Objective Altered cardiac autonomic function has been proposed in schizophrenia, but the results are mixed. Therefore, analyses with larger sample sizes and better methodology are needed. Methods To examine whether acute schizophrenia is associated with cardiac autonomic dysfunction, 314 unmedicated patients with acute schizophrenia and 409 healthy volunteers, aged 18-65 years, were recruited for a case-control analysis. The severity of schizophrenia symptoms was assessed with the Positive and Negative Syndrome Scale. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV) parameters during the supine-standing-supine test. Frequency-domain indices of HRV were obtained. Results Unmedicated patients with acute schizophrenia consistently exhibited reduced mean RR interval and HRV levels in a supine rest and standing position compared with healthy volunteers. The severity of psychopathology, in particular positive symptoms, was negatively correlated with cardiac vagal control. Conclusion These data suggest that acute schizophrenia is accompanied by cardiac autonomic dysregulation. In view of the higher risk for cardiac complications in these patients, one might also consider the antipsychotic treatment in favour of improving cardiac autonomic modulation. Further studies using larger patient groups and controlled therapeutics may better understand the influence of antipsychotic treatment on cardiac autonomic regulation in schizophrenia.
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