Cognitive dysfunction in patients with relapsing-remitting multiple sclerosis

Abstract

Cognitive dysfunction is considered one of the clinical markers of multiple sclerosis (MS). However, in the literature there are inconsistent reports on the prevalence of cognitive dysfunction, and separate data for the relapsing-remitting (RR) type of the disease are not always presented. In this study, we submitted 461 RRMS patients to a battery of neuropsychological tests to investigate their impairment in various cognitive domains. As a consequence of the exclusion criteria, the sample is not fully representative of the entire population of RRMS patients. In this selected sample, when only the eight scores of a core battery (Mental Deterioration Battery) were considered (with respective cutoffs), it emerged that 31% of the patients were affected by some degree of cognitive deficit. In particular, 15% had mild, 11.2% moderate and 4.8% had severe impairment. Information processing speed was the most frequently impaired area, followed by memory. When two other tests (SDMT and MCST) were added and cognitive domains were considered, it emerged that 39.3% of the patients were impaired in two or more domains. When four subgroups were obtained by means of cluster analysis and then compared, it emerged that information processing speed and memory deficits differentiated the still cognitively unimpaired from the mildly impaired MS patients. Significant associations were found between cognitive and clinical characteristics. However, due to the large sample size, clinically irrelevant relationships may also have emerged. Even with the limitations imposed by the sample selection and the possible underestimation of the prevalence and severity of cognitive dysfunction, these results seem to provide further evidence that information processing speed deficit may be an early and important marker of cognitive impairment in MS patients.

Selective Decline in Information Processing in Subgroups of Multiple Sclerosis: An 8-Year Longitudinal Study

“…Typically, cognitive speed is affected markedly and early in the disease course [4, 8, 9]. Other cognitive functions may be affected to a lesser extent and later during the disease course as exemplified by memory [4, 10, 11] and verbal abilities [12, 13]. Frequently, also executive functions like verbal fluency have been reported to be impaired in MS [5, 14, 15].…”

“…The frequency of cognitive dysfunction has been estimated to be about 50% in the MS patient population [5,6,7]. Typically, cognitive speed is affected markedly and early in the disease course [4, 8, 9]. Other cognitive functions may be affected to a lesser extent and later during the disease course as exemplified by memory [4, 10, 11] and verbal abilities [12, 13].…”

“…Cognitive impairment can be an early symptom in MS as compared to healthy controls [1,2,3,4]. The frequency of cognitive dysfunction has been estimated to be about 50% in the MS patient population [5,6,7].…”

Integration of Cognitive Impairment in the Expanded Disability Status Scale of 215 Patients with Multiple Sclerosis

“…However, prevalence estimates of cognitive dysfunction vary widely, ranging from 40 to 70% of MS patients [1,2], with a recent study presenting a prevalence estimate of 31% in a population of 461 relapsing-remitting patients [3]. To date, most authors agree that these patients have disturbances of memory, executive function, language, or visuospatial abilities [4,5,6].…”

A "Conceptual Nervous System" for multiple sclerosis.

“…Neuropsychological deficits in MS may occur early in the course of the disease (Amato et al, 2010), being sometimes very subtle, difficult to detect, and perceptible in 40-70% of patients in transversal studies (McIntosh-Michaelis et al, 1991;Rao, Leo, Bernardin, & Unverzagt, 1991). Interindividual variability of deficits restricts criterion validity of neuropsychological tests and their accuracy to discriminate individuals with MS from controls (Nocentini et al, 2006;Rao et al, 1991). Patients with predominantly spinal forms of the disease may present only mild cognitive impairment (Pelosi, Geesken, Holly, Hayward, & Blumhardt, 1997).…”