DESIGN: After screening clinical (rating disability by the means of the Expanded Disability Status Scale [EDSS] score), neurophysiological (e.g. evoked potential tests) and imaging examinations, MS patients and healthy subjects will undergo a neuropsychological evaluation using the Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS) and the Automated Neuropsychological Assessment Metrics (ANAM), and also a 3 Tesla magnetic resonance imaging (MRI). After 25% and after 50% of projected patients have been enrolled, distribution in MACFIMS will be evaluated to ensure that a broad spectrum of cognitive ability is represented. Cortical thickness, cortical lesions and white matter damage metrics (e.g. lesion load, diffusion tensor and magnetization transfer MRI measures) will be computed. In order to exclude the hypothesis that the presence of fatigue, anxiety and depression, normally occurring in MS patients, might interfere with their cognitive performance, thus acting as confounding factors, scales measuring fatigue and mental status will be administered in all subjects. Scores obtained on these scales will be used as covariates in each of the statistical analyses performed in the present study to account for their possible effects.