Contributions
Abstract: P1158
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Neuropsychology
Introduction: The underlying mechanisms of cognitive impairment in multiple sclerosis (MS) are complex and incompletely understood. Previous studies have demonstrated a potential role for disrupted brain network organisation in understanding cognitive impairment in MS. However, it remains unclear which organisational network measures are the best indicators of cognitive impairment in MS, and how these measures relate to structural brain measures.
Objectives: To determine the relation between functional brain network organisation and cognitive impairment in MS patients, and to identify the importance of network organisation relative to structural brain measures.
Methods: A neuropsychological battery was administered in 145 MS patients. Magnetoencephalography (MEG) recordings were projected onto the automated anatomical labelling atlas using a beamforming approach. Functional connectivity between brain regions was calculated with the phase lag index (PLI). Brain network organisation was investigated using frequency-specific network properties of the Minimum Spanning Tree (MST; i.e. the backbone of the functional brain network). Correlational analyses and backward regression models were performed to relate these network measures to cognitive impairment, and to explore their unique effects beyond grey matter (GM) atrophy and white matter (WM) lesions (measured with MRI).
Results: Cognitive impairment was related to multiple MST network properties (p< .008), including a lower tree hierarchy in the higher alpha, beta and gamma band, and a lower leaf fraction in the lower alpha and beta band. A lower tree hierarchy in the higher alpha band was the best MST predictor of cognitive impairment (R2 final model=.14). This MST measure remained an independent predictor of cognition when cortical GM atrophy and WM lesion volume were added to the model, but not when deep GM atrophy was added.
Conclusions: A loss of functional brain network hierarchy related to worse cognitive performance in MS patients. These network changes seemed relatively independent of cortical GM atrophy and WM lesion volume in their relation to cognition. Deep GM atrophy did affect the relation between network organisation and cognition, which may indicate that deep GM atrophy and cortical network changes are part of the same mechanism underlying cognitive impairment. These findings add important insights into the interplay between function and structure in relation to cognitive function in MS.
Disclosure: I.M. Nauta is supported by the Dutch MS Research Foundation, grant nr. 15-911. S.D. Kulik reports no disclosures. L. Breedt reports no disclosures. A.J.C. Eijlers is supported by the Dutch MS Research Foundation, grant nr. 13-358e. E.M.M. Strijbis reports no disclosures. P. Tewarie has received funding for travel from Novartis. A. Hillebrand serves as an editorial board member of Scientific Reports and Plos One. C.J. Stam reports no disclosures. L. Douw receives research support from Society in Science (Branco Weiss Fellowship). J.J.G. Geurts is an editor of Multiple Sclerosis Journal. He serves on the editorial boards of Neurology and Frontiers of Neurology and is president of the Netherlands organization for health research and innovation. He has served as a consultant for Merck-Serono, Biogen, Novartis, Genzyme and Teva Pharmaceuticals. B.M.J. Uitdehaag has received personal compensation for consulting from Biogen Idec, Genzyme, Merck Serono, Novartis, Roche and TEVA. B.A. de Jong has received speaker and consulting fees from Merck-Serono, Biogen, TEVA, Genzyme and Novartis. M.M. Schoonheim serves as an editorial board member of Frontiers in Neurology, received research support from the Dutch MS Research Foundation and consulting or speaking fees from ExceMed, Genzyme, Novartis, and Biogen.
Abstract: P1158
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Neuropsychology
Introduction: The underlying mechanisms of cognitive impairment in multiple sclerosis (MS) are complex and incompletely understood. Previous studies have demonstrated a potential role for disrupted brain network organisation in understanding cognitive impairment in MS. However, it remains unclear which organisational network measures are the best indicators of cognitive impairment in MS, and how these measures relate to structural brain measures.
Objectives: To determine the relation between functional brain network organisation and cognitive impairment in MS patients, and to identify the importance of network organisation relative to structural brain measures.
Methods: A neuropsychological battery was administered in 145 MS patients. Magnetoencephalography (MEG) recordings were projected onto the automated anatomical labelling atlas using a beamforming approach. Functional connectivity between brain regions was calculated with the phase lag index (PLI). Brain network organisation was investigated using frequency-specific network properties of the Minimum Spanning Tree (MST; i.e. the backbone of the functional brain network). Correlational analyses and backward regression models were performed to relate these network measures to cognitive impairment, and to explore their unique effects beyond grey matter (GM) atrophy and white matter (WM) lesions (measured with MRI).
Results: Cognitive impairment was related to multiple MST network properties (p< .008), including a lower tree hierarchy in the higher alpha, beta and gamma band, and a lower leaf fraction in the lower alpha and beta band. A lower tree hierarchy in the higher alpha band was the best MST predictor of cognitive impairment (R2 final model=.14). This MST measure remained an independent predictor of cognition when cortical GM atrophy and WM lesion volume were added to the model, but not when deep GM atrophy was added.
Conclusions: A loss of functional brain network hierarchy related to worse cognitive performance in MS patients. These network changes seemed relatively independent of cortical GM atrophy and WM lesion volume in their relation to cognition. Deep GM atrophy did affect the relation between network organisation and cognition, which may indicate that deep GM atrophy and cortical network changes are part of the same mechanism underlying cognitive impairment. These findings add important insights into the interplay between function and structure in relation to cognitive function in MS.
Disclosure: I.M. Nauta is supported by the Dutch MS Research Foundation, grant nr. 15-911. S.D. Kulik reports no disclosures. L. Breedt reports no disclosures. A.J.C. Eijlers is supported by the Dutch MS Research Foundation, grant nr. 13-358e. E.M.M. Strijbis reports no disclosures. P. Tewarie has received funding for travel from Novartis. A. Hillebrand serves as an editorial board member of Scientific Reports and Plos One. C.J. Stam reports no disclosures. L. Douw receives research support from Society in Science (Branco Weiss Fellowship). J.J.G. Geurts is an editor of Multiple Sclerosis Journal. He serves on the editorial boards of Neurology and Frontiers of Neurology and is president of the Netherlands organization for health research and innovation. He has served as a consultant for Merck-Serono, Biogen, Novartis, Genzyme and Teva Pharmaceuticals. B.M.J. Uitdehaag has received personal compensation for consulting from Biogen Idec, Genzyme, Merck Serono, Novartis, Roche and TEVA. B.A. de Jong has received speaker and consulting fees from Merck-Serono, Biogen, TEVA, Genzyme and Novartis. M.M. Schoonheim serves as an editorial board member of Frontiers in Neurology, received research support from the Dutch MS Research Foundation and consulting or speaking fees from ExceMed, Genzyme, Novartis, and Biogen.