title: Functional correlates of cognitive dysfunction in multiple sclerosis: A multicenter fMRI Study.
abstract: In this multicenter study, we applied functional magnetic resonance imaging (fMRI) to define the functional correlates of cognitive dysfunction in patients with multiple sclerosis (MS). fMRI scans during the performance of the N-back task were acquired from 42 right-handed relapsing remitting (RR) MS patients and 52 sex-matched right-handed healthy controls, studied at six European sites using 3.0 Tesla scanners. Patients with at least two abnormal (<2 standard deviations from the normative values) neuropsychological tests at a standardized evaluation were considered cognitively impaired (CI). FMRI data were analyzed using the SPM8 software, modeling regions showing load-dependent activations/deactivations with increasing task difficulty. Twenty (47%) MS patients were CI. During the N-back load condition, compared to controls and CI patients, cognitively preserved (CP) patients had increased recruitment of the right dorsolateral prefrontal cortex. As a function of increasing task difficulty, CI MS patients had reduced activations of several areas located in the fronto-parieto-temporal lobes as well as reduced deactivations of regions which are part of the default mode network compared to the other two groups. Significant correlations were found between abnormal fMRI patterns of activations and deactivations and behavioral measures, cognitive performance, and brain T2 and T1 lesion volumes. This multicenter study supports the theory that a preserved fMRI activity of the frontal lobe is associated with a better cognitive profile in MS patients. It also indicates the feasibility of fMRI to monitor disease evolution and treatment effects in future studies.
authors.affiliation: Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy; Department of Neurology, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Rocca
authors.forename: Paola
authors.initials: P
authors.lastname: Valsasina
authors.forename: Hanneke E
authors.initials: HE
authors.lastname: Hulst
authors.forename: Khaled
authors.initials: K
authors.lastname: Abdel-Aziz
authors.forename: Christian
authors.initials: C
authors.lastname: Enzinger
authors.forename: Antonio
authors.initials: A
authors.lastname: Gallo
authors.forename: Debora
authors.initials: D
authors.lastname: Pareto
authors.forename: Gianna
authors.initials: G
authors.lastname: Riccitelli
authors.forename: Nils
authors.initials: N
authors.lastname: Muhlert
authors.forename: Olga
authors.initials: O
authors.lastname: Ciccarelli
authors.forename: Frederik
authors.initials: F
authors.lastname: Barkhof
authors.forename: Franz
authors.initials: F
authors.lastname: Fazekas
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Tedeschi
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Arévalo
authors.forename: Massimo
authors.initials: M
authors.lastname: Filippi
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003072:Cognition Disorders / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000503:physiopathology*; D009483:Neuropsychological Tests; D012815:Signal Processing, Computer-Assisted
keywords: cognition; cognitive impairment; default mode network; fMRI; functional reserve; multiple sclerosis; prefrontal cortex