The link between resting-state functional connectivity and cognition in MS patients

Abstract

Objective: The objective of this paper is to explore differences in resting-state functional connectivity between cognitively impaired and preserved multiple sclerosis (MS) patients. Methods: Sixty MS patients and 18 controls were assessed with the Brief Repeatable Battery of Neuropsychological Tests (BRB-N). A global Z score of the BRB-N was obtained and allowed us to classify MS patients as cognitively impaired and cognitively preserved ( n = 30 per group). Functional connectivity was assessed by independent component analysis of resting-state networks (RSNs) related to cognition: the default mode network, left and right frontoparietal and salience network. Between-group differences were evaluated and a regression analysis was performed to describe relationships among cognitive status, functional connectivity and radiological variables. Results: Compared to cognitively preserved patients and healthy controls, cognitively impaired patients showed a lesser degree of functional connectivity in all RSNs explored. Cognitively preserved patients presented less connectivity than the control group in the left frontoparietal network. Global Z scores were positively and negatively correlated with brain parenchymal fraction and lesion volume, respectively. Conclusion: Decreased cognitive performance is accompanied by reduced resting state functional connectivity and directly related to brain damage. These results support the use of connectivity as a powerful tool to monitor and predict cognitive impairment in MS patients.

Cerebral Autoregulation and Brain Networks in Occlusive Processes of the Internal Carotid Artery

“…38 The FPN has been associated with executive task performance 39 and its connectivity decreases, for example, in patients with multiple sclerosis who frequently present with impaired executive functions. 40 Corresponding to lower RSFC in these networks, both episodic memory and executive scores were lower in our patients group compared with controls. In sum, we provide evidence that unilateral decreases of VMR are characterized by both ipsilateral and bilateral alterations in connectivity between major nodes of the DMN and the FPN.…”

Increased regional gray matter atrophy and enhanced functional connectivity in male multiple sclerosis patients

“…Increased FC has previously been understood as a secondary neuropathological sign of MS progresion [14] or as a compensatory mechanism for early MS neuropathological changes [12,13]. Only the later interpretation would be coherent with several additional findings of our study: 1) the direct correlation found between FC and GM atrophy; 2) the fading gender-related differences in FC when GM volume was introduced as a covariate; 3) lack of differences in neurological and neuropsychological performance (see Table 1) between Male-and Female-MSp despite their different degrees of GM atrophy in several brain regions; 4) the positive association of remaining GM volume and FC scores with attentional capabilities in Male-but not in Female-MSp.…”

“…Increased FC resulting from GM atrophy in MS patients has been interpreted in two different ways: Either as maladaptive and, as such, a sign of MS neuropathological progression [14] or, to the contrary, as a compensatory mechanism promoting normal cognitive competence of MS patients at initial stages of the disease [12,13]. To find out which of these two alternatives applies to our observations, we analyzed the relationship between FC, GM volume and cognitive performance in Male-and Female-MSp.…”

“…As previous studies [12,13] have suggested that increased FC is a secondary response to primary MS-related neuropathological changes in GM, we explored the relationship between both variables. We found that the FC scores on the three pathways, where we observed gender differences within MS patients ( Figure 1B), were inversely related to the GM volume in the two frontal areas, where the Male-and Female-MS subgroups also differed ( Figure 1A).…”

Exploring Neural Efficiency in Multiple Sclerosis Patients during the Symbol Digit Modalities Test: A Functional Magnetic Resonance Imaging Study

“…Indeed, a growing number of studies have revealed that MS patients might retain apparently normal cognitive performance by increasing the number of neural resources, at least in early stages of the disease [8,9,10,11,12]. Therefore, these and other studies have advocated the need for coupling neuropsychological assessments with neuroimaging techniques, and for understanding the MS cognitive status as part of the “neural efficiency hypothesis” [13,14].…”