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.

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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‐β = .301, p = .021). Furthermore, preservation of functional connectivity attenuated the impact of structural network WM tract disruption on cognition (β = −.513, p = .001, for cognitive processing speed; β = −.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.

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.