title: Non-rapid eye movement sleep instability in mild cognitive impairment: a pilot study.
abstract: OBJECTIVE
  Polysomnographic (PSG) studies in mild cognitive impairment (MCI) are not conclusive and are limited only to conventional sleep parameters. The aim of our study was to evaluate sleep architecture and cyclic alternating pattern (CAP) parameters in subjects with MCI, and to assess their eventual correlation with cognition.
  
  
  METHODS
  Eleven subjects with MCI (mean age 68.5 ± 7.0 years), 11 patients with mild probable Alzheimer's disease (AD; mean age 72.7 ± 5.9 years), referred to the Outpatient Cognitive Disorders Clinic, and 11 cognitively intact healthy elderly individuals (mean age 69.2 ± 12.6 years) underwent ambulatory PSG for the evaluation of nocturnal sleep architecture and CAP parameters.
  
  
  RESULTS
  Rapid eye movement sleep, CAP rate, and CAP slow components (A1 index) were decreased in MCI subjects and to a greater extent in AD patients, compared to cognitively intact controls. AD showed also decreased slow wave sleep (SWS) relative to healthy elderly individuals. MCI nappers showed decreased nocturnal SWS and A1 subtypes compared to non-nappers. Several correlations between sleep variables and neuropsychological tests were found.
  
  
  CONCLUSIONS
  MCI and AD subjects showed a decreased sleep instability correlated with their cognitive decline. Such a decrease may be considered as a potential biomarker of underlying neurodegeneration.
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy. Electronic address: m.maestri@ao-pisa.toscana.it.
authors: Michelangelo
authors: M
authors: Maestri
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors: Luca
authors: L
authors: Carnicelli
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors: Gloria
authors: G
authors: Tognoni
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors: Elisa
authors: E
authors: Di Coscio
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors: Filippo Sean
authors: FS
authors: Giorgi
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors: Leda
authors: L
authors: Volpi
authors: Sleep Study Unit, Eginition Hospital, University of Athens Medical School, Athens, Greece.
authors: Nicholas-Tiberio
authors: NT
authors: Economou
authors: Sleep Study Unit, Eginition Hospital, University of Athens Medical School, Athens, Greece.
authors: Periklis
authors: P
authors: Ktonas
authors: Department of Neurology IC, Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy.
authors: Raffaele
authors: R
authors: Ferri
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors: Ubaldo
authors: U
authors: Bonuccelli
authors: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors: Enrica
authors: E
authors: Bonanni
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications*; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010865:Pilot Projects; D017286:Polysomnography; D012893:Sleep Wake Disorders / Q000523:psychology*; D012895:Sleep, REM / Q000502:physiology*
keywords: Alzheimer's disease; Cyclic alternating pattern; Mild cognitive impairment; NREM sleep instability; Nap; Neurodegeneration