Cognitive progression independent of relapse in multiple sclerosis.

BACKGROUND: Substantial physical-disability worsening in relapsing-remitting multiple sclerosis (RRMS) occurs outside of clinically recorded relapse. This phenomenon, termed progression independent of relapse activity (PIRA), is yet to be established for cognitive decline. METHODS: Retrospective analysis of RRMS patients. Cognitive decline was defined using reliable-change-index cut-offs for each test (Symbol Digit Modalities Test, Brief Visuospatial Memory Test-Revised, California Verbal Learning Test-II). Decline was classified as PIRA if the following conditions were met: no relapse observed between assessments nor within 9 months of cognitive decline. RESULTS: The study sample (n = 336) was 80.7% female with a mean (standard deviation (SD)) age, disease duration, and observation period of 43.1 (9.5), 10.8 (8.4), and 8.1 (3.1) years, respectively. A total of 169 (50.3%) subjects were cognitively impaired at baseline relative to age-, sex-, and education-matched HCs. Within subjects who experienced cognitive decline (n = 167), 89% experienced cognitive PIRA. A total of 141 (68.1%) cognitive decline events were observed independent of EDSS worsening. Cognitive PIRA was more likely to be observed with increased assessments (p < 0.001) and lower assessment density (p < 0.001), accounting for baseline clinical factors. CONCLUSION: These results establish the concept of cognitive PIRA and further our understanding of progressive cognitive decline in RRMS.

Paramagnetic rim lesions are associated with greater incidence of relapse and worse cognitive recovery following relapse.

BACKGROUND: Paramagnetic rim lesions (PRL) may be linked to relapse risk of people with relapsing-remitting multiple sclerosis (pwRRMS). OBJECTIVE: To determine the relationship between presence of PRL lesions and cognitive recovery after relapse. METHODS: PRL load was compared between acutely relapsing pwRRMS and matched stable pwRRMS controls (each group n = 21). In addition, cognitive recovery was compared between acutely relapsing pwRRMS with at least one PRL (PRL+) and those without any PRL (PRL-). RESULTS: Acutely relapsing pwRRMS had significantly greater prevalence and number of PRL (p = 0.004 and p = 0.003) compared with stable controls. These findings remained significant after adjusting for global neuroinflammatory burden (enhancing and non-enhancing lesions). In addition, acutely relapsing PRL + pwRRMS (n = 10) had worse recovery of verbal memory following relapse compared with acutely relapsing PRL - pwRRMS (n = 7; p = 0.027). CONCLUSION: These findings may partially explain previously suggested associations between presence of PRL with more severe disease course.

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.

Auditory Test of Processing Speed: Preliminary validation of a smartphone-based test of mental speed.

BACKGROUND: The Symbol Digit Modalities Test (SDMT) is a gold-standard measure of cognitive efficiency and processing speed for people with multiple sclerosis (PwMS) but relies on vision and oculomotor function. OBJECTIVES: To develop and validate a new processing speed test with minimal memory involvement and no eye function requirements. METHODS: We created an Auditory Test of Processing Speed (ATOPS). A total of 122 PwMS, of whom 33 were severely disabled (median Expanded Disability Status Scale 8.0) and 37 healthy volunteers (HVs), were enrolled. We assessed sensitivity to discriminate MS participants from HVs, convergent validity between ATOPS and SDMT, sensitivity to discriminate between cognitively impaired (CI) and cognitively preserved (CP) MS participants, and correlations with MS pathology (overall brain lesion burden). Acceptability was examined with completion rates and participant ratings of ATOPS. RESULTS: ATOPS discriminated PwMS from HVs (d = 0.739-0.856), correlated with SDMT (|r| = 0.528-0.587), discriminated between CI and CP PwMS (d = 0.623-0.776), and correlated with lesion burden (r = 0.332-0.436). All groups indicated high favorability of ATOPS and severely disabled MS patients could be assessed by ATOPS more frequently than by SDMT (100% vs. 72.4% completion). CONCLUSIONS: ATOPS is a novel, accessible, and acceptable cognitive processing speed test that may be useful in clinical and/or research settings.

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.

Cognitive function in severe progressive multiple sclerosis.

Cognitive impairment is common in multiple sclerosis and negatively impacts quality of life. Cognitive status has yet to be described in people with severe progressive multiple sclerosis, in whom conventional neuropsychological testing is exceptionally difficult. The objective for the study was to characterize cognitive performance in severe progressive multiple sclerosis and compare them with age-, sex- and disease duration-matched less disabled people with multiple sclerosis using a specifically developed auditory, non-motor test of attention/cognitive processing speed-Auditory Test of Processing Speed. Also, we aimed to determine the relationship between cognitive performance and MRI-based outcomes in these matched cohorts. The Comprehensive Assessment of Severely Affected Multiple Sclerosis study was carried out at the University at Buffalo and the Boston Home, a skilled nursing facility in Dorchester, MA. Inclusion criteria were age 30-80 years and expanded disability status scale 3.0-6.5 for community-dwelling and 7.0-9.5 for skilled nursing facility people with multiple sclerosis. The cognitive assessment was performed using the Brief International Cognitive Assessment for Multiple Sclerosis consisting of Symbol Digit Modalities Test, Brief Visuospatial Memory Test-Revised, California Verbal Learning Test-2nd edition along with Auditory Test of Processing Speed, Paced Auditory Serial Addition Test-3 second and Controlled Oral Word Association Test. MRI scans were retrospectively collected and analysed for lesion and volumetric brain measurements. The rate of completion and performance of the cognitive tests was compared between the groups, and the relationship with MRI measures was determined using sex, age and years of education-adjusted linear regression models. Significantly greater percentage of the severe multiple sclerosis group completed Auditory Test of Processing Speed when compared with the current gold standard of Symbol Digit Modalities Test (93.2% versus 65.9%). Severe progressive multiple sclerosis had worse cognitive performance in all cognitive domains with greatest differences for cognitive processing speed (Symbol Digit Modalities Test > Paced Auditory Serial Addition Test-3 second > Auditory Test of Processing Speed, Cohen's d < 2.13, P < 0.001), learning and memory (Cohen's d < 1.1, P < 0.001) and language (Controlled Oral Word Association Test with Cohen's d = 0.97, P < 0.001). Multiple cognitive domains were significantly associated with lower thalamic (standardized ß < 0.419, P < 0.006) and cortical (standardized ß < 0.26, P < 0.031) volumes. Specially designed (auditory) cognitive processing speed tests may provide more sensitive screening of cognitive function in severe progressive multiple sclerosis. The cognitive profile of severe multiple sclerosis is proportional to their physical outcomes and best explained by decreased grey matter volume.

Dynamic disability measures decrease the clinico-radiological gap in people with severely affected multiple sclerosis.

BACKGROUND: Expanded Disability Status Scale (EDSS) is limited when utilized in highly disabled people with multiple sclerosis (pwMS). OBJETIVE: To explore the relationship between disability measures and MRI outcomes in severely-affected pwMS. METHODS: PwMS recruited from The Boston Home (TBH), a specialized residential facility for severly-affected pwMS and University at Buffalo (UB) MS Center were assessed using EDSS, MS Severity Scale, age-related MSS, Scripps Neurological Rating Scale (SNRS) and Combinatorial Weight-Adjusted Disability Score (CombiWISE). In all scores except SNRS, higher score indicates greater disability. MRI measures of T1, T2-lesion volume (LV), whole brain, gray matter, medulla oblongata and thalamic volumes (WBV, GMV, MOV, TV) and thalamic dysconnectivity were obtained. RESULTS: Greatest disability differences between the TBH and UB pwMS were in SNRS (24.4 vs 71.9, p < 0.001, Cohen's d = 4.05) and CombiWISE (82.3 vs. 38.9, p < 0.001, Cohen's d = 4.02). In combined analysis of all pwMS, worse SNRS scores were correlated with worse MRI pathology in 8 out of 9 outcomes. EDSS only with 3 measures (GMV, MOV and TV). In severely-affected pwMS, SNRS was associated with T1-LV, T2-LV and WBV (not surviving false discovery rate (FDR) correction for multiple comparisons) whereas EDSS did not. CONCLUSION: Granular and dynamic disability measures may bridge the clinico-radiologcal gap present in severely affected pwMS.

Neuroimaging assessment of facility-bound severely-affected MS reveals the critical role of cortical gray matter pathology: results from the CASA-MS case-controlled study.

BACKGROUND: A subgroup of people with multiple sclerosis (pwMS) will develop severe disability. The pathophysiology underlying severe MS is unknown. The comprehensive assessment of severely affected MS (CASA-MS) was a case-controlled study that compared severely disabled in skilled nursing (SD/SN) (EDSS ≥ 7.0) to less-disabled (EDSS 3.0-6.5) community dwelling (CD) progressive pwMS, matched on age-, sex- and disease-duration (DDM). OBJECTIVES: To identify neuroimaging and molecular biomarker characteristics that distinguish SD/SN from DDM-CD progressive pwMS. METHODS: This study was carried at SN facility and at a tertiary MS center. The study collected clinical, molecular (serum neurofilament light chain, sNfL and glial acidic fibrillary protein, sGFAP) and MRI quantitative lesion-, brain volume-, and tissue integrity-derived measures. Statistical analyses were controlled for multiple comparisons. RESULTS: 42 SD/SN and 42 DDM-CD were enrolled. SD/SN pwMS showed significantly lower cortical volume (CV) (p < 0.001, d = 1.375) and thalamic volume (p < 0.001, d = 0.972) compared to DDM-CD pwMS. In a logistic stepwise regression model, the SD/SN pwMS were best differentiated from the DDM-CD pwMS by lower CV (p < 0.001) as the only significant predictor, with the accuracy of 82.3%. No significant differences between the two groups were observed for medulla oblongata volume, a proxy for spinal cord atrophy and white matter lesion burden, while there was a statistical trend for numerically higher sGFAP in SD/SN pwMS. CONCLUSIONS: The CASA-MS study showed significantly more gray matter atrophy in severe compared to less-severe progressive MS.

Cortical thickness and cognition in older people with multiple sclerosis.

BACKGROUND: The structural changes associated with cognitive performance in older people with multiple sclerosis (PwMS; age ≥ 50 years old) remain unknown. OBJECTIVE: To determine the relationship between whole-brain (WBV), thalamus as the largest deep gray matter nuclei, and cortex-specific volume measurements with both cognitive impairment and numerical performance in older PwMS. The main hypothesis is that cognitive impairment (CI) in older PwMS is explained by cortical thinning in addition to global and thalamic neurodegenerative changes. METHODS: A total of 101 older PwMS underwent cognitive and neuroimaging assessment. Cognitive assessment included tests established as sensitive in MS samples (Minimal Assessment of Cognitive Function in MS; MACFIMS), as well as those tests often utilized in Alzheimer's dementia studies (Wechsler's Memory Scale, Boston Naming Test, Visual Motor Integration and language). Cognitive impairment (CI) was based on -1.5 standard deviations in at least 2 cognitive domains (executive function, learning and memory, spatial processing, processing speed and working memory and language) when compared to healthy controls. WBV and thalamic volume were calculated using SIENAX/FIRST and cortical thickness using FreeSurfer. Differences in cortical thickness between CI and cognitively preserved (CP) were determined using age, sex, education, depression and WBV-adjusted analysis of covariance (ANCOVA). The relationship between domain-specific cognitive performance and cortical thickness was analyzed by linear regression models adjusted for age, sex, education, depression, WBV and thalamic volume. Benjamini-Hochberg-adjusted p-values lower than 0.05 were considered significant. RESULTS: The average age of the study population was 62.6 (5.9) years old. After adjustment, CI PwMS had significantly thinner left fusiform (p = 0.0003), left inferior (p = 0.0032), left transverse (p = 0.0013), and bilateral superior temporal gyri (p = 0.002 and p = 0.0011) when compared to CP PwMS. After adjusting for age, sex, education, depression WBV, and thalamic volume, CI status was additionally predicted by the thickness of the left fusiform (p = 0.001) and left cuneus gyri (p = 0.004). After the adjustment, SDMT scores were additionally associated with left fusiform gyrus (p < 0.001) whereas letter-based verbal fluency performance with left pars opercularis gyrus (p < 0.001). CONCLUSION: In addition to global and thalamic neurodegenerative changes, the presence of CI in older PwMS is additionally explained by the thickness of multiple cortical regions.

Cognitive Relapse in Multiple Sclerosis: New Findings and Directions for Future Research.

Multiple sclerosis (MS) is a chronic inflammatory, demyelinating disease of the central nervous system, often presenting with brain atrophy and cognitive impairment (CI). In the relapsing-remitting phenotype, cognitive performance is increasingly recognized to decline acutely during MS relapse, with varying degrees of recovery afterwards. Therefore, CI in MS may result from incomplete recovery from episodes of so-called "cognitive relapse", gradual neurodegeneration, or both. Among a variety of validated measures of cognitive performance, the Symbol Digit Modalities Test (SDMT) represents the most sensitive measure of cognitive decline and is easily translated to clinical practice. In fact, cognitive relapse identified using the SDMT has been reported in clinically relapsing cohorts as well as in individuals with no other neurological signs, suggesting that routine cognitive assessment may be necessary to fully appreciate the extent of a patient's disease activity. The aim of this narrative review is as follows: (1) to provide the historical context for neuropsychological assessment in MS, (2) to provide a summation of key studies describing the cognitive relapse phenomenon, and (3) to discuss current gaps in our knowledge and highlight avenues for future research.