Event Related Brain Potentials (ERP) Could Not Assess the Risk of Cognitive Impairment in Relapse-Remitting Multiple Sclerosis (RRMS)

Abstract

Objectives: The first objective of our study was to determine differences between groups of patients receiving disease modifying therapy (DMTs) (INFβ-1a and INFβ-1b), patients without DMTs and a control group, in terms of neuropsychological tests and event-related brain potentials (ERP). The second objective was to determine factors that may serve to assess the risk of cognitive impairment in patients with relapsing remitting multiple sclerosis (RRMS). Methods: A total of 81 RRMS patients (mean age 41.09 ± 8.71 years old, 51 women, mean disease duration 133.05 ± 76.56 months) and 32 healthy controls participated in the study. Cognitive functions were evaluated using a standard PASAT-3, the symbol digit modality test (SDMT) and ERP. Results: There were statistically significant differences between the mean values for parietal (Pz) (p ≤ 0.05) and central (Cz) latency (p<0.05) between the four groups of study participants. RRMS increased the risk of cognitive impairment approximately 3.5 fold. Each year of age raised the risk of cognitive impairment by 6.0%. Each unit increase in level of education reduced the risk of cognitive impairment approximately 2.5 fold. Increase in reaction time (RT) Cz by 1 ms elevated the risk of cognitive impairment by 0.5%. Conclusions: There were statistically significant differences between the mean values of Pz and Cz latency between the four groups of study participants. Factors that may be used to assess the risk of developing cognitive impairment in patients with RRMS include age, education level, and RT Cz. However, ERP (latency and amplitude) did not independently assess the risk of cognitive impairment in RRMS patients.