Analyses of Heart Rate, Respiration and Cardiorespiratory Coupling in Patients with Schizophrenia

Steffen Schulz,Andreas Voss,Karl-Jürgen Bär

doi:10.3390/e17020483

Steffen Schulz, Andreas Voss + Show 1 more

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https://doi.org/10.3390/e17020483

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Journal: Entropy	Publication Date: Jan 23, 2015
Citations: 80	License type: CC BY 4.0

Affiliation: Carl Zeiss (Germany), Jena University Hospital

Abstract

Schizophrenia is a severe mental disorder associated with a significantly increased cardiovascular mortality rate. However, the underlying mechanisms leading to this cardiovascular disease (CVD) are not fully known. Therefore, the objective of this study was to characterize the cardiorespiratory influence by investigating heart rate, respiration and the causal strength and direction of cardiorespiratory coupling (CRC), based mainly on entropy measures. We investigated 23 non-medicated patients with schizophrenia (SZ), comparing them to 23 age- and gender-matched healthy controls (CO). A significantly reduced complexity was found for the heart rate and a significantly increased complexity in respiration and CRC in SZ patients when compared to corresponding measurements from CO (p < 0.001). CRC analyses revealed a clear coupling, with a driver-responder relationship from respiration to heart rate in SZ patients. Moreover, a slight driver-responder relationship from heart rate to respiration could be recognized. These findings lead to the assumption that SZ should be considered to be a high-risk group for CVD. We hypothesize that the varying cardiorespiratory regulation contributes to the increased risk for cardiac mortality. Therefore, regular monitoring of the cardiorespiratory status of SZ is suggested to identify autonomic regulation impairment at an early stage—to develop timely and effective treatment and intervention strategies.

Highlights

Schizophrenia is referred to as one of the most severe mental disorders in the world, and patients with this condition are associated with high cardiac mortality rates
We found a significantly increased heart rate, reduced heart rate variability, increased breathing rates and impaired cardiorespiratory coupling in patients with schizophrenia when compared to healthy subjects
We could demonstrate the following results using various univariate and bivariate entropy-based measures: heart rate variability was characterized by a reduced complexity level, respiratory variability was characterized by an increased complexity, and cardiorespiratory coupling was reduced in schizophrenic patients

Summary

Introduction

Schizophrenia is referred to as one of the most severe mental disorders in the world, and patients with this condition are associated with high cardiac mortality rates These patients have an approximately 15 to 20-year shorter life expectancy and a relatively high risk for attaining cardiovascular disease (CVD);. There is ample evidence that a dysfunction of the autonomic nervous system (ANS), determined by investigating heart rate variability (HRV), is obviously present in schizophrenia patients. These studies found a vagal withdrawal and a sympathetic predominance for these patients, as well as in part for their healthy first-degree relatives [6,7,8,9,10]

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