Imaging Poster Presentation

P0578 - Five years functional connectivity reorganization without clinical or cognitive decline in MS (ID 755)

Speakers
  • E. Høgestøl
Authors
  • E. Høgestøl
  • S. Ghezzo
  • G. Nygaard
  • T. Espeseth
  • P. Sowa
  • M. Beyer
  • H. Harbo
  • L. Westlye
  • H. Hulst
Presentation Number
P0578
Presentation Topic
Imaging

Abstract

Background

Multiple sclerosis (MS) is a disease characterized radiologically by the accumulation of lesions in grey and white matter over time throughout the CNS. Accumulating evidence has demonstrated abnormal patterns of brain functional connectivity (FC) in MS patients as compared to healthy controls (HCs). A longitudinal approach that accounts for all alterations in FC following structural damage in MS is warranted to better understand the complex interplay between disease progression and FC reorganization.

Objectives

1) To assess fMRI-based FC anomalies in early MS 2) To determine the relation between FC changes and structural brain damage due to disease progression 3) To study the association between FC changes and cognitive and physical disability.

Methods

Structural MRI and resting-state fMRI were acquired from 76 early relapsing-remitting MS patients at baseline (average disease duration 71.7 months ± 63) and after five years. Ninety-four HCs matched for age and sex were included at baseline. Independent component analysis (ICA) and network modelling were used to measure FC. FC variation was related to expanded disability status scale, timed 25-foot walk test, 9 hole peg test and neuropsychological outcomes. Brain and lesion volumes were quantified using standard methods. We used the 25 independent components obtained from ICA to estimate the longitudinal stability of the brain functional connectome as a proxy for functional reorganization over time. We computed the stability of the brain functional connectome for each MS patient by vectorizing each participant’s whole-brain connectivity matrix. Then, we calculated the within subjects Spearman correlation coefficient between fMRI at baseline and follow-up, obtaining a measure of whole-brain connectome stability that is sensitive to all changes in FC in the follow-up period.

Results

The MS subjects (71% females, mean age 35.3 ± 7.3) were clinically and cognitively stable. Compared to HCs, FC abnormalities were detected within networks and in single connections, mainly in the default mode network and frontoparietal areas, in patients with early MS at baseline. Over time, FC was relatively invariable, but changes in FC were associated with progression of brain atrophy (ρ = 0.39, p = .06). No significant relationship with clinical and cognitive measures or lesion load was detected.

Conclusions

We used the stability of the brain functional connectome as a proxy for FC reorganization. Patients with MS showed altered FC in the early stages of the disease, with FC abnormalities being bidirectional (i.e. increased and decreased FC). Over time, changes in FC, independent of direction, could be related to progression of brain atrophy, which is associated with changes in clinical and cognitive functioning. Connectome stability enables fMRI data to be condensed into a proxy as a cross-sectional and longitudnal individual imaging marker.

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