Cognitive trajectories in relapsing-remitting multiple sclerosis: Evidence of multiple evolutionary trends

Abstract

Background: Cognitive impairment (CI) frequently occurs in multiple sclerosis (MS) and is assumed to increase over time. However, recent studies have suggested that the evolution of cognitive status in patients with MS may be more heterogeneous than expected. Predicting CI remains also challenging, and longitudinal studies exploring the baseline determinants of cognitive performances are limited. No studies have explored the predictive value of patient-reported outcome measures (PROMs) regarding future CI.

Objective: To explore the evolutionary patterns of cognitive status in a cohort of RRMS patients initiating a new disease modifying treatment (DMT), and to determine whether PROMs may have a predictive value for future CI.

Methods: The present prospective study is a 12-month follow-up of a cohort of 59 RRMS patients who underwent yearly a comprehensive, multiparametric assessment combining clinical (with EDSS assessment), neuropsychological (BVMT-R, SDMT, CVLT-II), MRI-derived metrics and a set of self-reported questionnaires. Lesion and brain volumes were analyzed and processed by the automated MSmetrix® software (Icometrix®, Leuven, Belgium). Spearman's correlation coefficient was used to evaluate the association of collected variables. A longitudinal logistic regression analysis was performed to find baseline correlates of CI at 12 months (T1).

Results: A total of 33 patients (56%) were defined as cognitively impaired at baseline, and 20 (38%) were defined as impaired at follow-up after 12 months. The mean raw scores and Z-scores of all the cognitive tests were significantly improved at T1 (p < 0.05). There was a statistically significant improvement in most PROM scores at T1 (p < 0.05) in comparison with baseline scores. Among the variables assessed, lower education and physical disability level at baseline correlated with impaired SDMT (OR: 1.68, p = 0.01; OR: 3.10, p = 0.02, respectively) and impaired BVMT-R (OR: 4.08, p=<0.001; OR: 4.82, p = 0.001, respectively) at T1. Neither baseline PROMs nor MRI volumetric parameters were predictive of cognitive performances at T1.

Conclusions: These findings provide additional evidence that evolution of CI in MS may be a dynamic phenomenon and will not usually follow an inevitable, declining trajectory, and do not support the utility of PROMs in predicting CI in RRMS. The present study is still ongoing to determine whether our findings are confirmed at 2 and 3 years of follow-up.