Age and disability drive cognitive impairment in multiple sclerosis across disease subtypes

Abstract

MULTIPLE SCLEROSIS MSJ JOURNAL1258 journals.sagepub.com/home/msj BackgroundCognitive impairment (CI) is known to be present in all stages of multiple sclerosis (MS); however, the prevalence estimates vary considerably between studies, ranging from 40% to 65%. 1 The profile of CI in the overall MS population is now relatively well known, involving mainly complex attention, information processing speed, episodic memory, and executive functions. 1,2 Therefore, brief neuropsychological batteries for MS 3 and newly developed assessment tools 4 mainly focus on the assessment of these functions. However, few studies investigated the differences in the prevalence and profile of CI between the different MS disease subtypes, providing heterogeneous results. [5][6][7][8][9] Many of these studies included small clinical samples and focused mainly on relapsing remitting (RR) or progressive forms. Moreover, the association of CI with several clinical features, such as physical disability, sex, and disease duration, is not well established, since inconsistent results have been reported in the literature. [10][11][12][13] The heterogeneity of the published literature could be, at least in part, attributable to small sample size and dissimilarities in the clinical characteristics of the studies' samples. Exploring the independent effects of age, physical disability, disease duration, and disease subtype could prove central to provide a better understanding of the potential role and interaction of cognitive reserve, brain aging, and disease severity for determining CI in MS. The severity of impairment and the number of involved domains were significantly higher in SP and primary progressive multiple sclerosis (PPMS) than in CIS and RR. In multivariable logistic regression analysis, the presence of CI was significantly associated with higher Expanded Disability Status Scale (EDSS) and older age. Conclusion: CI is present in all MS subtypes since the clinical onset and its frequency is increased in the progressive forms, but these differences seem to be more associated with patient age and physical disability than to disease subtype per se.

Cognitive Impairment in Relapsing-Remitting Multiple Sclerosis Patients with Very Mild Clinical Disability

“…Some studies found a neuropsychological performance impairment in recently diagnosed patients [24, 25], in patients with CIS [7, 26, 27], and in RRMS patients at early stages of the disease with little or no disability [7, 22, 26, 28]. Otherwise, many studies reported a poorer neuropsychological performance in patients with chronic progressive or secondary progressive MS [1, 6, 7, 9] than in RRMS patients. These findings imply that the higher the disability in a more advanced stage of MS, the greater the cognitive impairment.…”

“…Cognitive dysfunction can be detected even at the earliest stages of the disease [6, 7]; nevertheless, its prevalence is higher in chronic progressive patients [7]. Longitudinal studies indicate that CI, if present, progresses over time [4, 8, 9].…”

“…Moreover, CI has a prognostic value as it indicates a shifting to a progressive phase and motor impairment [8, 10]. The disease course influences cognitive performance profiles: at the very early stage of the disease, that is, in clinically isolated syndrome (CIS) patients, the main domains involved are processing speed and executive functions [7, 9], while in the relapsing-remitting MS (RRMS) course, verbal and visual memory [7, 11] is also affected. Patients with a chronic progressive course, however, tend to exhibit a more frequent, severe, and widespread CI [7, 12].…”

“…Rao and colleagues [14] reported a slight but significant correlation between physical disability and the presence or degree of CI, whereas other studies failed to find any significant association [15]. More recently, a significant correlation of CI with physical disability was found in a heterogeneous sample of MS patients [7, 16]. …”

Patients with paediatric-onset multiple sclerosis are at higher risk of cognitive impairment in adulthood: An Italian collaborative study

“…This analysis was performed adjusting for the effect of age and EDSS that have found to be the independent predictors of CI in a previous analysis of the complete sample. 14 Furthermore, we tested the inclusion of disease duration in the logistic regression models adjusted for age, EDSS and POMS, given that a different disease duration is also expected in patients with POMS and AOMS of the same age.…”