Disease characteristics and cognitive impairment in multiple sclerosis: A short-term observation is not enough.

Background: Multiple sclerosis (MS) is a disease that affects the central nervous system. One of its manifestations is cognitive impairment (CI), which can negatively affect the quality of life in people with MS (pwMS). This study aimed to investigate the nature of CI in MS and its associations with various disease characteristics.

Methods: Symbol Digit Modalities Test and cognitive tests adapted for the Slovak population as part of the NEUROPSY battery were used. For the assessment of depression, the Patient Health Questionnaire-9 was used. To assess the degree of functional disability, the Expanded Disability Status Scale, Timed 25-Foot Walk, and 9-Hole Peg Test were used. Plasma neurofilament light chain level (pNfL, a promising marker of neurodegeneration) was assessed. Variables in the CI vs. non-CI group were compared.

Results: In cognition, we observed statistically significant differences between the CI and the non-CI group in multiple measures. In the degree of functional disability, we found statistically significant differences between the groups in all measures. However, we found no statistically significant differences in depression, pNfL, type of disease-modifying therapy, or education. The Digit Span Forward (longest line) (OR: 0.375, 95%CI: 0.156-0.901, p = 0.028) and Trail Making Test-B (OR: 0.066, 95%CI: 0.013-0.339, p = 0.001) were the only independent variables in a model that predicted CI in binary logistic regression analysis.

Conclusion: Our cross-sectional study design failed to reveal the association of CI with various disease characteristics, or markers of neurodegeneration. For this purpose, longitudinal observation of pwMS, and future prospective studies are highly warranted.