title: Autonomic dysfunction in mild cognitive impairment: evidence from power spectral analysis of heart rate variability in a cross-sectional case-control study.
abstract: BACKGROUND
  Mild cognitive impairment (MCI) is set to become a major health problem with the exponential ageing of the world's population. The association between MCI and autonomic dysfunction, supported by indirect evidence and rich with clinical implications in terms of progression to dementia and increased risk of mortality and falls, has never been specifically demonstrated.
  
  
  OBJECTIVE
  To conduct a comprehensive assessment of autonomic function in subjects with MCI by means of power spectral analysis (PSA) of heart rate variability (HRV) at rest and during provocative manoeuvres.
  
  
  METHODS
  This cross-sectional study involved 80 older outpatients (aged ≥ 65) consecutively referred to a geriatric unit and diagnosed with MCI or normal cognition (controls) based on neuropsychological testing. PSA was performed on 5-minute electrocardiographic recordings under three conditions--supine rest with free breathing (baseline), supine rest with paced breathing at 12 breaths/minute (parasympathetic stimulation), and active standing (orthosympathetic stimulation)--with particular focus on the changes from baseline to stimulation of indices of sympathovagal balance: normalized low frequency (LFn) and high frequency (HFn) powers and the LF/HF ratio. Blood pressure (BP) was measured at baseline and during standing. Given its exploratory nature in a clinical population the study included subjects on medications with a potential to affect HRV.
  
  
  RESULTS
  There were no significant differences in HRV indices between the two groups at baseline. MCI subjects exhibited smaller physiological changes in all three HRV indices during active standing, consistently with a dysfunction of the orthosympathetic system. Systolic BP after 10 minutes of standing was lower in MCI subjects, suggesting dysautonomia-related orthostatic BP dysregulation.
  
  
  CONCLUSIONS
  Our study is novel in providing evidence of autonomic dysfunction in MCI. This is associated with orthostatic BP dysregulation and the ongoing follow-up of the study population will determine its prognostic relevance as a predictor of adverse health outcomes.
authors.affiliation: Geriatric Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Nicolini
authors.affiliation: Cardiovascular Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Michele M
authors.initials: MM
authors.lastname: Ciulla
authors.affiliation: Department of Cardiology, Ospedale San Luca, Istituto Auxologico Italiano IRCCS, Milan, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Malfatto
authors.affiliation: Geriatric Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Abbate
authors.affiliation: Geriatric Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Mari
authors.affiliation: Geriatric Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Paolo D
authors.initials: PD
authors.lastname: Rossi
authors.affiliation: Geriatric Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Pettenuzzo
authors.affiliation: Cardiovascular Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Magrini
authors.affiliation: Epidemiology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Consonni
authors.affiliation: Cardiovascular Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Department of Clinical and Community Sciences, University of Milan, Milan, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Lombardi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D003710:Demography; D004562:Electrocardiography; D005260:Female; D005851:Geriatric Nursing; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests