Differential cognitive impairment for diverse forms of multiple sclerosis

Behavioural responses and EEG signals were recorded during the experiment in three experimental groups: 1) a relapsing-remitting group (RRMS), 2) a benign multiple sclerosis group (BMS) and 3) a Control group. The paradigm employed was a spatial attention task with central cues (Posner experiment). The main aim was to observe the differences in the performance (behavioural variables) and in the latency and amplitude of the ERP components among these groups.Our data indicate that both MS groups showed poorer task performance (longer reaction times and lower percentage of correct responses), a latency delay for the N1 and P300 component, and a different amplitude for the frontal N1. Moreover, the deficit in the BMS group, indexed by behavioural and pyschophysiological variables, was more pronounced compared to the RRMS group.The present results suggest a cognitive impairment in the information processing in all of these patients. Comparing both pathological groups, cognitive impairment was more accentuated in the BMS group compared to the RMSS group. This suggests a silent deterioration of cognitive skills for the BMS that is not usually treated with pharmacological or neuropsychological therapy.Multiple sclerosis (MS) is a neurodegenerative disease of the Central Nervous System (CNS) in which early symptoms can appear in young adults between 20 and 40 years old. This condition damages the myelin shield of neurons in the brain, spinal cord and optical nerves. As a consequence of that, it produces sensory, motor and cognitive impairments that produce physical disabilities [1,2].Most MS patients present a clinical course in which exacerbations and remissions occur (85–90%). If this pattern is established, MS is classified as MS relapsing-remitting form (RRMS). After 10 years suffering this form of the disease, 50% of patients enter in a progressive phase of the illness defined as Secondary Progressive. The Primary Progressive form is characterized by a continuous progre