Working memory training improves cognitive efficiency in multiple sclerosis patients

La Esclerosis Múltiple (EM) es una enfermedad en la que la memoria de trabajo (MT) se encuentra comúnmente afectada. Estudiar la eficacia de un programa de entrenamiento en MT en pacientes de EM. 29 pacientes de EM Remitente-Recurrente fueron seleccionados para el estudio: 15 realizaron el entrenamiento en MT y 14 fueron seleccionados como grupo control. Todos los participantes fueron valorados a nivel neuropsicológico y se adquirieron imágenes de Resonancia Magnética funcional (RMf) durante la realización de la tarea 2 y 3-back (basal y post tratamiento-7 días). Los pacientes entrenados mejoraron su ejecución en 2 y 3-back (p<.001), tanto en aciertos como en tiempo de reacción (TR). Durante la realización de la tarea 2-back, los pacientes sin entrenamiento mostraron una mayor activación en el giro angular derecho (FWEc=125, p<.001) que correlaciona con el TR (r=.459, p<.05). También se observó una disminución de la actividad cerebral en el grupo de pacientes entrenados en el giro precentral derecho (FWEc=273, p<.01). Los resultados encontrados apoyan la eficacia del entrenamiento cognitivo en MT. Los pacientes de EM entrenados muestran una clara mejoría a nivel conductual asociada a un incremento de la eficiencia cognitiva, es decir, un menor uso de recursos cerebrales obteniendo una mejor ejecución.Multiple Sclerosis (MS) is a disease usually associated with a working memory (WM) impairment. Study the efficacy of a WM cognitive training program in MS patients. 29 relapsing-remitting MS patients were enrolled in the study: 15 underwent WM training and 14 were assigned to a control group. All participants were neuropsychologically assessed and Functional Magnetic Resonance imaging (fMRI) images were acquired during 2 and 3-back execution (baseline and post-training +7days). Training improved MS patients’ performance in 2 and 3-back, hence showing shorter reaction times (RT) and higher percentages of correct responses (p<.001). During 2-back performance, non-trained MS-patients exhibited a greater activation in in right angular gyrus (FWEc=125, p<.001) that was correlated to RT (r=.459, p<.05). Further, lower activation in right precentral gyrus in the trained MS-patients (FWEc=273, p<.01) was also found. The results obtained demonstrates the effectiveness of a WM training program in MS-patients. Trained MS-patients showed a marked improvement of WM performance and increased cognitive efficiency, i.e, using less cerebral resources to achieve higher performance

Supplementary Material for: Exploring Neural Efficiency in Multiple Sclerosis Patients during the Symbol Digit Modalities Test: A Functional Magnetic Resonance Imaging Study

<i>Background:</i> Reduced information-processing speed (IPS) is a primary cognitive deficit of multiple sclerosis (MS) patients. The neural efficiency hypothesis describes an inverse relationship between cognitive performance in a task and the amount of cognitive resources devoted to it. Previous studies have shown that the neural efficiency hypothesis provides an appropriate framework to explore cognitive dysfunction in neurological patients. <i>Objective:</i> The aim of this study was to explore the neural efficiency hypothesis regarding IPS capabilities in cognitively preserved MS patients. <i>Methods:</i> 16 MS patients and 17 healthy controls (HCs) were enrolled and neuropsychologically assessed. All participants also performed a functional magnetic resonance imaging (fMRI)-adapted version of the Symbol Digit Modalities Test (SDMT) at different interstimulus intervals (ISI: 1.5, 2, and 2.5 s). <i>Results:</i> MS patients only displayed lower SDMT performance when the ISI was set at 1.5 s. However, MS patients' normal SDMT performance at larger ISIs was achieved at the cost of increased brain activation, hence revealing that they were less cognitively efficient than the HCs. Regression analyses confirmed this conclusion by showing an opposite relationship between SDMT performance and the amount of neural resources recruited in the HC and MS groups. Thus, while a positive relationship between both variables was observed in MS patients, this correlation was negative for the HC group. <i>Conclusions:</i>MS patients require more cognitive resources than HCs to achieve a normal SDMT performance, then revealing that they are less efficient regarding IPS capabilities