title: Brain network connectivity assessed using graph theory in frontotemporal dementia.
abstract: OBJECTIVE
  To investigate whether brain functional network connectivity is disrupted in patients with the behavioral variant of frontotemporal dementia (bvFTD).
  
  
  METHODS
  Graph theoretical analysis was applied to resting state functional MRI data from 18 patients with probable bvFTD and 50 healthy individuals. Functional connectivity between 90 cortical and subcortical brain regions was estimated using bivariate correlation analysis and thresholded to construct a set of undirected graphs. Correlations between network properties and cognitive variables were tested.
  
  
  RESULTS
  Global topologic organization of the functional brain network in bvFTD was significantly disrupted as indicated by reduced mean network degree, clustering coefficient, and global efficiency and increased characteristic path length and assortativity relative to normal subjects. Compared to controls, bvFTD data showed retention of major "hub" regions in the medial parietal, temporal, and occipital lobes, but cortical hubs were not noted in the frontal lobes. Medial and dorsal frontal regions, left caudate nucleus, left insular cortices, and some regions of the temporal, parietal, and occipital lobes showed decreased nodal centrality. BvFTD patients showed the greatest decrease in inter-regional connectivity between the frontal and occipital regions, and the insular cortices and occipital, temporal, subcortical, and frontal regions. In bvFTD, altered global network properties correlated with executive dysfunction.
  
  
  CONCLUSIONS
  Global and local functional networks are altered in bvFTD, suggesting a loss of efficiency in information exchange between both distant and close brain areas. Altered brain regions are located in structures that are closely associated with neuropathologic changes in bvFTD. Aberrant topology of the functional brain networks in bvFTD appears to underlie cognitive deficits in these patients.
authors.affiliation: Neuroimaging Research Unit, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Agosta
authors.forename: Sara
authors.initials: S
authors.lastname: Sala
authors.forename: Paola
authors.initials: P
authors.lastname: Valsasina
authors.forename: Alessandro
authors.initials: A
authors.lastname: Meani
authors.forename: Elisa
authors.initials: E
authors.lastname: Canu
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magnani
authors.forename: Stefano F
authors.initials: SF
authors.lastname: Cappa
authors.forename: Elisa
authors.initials: E
authors.lastname: Scola
authors.forename: Piero
authors.initials: P
authors.lastname: Quatto
authors.forename: Mark A
authors.initials: MA
authors.lastname: Horsfield
authors.forename: Andrea
authors.initials: A
authors.lastname: Falini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
authors.forename: Massimo
authors.initials: M
authors.lastname: Filippi
mesh_terms: D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D056344:Executive Function / Q000502:physiology; D005260:Female; D057180:Frontotemporal Dementia / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009415:Nerve Net / Q000503:physiopathology*; D016571:Neural Networks, Computer; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales