It is unclear whether processing speed dysfunction temporally precedes other cognitive impairments, such as memory and executive function. OBJECTIVE: Determine the order in which different cognitive domains become impaired in MS and validate these findings using clinical and vocational outcomes. METHODS: In a longitudinal sample of 1073 MS patients and 306 healthy controls, we measured performance on multiple, consensus-standard, neurocognitive tests. We used an event-based staging approach to model the sequence in which cognitive domains become impaired. Linear and logistic mixed-effects models were used to explore associations between stages of impairment, neurological disability, and employment status. RESULTS: Our model suggested that the order of impairments was as follows: processing speed, visual learning, verbal learning, working memory/attention, and executive function. Stage of cognitive impairment predicted greater neurological disability, ß = 0.16, SE = 0.02, p < 0.001, and probability of unemployment, ß = 1.14, SE = 0.001, p < 0.001. CONCLUSION: This is the first study to introduce a cognitive staging and stratification system for MS. Findings underscore the importance of using the Symbol Digit Modalities Test in routine screening for cognitive impairment and memory testing to assess patients later in disease evolution.

Interpreting change on the Symbol Digit Modalities Test in people with relapsing multiple sclerosis using the reliable change methodology.

BACKGROUND: The Symbol Digit Modalities Test (SDMT) is increasingly utilized in clinical trials. A SDMT score change of 4 points is considered clinically important, based on association with employment anchors. Optimal thresholds for statistically reliable SDMT changes, accounting for test reliability and measurement error, are yet to be applied to individual cases. OBJECTIVE: The aim of this study was to derive a statistically reliable marker of individual change on the SDMT. METHODS: This prospective, case-control study enrolled 166 patients with multiple sclerosis (MS). SDMT scores at baseline, relapse, and 3-month follow-up were compared between relapsing and stable patient groups. Using data from the stable group and three previously published studies, candidate thresholds for reliable decline were calculated and validated against other tests and a clinically meaningful anchor-cognitive relapse. RESULTS: Candidate thresholds for reliable decline at the 80% confidence level varied between 6 and 11 points. An SDMT change of 8 or more raw score points was deemed to offer the best balance of discriminatory power and external validity for estimating cognitive decline. CONCLUSION: This study illustrates the feasibility and usefulness of reliable change methodology for identifying statistically meaningful cognitive decline that could be implemented to identify change in individual patients, for both clinical management and clinical trial outcomes.

Thalamic Nuclei Volumes and Their Relationships to Neuroperformance in Multiple Sclerosis: A Cross-Sectional Structural MRI Study.

BACKGROUND: Although reduced thalamic volume is associated with multiple sclerosis (MS)-related clinical impairment, the role of individual thalamic nuclei remains poorly understood. PURPOSE/HYPOTHESIS: To test whether individual thalamic nuclei volumes are more strongly associated with clinical disability than the whole thalamic volume. STUDY TYPE: Retrospective analysis of a prospective dataset. SUBJECTS: A total of 108 MS patients and 48 age- and sex-matched healthy controls (HCs) FIELD STRENGTH: 3T. SEQUENCES: 3D T1 -weighted inversion recovery spoiled gradient echo; 2D T2 -weighted fluid-attenuated inversion recovery spin echo; 2D dual-echo proton density-weighted/T2 -weighted spin echo. ASSESSMENTS: Clinical assessments included the Expanded Disability Status Scale (EDSS), Nine-Hole Peg Test (9HPT), Timed 25-Foot Walk (T25FW), Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test-Revised (BVMTR), and the California Verbal Learning Test (CVLT2). FreeSurfer provided anterior, intralaminar, lateral, medial, ventral, posterior, and total volumes. STATISTICAL TESTS: False discovery rate-corrected partial correlations (controlling for age, sex, and education) to assess the relationships between volumes and neuroperformance. RESULTS: Compared to HCs, MS patients presented with lower thalamic nuclei volumes (P < 0.05) except for the intralaminar nucleus (P = 0.279) and scored worse on all neuroperformance scales (P ≤ 0.05) except for CVLT2 (P = 0.151). All nuclei except intralaminar were associated with EDSS (correlation coefficient range: -0.233 to -0.395), SDMT (range: 0.247-0.423), and 9HPT (range: -0.232 to -0.303) (all P < 0.05). BVMTR was associated with anterior (r = 0.319), lateral (r = 0.31), and medial (r = 0.304) volumes (all P < 0.05). T25FW correlated with ventral (r = -0.392) and total (r = -0.309) volumes (both P < 0.05), with the latter being significantly greater (P < 0.05). DATA CONCLUSION: Assessing individual nuclei volume can aid in unraveling the relationship between thalamic pathology and disparate aspects of MS-related disability. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.

Conscientiousness and deterioration in employment status in multiple sclerosis over 3 years.

BACKGROUND: Physical and cognitive symptoms of multiple sclerosis (MS) correlate with unemployment cross-sectionally. Prospective studies, rarely published, have not accounted for personality traits such as Conscientiousness. METHODS: In a 3-year study of 70 people with MS (PwMS) and 25 healthy controls (HCs), we evaluated employment status using online interviews capturing hours worked, negative work events, employee relations, and accommodations. Deteriorating employment status (DES) was defined as reduced employment (full-time to part-time or negative work events). In PwMS, we explored workplace accommodations, disclosure of disease status, and physical/psychological predictors of DES (e.g. Conscientiousness). RESULTS: At follow-up, DES was 0% in HCs and 25.7% in MS, and 62.7% of work-stable PwMS used at least one work accommodation, most frequently, flexible hours. At baseline, DES-PwMS had lower education (p = 0.009), lower Conscientiousness (p < 0.001), more fatigue (p = 0.033), and performed worse on Symbol Digit Modalities Test (p = 0.013), Brief Visuospatial Memory Test-Revised (p = 0.041), and Nine-Hole Peg Test (p = 0.046) relative to work-stable. The model predicting DES was significant (χ2(7) = 30.936, p < 0.001) and baseline Conscientiousness accounted for more variance in DES (p = 0.004) than other factors. Higher Conscientiousness PwMS were more likely to disclose their condition at work (p = 0.038). CONCLUSION: Accommodations for low Conscientiousness, flexible hours, and physical/cognitive rehabilitation may prevent DES.

Quantifying cognition and fatigue to enhance the sensitivity of the EDSS during relapses.

BACKGROUND: Cognition is affected by relapses in persons with multiple sclerosis (PwMS), yet the Expanded Disability Status Scale (EDSS) does not readily detect cognitive changes. OBJECTIVE: The objective of this study is to improve the detection of cognitive decline during relapses, by incorporating the Symbol Digit Modalities Test (SDMT) into the cerebral Functional System Score (CFSS) of the EDSS. METHODS: This prospective study recruited PwMS from three dedicated MS centers. All subjects had EDSS, SDMT, and Fatigue Severity Scale (FSS) administered. Subjects experiencing a relapse were assigned to the relapse group (RG). Matched controls from the larger cohort were assigned to the stable group (SG). RG and SG subjects underwent the same evaluation at relapse and 3 months later. Our main outcomes were a modified CFSS (m-CFSS) and modified EDSS (m-EDSS), incorporating SDMT and FSS, accounting for cognitive performance and fatigue rating, during relapse. RESULTS: The full cohort included 592 subjects; 80 qualified for RG and 72 were matched to the SG. The m-CFSS was significantly higher than CFSS at baseline (median = 2 vs. median = 0, p < 0.001) and relapse (median = 2 vs. median = 1, p < 0.001). The m-EDSS was higher than EDSS (median 3.0 vs. 2.5, p = 0.02) at relapse, where 35 RG subjects (43.8%) had higher m-EDSS than EDSS at relapse. CONCLUSION: This study demonstrates that incorporating the SDMT and FSS improves the accuracy of the EDSS, by accounting for cognitive changes, during relapse activity.

Recovery of cognitive function after relapse in multiple sclerosis.

BACKGROUND: Cognitive impairment is common in multiple sclerosis (MS) but its manifestation as acute disease activity is underappreciated. OBJECTIVE: The aim of this study is to examine recovery after MS relapse on multiple tests of cognitive and motor function and explore correlates of change with Expanded Disability Status Scale (EDSS), magnetic resonance imaging (MRI), and cognitive reserve. METHODS: Fifty relapsing group (RG) and matched stable participants were examined at baseline, during relapse, and at 3-month follow-up. Tests of cognitive processing speed (Symbol Digit Modalities Test (SDMT)) and consensus opinion measures of memory, ambulation, and manual dexterity were administered. All RG patients were treated with a 5-day course of Acthar Gel (5 mL/80 IU). RESULTS: In RG patients, SDMT declined from 55.2 to 44.6 at relapse and recovered to 51.7, a slope differing from stable controls (p = 0.001). A statistical trend (p = 0.07) for the same effect was observed for verbal memory and was significant for ambulation (p = 0.03). The Cerebral Function Score from the EDSS also changed in the RG and recovered incompletely relative to controls (p = 0.006). CONCLUSION: These results replicate earlier reports of cognitive worsening during relapse in MS. Clinically meaningful improvements followed relapse on SDMT and ambulation. Cognitive decline during relapse can be appreciated on neurological exam but not patient-reported outcomes.

Trait Conscientiousness predicts rate of longitudinal SDMT decline in multiple sclerosis.

BACKGROUND: Many people with multiple sclerosis (MS) exhibit cognitive decline over several years. Baseline differences may put people at greater risk for such decline. OBJECTIVE: To characterize rates of longitudinal cognitive decline and investigate baseline clinical predictors. METHODS: We report a retrospective analysis of 531 MS patients whose data were gleaned from a multi-study database, aggregated over 16 years. Linear mixed effects modeling was applied to estimate the average rate of decline on Symbol Digit Modalities Test (SDMT) performance and to predict rates of decline using baseline clinical variables. RESULTS: Participants exhibited an average estimated decline of 0.22 SDMT raw-score points/year (95% confidence interval (CI) (-0.32, -0.12)). We observed a significant main effect of time from baseline (t = -2.78, p = 0.006), test form (t = 2.13, p = 0.034), disease course (t = 2.91, p = 0.004), age (t = -2.76, p = 0.006), sex (t = -2.71, p = 0.007), subjective cognitive impairment (t = -2.00, p = 0.046), premorbid verbal intelligence (t = 5.14, p < 0.001), and trait Conscientiousness (t = 2.69, p = 0.008). A significant interaction emerged for Conscientiousness and time from baseline (t = 2.57, p = 0.011). CONCLUSION: Higher baseline trait Conscientiousness predicts slower rates of longitudinal cognitive decline in MS. This relationship, the average rate of decline, and practice effects can inform future research and clinical treatment decisions.

Trait Conscientiousness predicts rate of brain atrophy in multiple sclerosis.

BACKGROUND: Conscientiousness is a core personality trait with favorable prognosis in neuropsychiatric disease. OBJECTIVE: We aimed to determine whether baseline Conscientiousness predicts future brain atrophy in multiple sclerosis (MS) after accounting for demographic and basic clinical characteristics. METHODS: Trait Conscientiousness, clinical features, and Expanded Disability Status Scale (EDSS) were obtained at baseline. Lateral ventricle volume (LVV) was measured longitudinally. In a retrospective general linear mixed effects model, data from 424 patients were analyzed (mean 6 time-points, up to 15 years). RESULTS/CONCLUSION: We observed significant age and Conscientiousness by time-from-baseline interactions indicating that younger age and higher Conscientiousness are associated with reduced progression of brain atrophy.

Serum neurofilament light chain level associations with clinical and cognitive performance in multiple sclerosis: A longitudinal retrospective 5-year study.

BACKGROUND: A limited number of studies investigated associations between serum neurofilament light chain (sNfL) and cognition in persons with multiple sclerosis (PwMS). OBJECTIVE: To assess cross-sectional and longitudinal associations between sNfL levels, clinical, and cognitive performance in PwMS and age-matched healthy controls (HCs). MATERIALS: One hundred twenty-seven PwMS (85 relapsing-remitting MS/42 progressive MS), 20 clinically isolated syndrome patients, and 52 HCs were followed for 5 years. sNfL levels were measured using the single-molecule array (Simoa) assay and quantified in picograms per milliliter. Expanded Disability Status Scale (EDSS), walking, and manual dexterity tests were obtained. At follow-up, Brief International Cognitive Assessment for MS (BICAMS) was utilized. Cognitively impaired (CI) status was derived using HC-based z-scores. Age-, sex-, and education-adjusted analysis of covariance (ANCOVA) and regression models were used. Multiple comparison-adjusted values of q < 0.05 were considered significant. RESULTS: In PwMS, sNfL levels were cross-sectionally associated with walking speed (r = 0.235, q = 0.036), manual dexterity (r = 0.337, q = 0.002), and cognitive processing speed (CPS; r =-0.265, q = 0.012). Baseline sNfL levels predicted 5-year EDSS scores (r = 0.25, q = 0.012), dexterity (r = 0.224, q = 0.033), and CPS (r =-0.205, q = 0.049). CI patients had higher sNfL levels (27.2 vs. 20.6, p = 0.016) and greater absolute longitudinal sNfL increase when compared with non-CI patients (4.8 vs. 0.7, p = 0.04). CONCLUSION: Higher sNfL levels are associated with poorer current and future clinical and cognitive performance.

Preserved network functional connectivity underlies cognitive reserve in multiple sclerosis.

Cognitive reserve is one's mental resilience or resistance to the effects of structural brain damage. Reserve effects are well established in people with multiple sclerosis (PwMS) and Alzheimer's disease, but the neural basis of this phenomenon is unclear. We aimed to investigate whether preservation of functional connectivity explains cognitive reserve. Seventy-four PwMS and 29 HCs underwent neuropsychological assessment and 3 T MRI. Structural damage measures included gray matter (GM) atrophy and network white matter (WM) tract disruption between pairs of GM regions. Resting-state functional connectivity was also assessed. PwMS exhibited significantly impaired cognitive processing speed (t = 2.14, p = .037) and visual/spatial memory (t = 2.72, p = .008), and had significantly greater variance in functional connectivity relative to HCs within relevant networks (p < .001, p < .001, p = .016). Higher premorbid verbal intelligence, a proxy for cognitive reserve, predicted relative preservation of functional connectivity despite accumulation of GM atrophy (standardized-ß = .301, p = .021). Furthermore, preservation of functional connectivity attenuated the impact of structural network WM tract disruption on cognition (ß = -.513, p = .001, for cognitive processing speed; ß = -.209, p = .066, for visual/spatial memory). The data suggests that preserved functional connectivity explains cognitive reserve in PwMS, helping to maintain cognitive capacity despite structural damage.

Altered nuclei-specific thalamic functional connectivity patterns in multiple sclerosis and their associations with fatigue and cognition.

BACKGROUND: The thalamus, affected early in multiple sclerosis (MS), is a heterogeneous composition of functionally distinct nuclei and is associated with fatigue, cognition, and other outcomes. However, most previous functional imaging studies considered the thalamus only as a whole. OBJECTIVE: To investigate MS-related abnormalities in nuclei-specific thalamic functional connectivity (FC) and their associations with fatigue and cognitive outcomes. METHODS: Resting-state functional magnetic resonance imaging (fMRI) was analyzed in 64 MS patients and 26 healthy controls (HC). Whole-brain FC maps for four thalamic subregions seeds were computed for each subject. FC maps were compared between groups, and group by FC interaction effects were assessed for fatigue and cognitive measures. RESULTS: MS patients had decreased FC between the left medial thalamic nuclei and left angular gyrus and reduced FC between the left posterior thalamic nuclei and left supramarginal gyrus, as well as decreased right medial thalamic nuclei connectivity with bilateral caudate/thalamus and left cerebellar areas (p < 0.05 corrected). MS patients had increased FC between the left anterior thalamic nuclei and anterior cingulate cortex bilaterally. There were significant relationships between connectivity alterations and fatigue and cognitive measures between groups (p < 0.05 corrected). CONCLUSION: FC alteration is nuclei-specific and is differentially associated with fatigue and cognition.

White matter tract network disruption explains reduced conscientiousness in multiple sclerosis.

Quantifying white matter (WM) tract disruption in people with multiple sclerosis (PwMS) provides a novel means for investigating the relationship between defective network connectivity and clinical markers. PwMS exhibit perturbations in personality, where decreased Conscientiousness is particularly prominent. This trait deficit influences disease trajectory and functional outcomes such as work capacity. We aimed to identify patterns of WM tract disruption related to decreased Conscientiousness in PwMS. Personality assessment and brain MRI were obtained in 133 PwMS and 49 age- and sex-matched healthy controls (HC). Lesion maps were applied to determine the severity of WM tract disruption between pairs of gray matter regions. Next, the Network-Based-Statistics tool was applied to identify structural networks whose disruption negatively correlates with Conscientiousness. Finally, to determine whether these networks explain unique variance above conventional MRI measures and cognition, regression models were applied controlling for age, sex, brain volume, T2-lesion volume, and cognition. Relative to HCs, PwMS exhibited lower Conscientiousness and slowed cognitive processing speed (p = .025, p = .006). Lower Conscientiousness in PwMS was significantly associated with WM tract disruption between frontal, frontal-parietal, and frontal-cingulate pathways in the left (p = .02) and right (p = .01) hemisphere. The mean disruption of these pathways explained unique additive variance in Conscientiousness, after accounting for conventional MRI markers of pathology and cognition (ΔR2  = .049, p = .029). Damage to WM tracts between frontal, frontal-parietal, and frontal-cingulate cortical regions is significantly correlated with reduced Conscientiousness in PwMS. Tract disruption within these networks explains decreased Conscientiousness observed in PwMS as compared with HCs.

Longitudinal personality change associated with cognitive decline in multiple sclerosis.

We previously reported that personality and cognition were stable over 3 years in patients with multiple sclerosis (MS). This study examined whether a longer duration would reveal evidence of emerging personality dysfunction. The NEO Five-Factor Inventory and Brief International Cognitive Assessment for MS was used to assess personality and cognition, respectively. Patients were classified as "Cog Stable" or "Cog Decline" based on cognitive deterioration over 5 years. Extraversion and Conscientiousness declined across pooled groups. Follow-up of a group by time interaction found that decline in these traits was more evident in the Cog Decline group, demonstrating a link between personality and cognitive change.

Brain MRI disease burden and sex differences in cognitive performance of patients with multiple sclerosis.

BACKGROUND: Although there is evidence that shows worse cognitive functioning in male patients with multiple sclerosis (MS), the role of brain pathology in this context is under-investigated. OBJECTIVE: To investigate sex differences in cognitive performance of MS patients, in the context of brain pathology and disease burden. METHODS: Brain MRI, neurological examination, neuropsychological assessment (Brief International Cognitive Assessment in MS-BICAMS, and Paced Auditory Verbal Learning Test-PASAT), and patient-reported outcome questionnaires were performed/administered in 1052 MS patients. RESULTS: Females had higher raw scores in the Symbol Digit Modalities Test (SDMT) (57.0 vs. 54.0; p < 0.001) and Categorical Verbal Learning Test (CVLT) (63.0 vs. 57.0; p < 0.001), but paradoxically, females evaluated their cognitive performance by MS Neuropsychological Questionnaire as being worse (16.6 vs 14.5, p = 0.004). Females had a trend for a weaker negative correlation between T2 lesion volume and SDMT ([Formula: see text] = - 0.37 in females vs. - 0.46 in men; interaction p = 0.038). On the other hand, women had a trend for a stronger correlation between Brain Parenchymal Fraction (BPF) and a visual memory test (Spearman's [Formula: see text] = 0.31 vs. 0.21; interaction p = 0.016). All these trends were not significant after correction for false discovery rate. CONCLUSIONS: Although, females consider their cognition as worse, males had at a group level slightly worse verbal memory and information processing speed. However, the sex differences in cognitive performance were smaller than the variability of scores within the same sex group. Brain MRI measures did not explain the sex differences in cognitive performance among MS patients.

Identifying and understanding cognitive profiles in multiple sclerosis: a role for visuospatial memory functioning.

BACKGROUND: The heterogeneous nature of cognitive impairment in people with multiple sclerosis (PwMS) hampers understanding of the underlying mechanisms and developing patient-tailored interventions. We aim to identify and classify cognitive profiles in PwMS, comparing these to cognitive status (preserved versus impaired). METHODS: We included 1213 PwMS (72% female, age 45.4 ± 10.7 years, 83% relapsing-remitting MS). Cognitive test scores were converted to Z-scores compared to healthy controls for the functions: attention, inhibition, information processing speed (IPS), verbal fluency and verbal/visuospatial memory. Concerning cognitive status, impaired cognition (CI) was defined as performing at Z ≤ - 1.5 SD on ≥ 2 functions. Cognitive profiles were constructed using latent profile analysis on all cognitive functions. Cognitive profiles or status was classified using gradient boosting decision trees, providing the importance of each feature (demographics, clinical, cognitive and psychological functioning) for the overall classification. RESULTS: Six profiles were identified, showing variations in overall performance and specific deficits (attention, inhibition, IPS, verbal fluency, verbal memory and visuospatial memory). Across the profiles, IPS was the most impaired function (%CI most preserved profile, Profile 1 = 22.4%; %CI most impaired profile, Profile 6 = 76.6%). Cognitive impairment varied from 11.8% in Profile 1 to 95.3% in Profile 6. Of all cognitive functions, visuospatial memory was most important in classifying profiles and IPS the least (area under the curve (AUC) = 0.910). For cognitive status, IPS was the most important classifier (AUC = 0.997). CONCLUSIONS: This study demonstrated that cognitive heterogeneity in MS reflects a continuum of cognitive severity, distinguishable by distinct cognitive profiles, primarily explained by variations in visuospatial memory functioning.

Thalamic atrophy and dysconnectivity are associated with cognitive impairment in a multi-center, clinical routine, real-word study of people with relapsing-remitting multiple sclerosis.

BACKGROUND: Prior research has established a link between thalamic pathology and cognitive impairment (CI) in people with multiple sclerosis (pwMS). However, the translation of these findings to pwMS in everyday clinical settings has been insufficient. OBJECTIVE: To assess which global and/or thalamic imaging biomarkers can be used to identify pwMS at risk for CI and cognitive worsening (CW) in a real-world setting. METHODS: This was an international, multi-center (11 centers), longitudinal, retrospective, real-word study of people with relapsing-remitting MS (pwRRMS). Brain MRI exams acquired at baseline and follow-up were collected. Cognitive status was evaluated using the Symbol Digit Modalities Test (SDMT). Thalamic volume (TV) measurement was performed on T2-FLAIR, as well as on T1-WI, when available. Thalamic dysconnectivity, T2-lesion volume (T2-LV), and volumes of gray matter (GM), whole brain (WB) and lateral ventricles (LVV) were also assessed. RESULTS: 332 pwMS were followed for an average of 2.8 years. At baseline, T2-LV, LVV, TV and thalamic dysconnectivity on T2-FLAIR (p < 0.016), and WB, GM and TV volumes on T1-WI (p < 0.039) were significantly worse in 90 (27.1 %) CI vs. 242 (62.9 %) non-CI pwRRMS. Greater SDMT decline over the follow-up was associated with lower baseline TV on T2-FLAIR (standardized ß = 0.203, p = 0.002) and greater thalamic dysconnectivity (standardized ß = -0.14, p = 0.028) in a linear regression model. CONCLUSIONS: PwRRMS with thalamic atrophy and worse thalamic dysconnectivity present more frequently with CI and experience greater CW over mid-term follow-up in a real-world setting.