title: Functional Connectivity Changes in Resting-State EEG as Potential Biomarker for Amyotrophic Lateral Sclerosis.
abstract: BACKGROUND
  Amyotrophic Lateral Sclerosis (ALS) is heterogeneous and overlaps with frontotemporal dementia. Spectral EEG can predict damage in structural and functional networks in frontotemporal dementia but has never been applied to ALS.
  
  
  METHODS
  18 incident ALS patients with normal cognition and 17 age matched controls underwent 128 channel EEG and neuropsychology assessment. The EEG data was analyzed using FieldTrip software in MATLAB to calculate simple connectivity measures and scalp network measures. sLORETA was used in nodal analysis for source localization and same methods were applied as above to calculate nodal network measures. Graph theory measures were used to assess network integrity.
  
  
  RESULTS
  Cross spectral density in alpha band was higher in patients. In ALS patients, increased degree values of the network nodes was noted in the central and frontal regions in the theta band across seven of the different connectivity maps (p<0.0005). Among patients, clustering coefficient in alpha and gamma bands was increased in all regions of the scalp and connectivity were significantly increased (p=0.02). Nodal network showed increased assortativity in alpha band in the patients group. The Clustering Coefficient in Partial Directed Connectivity (PDC) showed significantly higher values for patients in alpha, beta, gamma, theta and delta frequencies (p=0.05).
  
  
  CONCLUSIONS
  There is increased connectivity in the fronto-central regions of the scalp and areas corresponding to Salience and Default Mode network in ALS, suggesting a pathologic disruption of neuronal networking in early disease states. Spectral EEG has potential utility as a biomarker in ALS.
authors.affiliation: School of Medicine, Trinity College Dublin, Dublin 2, Ireland; Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Parameswaran Mahadeva
authors.initials: PM
authors.lastname: Iyer
authors.affiliation: School of Engineering, Trinity College Dublin, Dublin 2, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Catriona
authors.initials: C
authors.lastname: Egan
authors.affiliation: Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Marta
authors.initials: M
authors.lastname: Pinto-Grau
authors.affiliation: Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Tom
authors.initials: T
authors.lastname: Burke
authors.affiliation: School of Medicine, Trinity College Dublin, Dublin 2, Ireland; Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Marwa
authors.initials: M
authors.lastname: Elamin
authors.affiliation: Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Bahman
authors.initials: B
authors.lastname: Nasseroleslami
authors.affiliation: Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Niall
authors.initials: N
authors.lastname: Pender
authors.affiliation: School of Engineering, Trinity College Dublin, Dublin 2, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Edmund C
authors.initials: EC
authors.lastname: Lalor
authors.affiliation: Academic Unit of Neurology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland.
authors.forename: Orla
authors.initials: O
authors.lastname: Hardiman
mesh_terms: D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000503:physiopathology*; D015415:Biomarkers; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D063132:Connectome / Q000379:methods; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways; D012372:ROC Curve
chemical_list: D015415:Biomarkers