Cardiovascular and cardiorespiratory coupling in unmedicated schizophrenic patients in comparison to healthy subjects

Schizophrenia is associated with a cardiac autonomic dysregulation which is characterized by a decreased vagal modulation. Nevertheless, there are less information about the interrelationships of the cardiovascular and respiratory systems in schizophrenia. The aim of this study was to characterize short-term nonlinear cardiovascular and cardiorespiratory couplings in schizophrenia applying joint symbolic dynamics (JSD) analysis for an improved understanding of physiological processes of autonomic regulation in schizophrenia. We investigated 57 patients with schizophrenia (SZO) and 57 age-gender matched healthy controls (CON) for cardiovascular (N=37) and cardiorespiratory (N=20) coupling analysis. The results from cardiovascular coupling analysis demonstrated significantly decreased nonlinear bivariate word type combinations in SZO in comparison to CON (p<;0.01) as a sign of an impaired baroreflex mediated cardiovascular regulation. Analysis of cardiorespiratory coupling revealed a significant restricted respiratory variability (respiratory sinus arrhythmia) and a decreased cardiorespiratory coupling in SZO in comparison to CON and might be interpreted as a suppression of higher respiratory brainstem centers. In conclusion, we found an impaired and altered cardiovascular and cardiorespiratory coupling in unmedicated schizophrenic patients indicating a vagal withdrawal of autonomic modulation and an assumed suppression of higher regulatory centers of the brain stem in those patients.