Exploring cognitive reserve in multiple sclerosis: New findings from a cross-sectional study

Introduction: The cognitive reserve (CR) hypothesis attempts to explain the discrepancy between brain damage and clinical manifestations in neurodegenerative diseases. Recently the concept of CR was applied to the multiple sclerosis (MS) model. Our aim is to investigate the impact of demographic and clinical variables on cognitive outcome in MS patients. Method: A total of 72 MS patients were assessed by Rao’s Brief Repeatable Battery of Neuropsychological Tests (BRB-N), Cognitive Reserve Index Questionnaire (CRIq), and high field magnetic resonance examination. We performed a multivariate linear regression analysis, including each cognitive test scores as dependent variables and CRI together with age, normalized brain volume (NBV), normalized cortical volume (NCV), expanded disability severity scale (EDSS) score, and disease duration as independent variables. Moreover, we assessed whether one of the CRI subscores (CRI–Education, CRI–WorkingActivity, CRI–LeisureTime) predicted cognitive performance more than the other. Finally, to assess the CR hypothesis in our sample, we conducted the same analyses including the interaction term CRI × NCV. Results: From the multiple regression analysis, it emerged that the CRI total score influenced sustained attention, concentration, information processing speed, and verbal learning. Among the three CRI subscores, CRI–Education and CRI–WorkingActivity had the most influence. Age and EDSS score were the other significant predictors. We did not find evidence for a moderation effect of CR on negative influence of atrophy on cognitive status. Conclusions: This study focused on the contribution of CR to predict neuropsychological outcome in MS. We used a new standardized questionnaire to provide a global index including three main source of CR: education, working activity, and leisure time activities. Our preliminary findings suggest that the CR is an important predictor of better performance on cognitive tests in MS patients. However, at this stage of the study, we are unable to confirm the CR hypothesis.