title: Heart Rate Spectra Confirm the Presence of Autonomic Dysfunction in Dementia Patients.
abstract: Recent data suggest autonomic dysfunction in patients suffering dementia. This study evaluated autonomic modulation in dementia patients with and without autonomic involvement, employing ECG spectral analysis in the time-frequency domain (wavelet transform) in supine resting and head-up tilt (HUT) position. Thirty-six patients were prospectively evaluated at the Department of Neurology and Psychiatry, General Hospital of the City of Linz, between 2009 and 2014. A standard cardiovascular autonomic test series (Ewing battery) was performed to screen for autonomic dysfunction. The Ewing battery diagnoses were used as reference standard and compared to the diagnostic results obtained by spectral analysis (time-frequency domain) of ECG recordings. Based on the Ewing battery results, 14 patients suffered autonomic dysfunction, while 22 did not. Time frequency domain was accessed by using the continuous wavelet transformation (CWT) with an analytical Morlet mother wavelet in supine resting and HUT position. Within each cohort the modification of spectral components from supine resting to HUT was analyzed reflecting the autonomic modulation. For patients without autonomic dysfunction, a significant increase of autonomic modulation was detected by wavelet transformed ECG recordings (8%, p < 0.05; low frequency content) during HUT compared to supine resting. There was no significant modulation between HUT and supine resting in patients suffering autonomic dysfunction. In dementia patients suffering autonomic dysfunction, CWT identified blunted autonomic regulation only by analysis of ECG recordings without the need to assess other biosignals or tests depending on the patient's cooperation. Further studies are needed to evaluate whether CWT is a suitable method to support the standard Ewing battery in demented patients.
authors: Department of Neurology 2, Kepler University Hospital, Med Campus III., Linz, Austria.
authors: Walter
authors: W
authors: Struhal
authors: Department of Biomedical Engineering, Kepler University Hospital, Med Campus III., Linz, Austria.|Institute of Signal Processing, Johannes Kepler University Linz, Linz, Austria.
authors: Christoph
authors: C
authors: Mahringer
authors: Private Practice, Vienna, Austria.
authors: Heinz
authors: H
authors: Lahrmann
authors: Department of Anesthesiology and Critical Care Medicine, Kepler University Hospital, Med Campus III., Linz, Austria.
authors: Christoph
authors: C
authors: Mörtl
authors: Department of Biomedical Engineering, Kepler University Hospital, Med Campus III., Linz, Austria.
authors: Peter
authors: P
authors: Buhl
authors: Institute of Signal Processing, Johannes Kepler University Linz, Linz, Austria.
authors: Mario
authors: M
authors: Huemer
authors: Department of Neurology 2, Kepler University Hospital, Med Campus III., Linz, Austria.
authors: Gerhard
authors: G
authors: Ransmayr
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001342:Autonomic Nervous System Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018667:Tilt-Table Test / Q000379:methods*; D014636:Valsalva Maneuver / Q000502:physiology*
keywords: Alzheimer’s disease; autonomic nervous system; continuous wavelet 
  transformation; frontotemporal dementia; spectral analysis