title: Two separable mechanisms are responsible for mental stress effects on high frequency heart rate variability: an intra-individual approach in a healthy and a diabetic sample.
abstract: Central withdrawal of parasympathetic cardiac control and increased respiratory frequency represent two important determinants of reduced respiratory-related heart rate variability (HRV). However, studies are missing to disentangle their relative contribution during mental stress. Healthy subjects (n=10) and type 2 diabetic patients (n=8), the latter with evidence of cardiac autonomic neuropathy, participated in this study. Using an intra-individual approach, high-frequency (hf) HRV was assessed for spontaneous (during rest and mental stress) and paced breathing (0.15, 0.2, 0.25, 0.3, 0.35, 0.4 and 0.45 Hz; randomized sequence). Mental stress was induced by a challenging reaction time task. Effects of respiratory frequency on hf HRV were individually predicted by paced breathing data. Mental stress decreased hf HRV (p<.001), and increased respiratory frequency (p=.01). Individual prediction of hf HRV by stress respiratory frequency resulted in lower values (p=.02) than observed during rest, indicating that respiratory stress effects were sufficient to reduce hf HRV. However, observed hf HRV values during stress were even lower (p<.001). These results indicate that hf HRV reductions during stress can only partly be explained by concomitant respiratory frequency changes. This effect is detectable in healthy subjects and in patients with evidence of diabetic cardiac autonomic neuropathy.
authors.affiliation: Department of Psychiatry and Psychotherapy, Charité University Medical School Berlin, Campus Benjamin Franklin, Eschenallee 3, 14050 Berlin, Germany. Electronic address: linn.kuehl@charite.de.
authors.forename: Linn K
authors.initials: LK
authors.lastname: Kuehl
authors.affiliation: Department of Psychiatry and Psychotherapy, Charité University Medical School Berlin, Campus Benjamin Franklin, Eschenallee 3, 14050 Berlin, Germany; Department of Clinical Psychophysiology, Institute of Psychobiology, University of Trier, Johanniterufer 15, 54290 Trier, Germany. Electronic address: christian.deuter@charite.de.
authors.forename: Christian E
authors.initials: CE
authors.lastname: Deuter
authors.affiliation: Department of Psychiatry and Psychotherapy, Charité University Medical School Berlin, Campus Benjamin Franklin, Eschenallee 3, 14050 Berlin, Germany. Electronic address: steffen.richter@charite.de.
authors.forename: Steffen
authors.initials: S
authors.lastname: Richter
authors.affiliation: Institute for Health and Behaviour, Research Unit INSIDE, University of Luxembourg, Route de Diekirch, L-7220 Walferdange, Luxembourg. Electronic address: andre.schulz@uni.lu.
authors.forename: André
authors.initials: A
authors.lastname: Schulz
authors.affiliation: University of Trier, Centre for Psychobiological and Psychosomatic Research, Department of Behavioral Medicine, St. Franziska Stift, Franziska-Puricelli-Str. 3, 55543 Bad Kreuznach, Germany. Electronic address: heinz.rueddel@gmx.de.
authors.forename: Heinz
authors.initials: H
authors.lastname: Rüddel
authors.affiliation: Department of Clinical Psychophysiology, Institute of Psychobiology, University of Trier, Johanniterufer 15, 54290 Trier, Germany. Electronic address: schaechi@uni-trier.de.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Schächinger
mesh_terms: D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012119:Respiration; D013315:Stress, Psychological / Q000503:physiopathology*
keywords: Diabetes mellitus; Heart rate variability; Respiratory frequency; Stress; Vagal withdrawal