title: Differences in EEG delta frequency characteristics and patterns in slow-wave sleep between dementia patients and controls:  a pilot study.
abstract: OBJECTIVE
  To evaluate the modifications of EEG activity during slow-wave sleep in patients with dementia compared with healthy elderly subjects, using spectral analysis and period-amplitude analysis.
  
  
  METHODS
  Five patients with dementia and 5 elderly control subjects underwent night polysomnographic recordings. For each of the first three nonrapid eye movement-rapid eye movement sleep cycles, a well-defined slow-wave sleep portion was chosen. The delta frequency band (0.4-3.6 Hz) in these portions was analyzed with both spectral analysis and period-amplitude analysis.
  
  
  RESULTS
  Spectral analysis showed an increase in the delta band power in the dementia group, with a decrease across the night observed only in the control group. For the dementia group, period-amplitude analysis showed a decrease in well-defined delta waves of frequency lower than 1.6 Hz and an increase in such waves of frequency higher than 2 Hz, in incidence and amplitude.
  
  
  CONCLUSIONS
  Our study showed (1) a loss of the dynamics of delta band power across the night sleep, in dementia, and (2) a different distribution of delta waves during slow-wave sleep in dementia compared with control subjects. This kind of computer-based analysis can highlight the presence of a pathologic delta activity during slow-wave sleep in dementia and may support the hypothesis of a dynamic interaction between sleep alteration and cognitive decline.
authors.affiliation: Department of Neurosciences, University of Pisa, Pisa, Italy. e.bonanni@med.unipi.it
authors.forename: Enrica
authors.initials: E
authors.lastname: Bonanni
authors.forename: Elisa
authors.initials: E
authors.lastname: Di Coscio
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Maestri
authors.forename: Luca
authors.initials: L
authors.lastname: Carnicelli
authors.forename: Hara
authors.initials: H
authors.lastname: Tsekou
authors.forename: Nicholas Tiberio
authors.initials: NT
authors.lastname: Economou
authors.forename: Thomas
authors.initials: T
authors.lastname: Paparrigopoulos
authors.forename: Anastasios
authors.initials: A
authors.lastname: Bonakis
authors.forename: Sokratis G
authors.initials: SG
authors.lastname: Papageorgiou
authors.forename: Dimitris
authors.initials: D
authors.lastname: Vassilopoulos
authors.forename: Constantin R
authors.initials: CR
authors.lastname: Soldatos
authors.forename: Luigi
authors.initials: L
authors.lastname: Murri
authors.forename: Periklis Y
authors.initials: PY
authors.lastname: Ktonas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000503:physiopathology*; D003700:Delta Rhythm / Q000502:physiology*; D003704:Dementia / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*