The Cardiorespiratory Network in Healthy First-Degree Relatives of Schizophrenic Patients.

Steffen Schulz,Jens Haueisen,Karl-Jürgen Bär,Andreas Voss

doi:10.3389/fnins.2020.00617

Steffen Schulz, Jens Haueisen + Show 2 more

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https://doi.org/10.3389/fnins.2020.00617

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Abstract

Impaired heart rate- and respiratory regulatory processes as a sign of an autonomic dysfunction seems to be obviously present in patients suffering from schizophrenia. Since the linear and non-linear couplings within the cardiorespiratory system with respiration as an important homeostatic control mechanism are only partially investigated so far for those subjects, we aimed to characterize instantaneous cardiorespiratory couplings by quantifying the casual interaction between heart rate (HR) and respiration (RESP). Therefore, we investigated causal linear and non-linear cardiorespiratory couplings of 23 patients suffering from schizophrenia (SZO), 20 healthy first-degree relatives (REL) and 23 healthy subjects, who were age-gender matched (CON). From all participants’ heart rate (HR) and respirations (respiratory frequency, RESP) were investigated for 30 min under resting conditions. The results revealed highly significant increased HR, reduced HR variability, increased respiration rates and impaired cardiorespiratory couplings in SZO in comparison to CON. SZO were revealed bidirectional couplings, with respiration as the driver (RESP → HR), and with weaker linear and non-linear coupling strengths when RESP influencing HR (RESP → HR) and with stronger linear and non-linear coupling strengths when HR influencing RESP (HR → RESP). For REL we found only significant increased HR and only slightly reduced cardiorespiratory couplings compared to CON. These findings clearly pointing to an underlying disease-inherent genetic component of the cardiac system for SZO and REL, and those respiratory alterations are only clearly present in SZO seem to be connected to their mental emotional states.

Highlights

Schizophrenia represents a mental disorder along with increased cardiovascular mortality rate, shorter life expectancy, higher risk of developing cardiovascular disease (CVD) in proportion to the general population (Hennekens et al, 2005; McGrath et al, 2008; Laursen et al, 2014)
We found highly significant increased heart rate (HR), reduced heart rate variability (HRV), higher breathing frequency (BF), and impaired cardiorespiratory couplings for schizophrenic patients compared to healthy control subjects
For the healthy first-degree relatives we found only significant increased HR and impaired respiratory sinus arrhythmia (RSA) compared to healthy subjects (Figures 2, 3)

Summary

Introduction

Schizophrenia represents a mental disorder along with increased cardiovascular mortality rate, shorter life expectancy, higher risk of developing cardiovascular disease (CVD) in proportion to the general population (Hennekens et al, 2005; McGrath et al, 2008; Laursen et al, 2014). Different studies suggested as a major contributing factor the unbalanced sympathovagal balance for schizophrenic patients, as well as for their healthy first-degree relatives (ValkonenKorhonen et al, 2003; Bär et al, 2005, 2007; Chang et al, 2009; Schulz et al, 2013c). Network Physiology quantifies healthy and diseased states investigating the coupling between systems and subsystems by determining structural, dynamical and regulatory changes. These new concepts allow getting a better understanding of the complexity of physiological as well as pathophysiological processes in health and disease by linking genetic and subcellular levels with intercellular coupling pathways between integrated systems and subsystems (Ivanov et al, 2016)

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