Cognitive-motor interference in multiple sclerosis and its relation to cognitive and motor impairment

Einleitung: Kognitiv-motorische Interferenz (CMI) erklärt Veränderungen der Leistung kognitiver oder motorischer Aufgaben, wenn diese gleichzeitig ausgeführt werden, im Vergleich zur alleinigen Ausführung. Sowohl bei gesunden Probandinnen und Probanden (HC) als auch bei Patientinnen und Patienten mit MS (PmMS) konnte eine CMI nachgewiesen werden kann, jedoch ist die Datenlage begrenzt und widersprüchlich. Das erschwert die genaue Bewertung des Einflusses von motorischen und kognitiven Beeinträchtigungen auf die CMI. Zielsetzung: Ziel der Studie war es, kognitive und motorische Leistungsveränderungen durch CMI bei PmMS und HC nachzuweisen, zwischen den Gruppen zu vergleichen und explorativ den Einfluss des motorischen und kognitiven Funktionsniveaus auf CMI zu analysieren. Methoden: Die analysierten Daten stammen aus einer Interventionsstudie und vier Beobachtungsstudien, die Einschlusskriterien variierten je nach Studie. Die Daten wurden nach vordefinierten Kriterien ausgewählt und es wurde eine systematische Qualitätskontrolle durchgeführt. Insgesamt wurden Daten von 113 PmMS und 42 HC analysiert. Erhoben wurden demografische Daten sowie Parameter zur Darstellung des motorischen und kognitiven Funktionsniveaus. In dem Versuchsaufbau wurde die motorische und kognitive Leistung im Stehen sowie nach Hinzunahme einer kognitiven, motorischen oder kombiniert kognitiv-motorischen Herausforderung erhoben. Im Anschluss wurden Veränderungen zwischen den jeweiligen Bedingungen berechnet und als Ratio zur Ausgangsbedingung ausgedrückt. Ergebnisse: Es zeigte sich bei HC und PmMS eine gleichwertige Veränderung der motorischen und kognitiven Leistung durch eine kognitive oder kombiniert kognitiv-motorische Herausforderung. Eine stärkere Abnahme der kognitiven Leistung korrelierte bei PmMS mit einem geringeren kognitiven und motorischen Funktionsniveau. Eine Zunahme im Körperschwanken durch eine kognitive oder kombiniert kognitiv-motorische Herausforderung trat vor allem bei PmMS und HC mit besserem kognitivem und motorischem Funktionsniveau auf. Eine Kombination beider Aufgaben führte insgesamt zu keiner weiteren Veränderung der motorischen Leistung bei gleichzeitiger Abnahme der kognitiven Leistung. Diskussion: Die Ergebnisse deuten darauf hin, dass der Einfluss der CMI kein krankheitsspezifischer Effekt ist, sondern vielmehr Ausdruck von individuell unterschiedlichen Adaptationsstrategien abhängig von dem jeweiligen motorischen und kognitiven Funktionsniveau ist. Es zeigte sich eine Priorisierung der motorischen Aufgabe bei PmMS mit niedrigerem kognitivem und motorischem Funktionsniveau, wahrscheinlich zur Vermeidung von Sturzereignissen. Dagegen erfolgte bei PmMS mit besserem kognitivem und motorischem Funktionsniveau eine Priorisierung der kognitiven Aufgabe zu Lasten der aktiven posturalen Kontrolle. Weitere Forschung könnte dazu beitragen, Subgruppen von Patientinnen und Patienten mit erhöhter Sturzneigung zu identifizieren.Introduction: Cognitive-motor interference (CMI) explains changes in the performance of cognitive or motor tasks when they are executed simultaneously compared to their individual execution. CMI has been observed in both healthy individuals (HC) and patients with multiple sclerosis (PmMS), but the available data is limited and contradictory, making it challenging to accurately assess the influence of motor and cognitive impairments on CMI. Objective: The aim of this study was to illustrate cognitive and motor performance changes due to CMI in PmMS and HC, compare them between groups and exploratively analyse the influence of motor and cognitive functioning on CMI. Methods: The analysed data derived from one intervention study and four observational studies, with inclusion criteria varying across the studies. The data were selected based on predefined criteria and a systematic quality control was conducted. A total of 113 PmMS and 42 HC were included in the analysis. Demographic data and parameters representing motor and cognitive functioning were collected. The experimental setup involved assessing motor and cognitive performance in a standing position with the addition of a cognitive, motor, or combined cognitive-motor challenge. Subsequently, changes between the respective conditions were calculated and expressed as a ratio to the baseline condition. Results: Comparable changes in motor and cognitive performance due to cognitive or combined cognitive-motor challenges were observed in both HC and PmMS. A significant reduction in cognitive performance correlated with lower levels of cognitive and motor functioning in PmMS. An increase in body sway due to a cognitive or combined cognitive-motor challenge was primarily observed in PmMS and HC with better cognitive and motor functioning. Combining both tasks did not result in further changes in motor performance overall but led to a decrease in cognitive performance. Discussion: The results suggest that the influence of CMI is not a disease-specific effect but rather reflects individually different adaptation strategies depending on the specific motor and cognitive functioning levels. PmMS with lower cognitive and motor functioning prioritized the motor task, likely to avoid falling events. In contrast, PmMS with better cognitive and motor functioning prioritized the cognitive task at the expense of active postural control. Further research could help identify subgroups of patients with an increased risk of falls

Association Between Fatigue and Motor Exertion in Patients With Multiple Sclerosis - a Prospective Study

Background: Fatigue in multiple sclerosis (MS) is conceived as a multidimensional construct. Objectives: This study aims to describe the changes of balance and gait parameters after 6 min of walking (6 MW) as potential quantitative markers for perceptions of state fatigue and trait fatigue in MS. Methods: A total of 19 patients with MS (17 with fatigue) and 24 healthy subjects underwent static posturography, gait analysis, and ratings of perceived exertion before and after 6 MW. Results: 6 MW was perceived as exhaustive, but both groups featured more dynamic comfortable speed walking after 6 MW. Shorter stride length at maximum speed and increased postural sway after 6 MW indicated fatigability of balance and gait in MS group only. While most changes were related to higher levels of perceived exertion after 6 MW (state fatigue), higher fatigue ratings (trait fatigue) were only associated with less increase in arm swing at comfortable speed. Further analysis revealed different associations of trait fatigue and performance fatigability with disability and motor functions. Performance fatigability was most closely related to the Expanded Disability Status Scale, while for trait fatigue, the strongest correlations were seen with balance function and handgrip strength. Conclusions: Fatigability of performance was closely related to perceptions of exertion after 6 MW (state fatigue) and disability in MS but distinct from fatigue ratings, conceived as trait fatigue. Our study identified postural sway, arm swing during gait, and hand grip strength as unexpected potential motor indicators of fatigue ratings in MS

MRI Markers and Functional Performance in Patients With CIS and MS: A Cross-Sectional Study

Introduction: Brain atrophy is a widely accepted marker of disease severity with association to clinical disability in multiple sclerosis (MS). It is unclear to which extent this association reflects common age effects on both atrophy and function. Objective: To explore how functional performance in gait, upper extremities and cognition is associated with brain atrophy in patients with Clinically Isolated Syndrome (CIS) and relapsing-remitting MS (RRMS), controlling for effects of age and sex. Methods: In 27 patients with CIS, 59 with RRMS (EDSS <= 3) and 63 healthy controls (HC), 3T MRI were analyzed for T2 lesion count (T2C), volume (T2V) and brain volumes [normalized brain volume (NBV), gray matter volume (NGMV), white matter volume (NWMV), thalamic volume (NThaIV)]. Functional performance was measured with short maximum walking speed (SMSW speed), 9-hole peg test (9HPT) and symbol digit modalities test (SDMT). Linear regression models were created for functional variables with stepwise inclusion of age, sex and MR imaging markers. Results: CIS differed from HC only in T2C and T2V. RRMS differed from HC in NBV, NGMV and NThaIV, T2C and T2V, but not in NWMV. A strong association with age was seen in HC, CIS and RRMS groups for NBV (r = -0.5 to -0.6) and NGMV (r = -0.6 to -0.8). Associations with age were seen in HC and RRMS but not CIS for NThaIV (r = -0.3; r = -0.5), T2C (r(s) = 0.3; r(s) = 0.2) and T2V (r(s) = 0.3; r(s) = 0.3). No effect of age was seen on NWMV. Correlations of functional performance with age in RRMS were seen for SMSW speed, 9HPTand SDMT (r = -0.27 to -0.46). Regression analyses yielded significant models only in the RRMS group for 9HPT, SMSW speed and EDSS. These included NBV, NGMV, NThaIV, NWMV, logT2V, age and sex as predictors. NThalV was the only MRI variable predicting a functional measure (9HPT(r)) with a higher standardized beta than age and sex (R2 = 0.36, p < 1e-04). Conclusion: Thalamic atrophy was a stronger predictor of hand function (9HPT) in RRMS, than age and sex. This underlines the clinical relevance of thalamic atrophy and the relevance of hand function as a clinical marker even in mildly disabled patients

Cognitive-motor interference in multiple sclerosis and healthy controls: results from single, dual, and triple task posturography

Aim: This article is based on our previous research, which was presented as a poster at the ECTRIMS Congress 2018 and published as a conference abstract (https://www.professionalabstracts.com/ectrims2018/iplanner/#/presentation/1698). Cognitive-motor interference (CMI) has been observed in both healthy controls (HC) and persons with multiple sclerosis (pwMS), but limited and contradictory data is making it difficult to assess the impact of motor and cognitive functioning levels on CMI. The aim of this study was to investigate CMI in pwMS and HC by means of a dual task postural paradigm, to compare them between groups and to analyse the influence of motor and cognitive functioning levels assessed with complementary instruments on observed CMI. Methods: The dual task posturography paradigm serves to quantify the impact of a cognitive (i.e., performing serial subtractions), a motor challenge (closing eyes), or both challenges combined (triple task) on body sway during standing in an upright position feet closed. The data analysed were acquired in one interventional and four observational studies and selected based on predefined criteria and by systematic quality control. A total of 113 pwMS and 42 HC were selected for analysis. Results: Comparable changes in motor and cognitive performance due to cognitive or combined cognitive-motor challenges were observed in both HC and pwMS. Combining both tasks did not result in further changes in motor performance but resulted in a decrease in cognitive performance. This reduction in cognitive performance with an additional motor challenge correlated with lower levels of cognitive and motor functioning in pwMS. Unexpectedly, an increase in body sway due to a cognitive or combined cognitive-motor challenges was primarily observed in pwMS and HC with better cognitive and motor functioning. Conclusions: The results suggest that dual-task effects are not disease-specific but rather reflect individually different adaptation strategies depending on the specific motor and cognitive functioning levels