Spectrum of Cognitive Impairment in Patients with Multiple Sclerosis

Abstract

Introduction. Cognitive impairment (CI) is a common manifestation of multiple sclerosis (MS), which significantly affects patients’ daily life and professional activity. Despite the development of methods to screen MS patients for CI, data on its prevalence in the Russian population are still lacking. Aim: to comprehensively assess cognitive functions in patients with different types of MS. Materials and methods. The study included MS patients who did not have any other possible causes of CI and no diseases or conditions that confounded this assessment. CI was determined using the Brief International Cognitive Assessment in Multiple Sclerosis (BICAMS) test battery and the Stroop test as a decrease in the scores below the mean by at least 1.5 standard deviations. CI was subjectively assessed using the Perceived Deficit Questionnaire; fatigue was subjectively assessed using the Modified Fatigue Impact Scale (MFIS). The Mann–Whitney test and Fisher’s exact test were used for comparison, and the Spearman test was used to evaluate correlations. Results. We evaluated 77 MS patients (30 men; age 40 [30; 48] years; 47 with relapsing-remitting MS, 30 with progressive MS). CI incidence was 23.4% in patients with relapsing-remitting MS and 77% in patients with progressive MS, while multi-domain CI was statistically significantly more common in patients with progressive MS. Impairment of processing speed was the most common. Patients with relapsing-remitting MS and CI were statistically significantly older and had longer disease duration than those without CI. There was a statistically significant correlation of subjective CI severity with MFIS scores but not with testing results. Conclusion. CI incidence in MS patients was relatively high with greater severity and involvement of more domains in patients with progressive MS. No correlation was found between subjective and objective CI assessment results, which may suggest that patients underestimated their deficit.