Increased QT Variability Index as a Marker for a Cardiac Autonomic Dysregulation in Schizophrenia

Schizophrenia as severe mental disorder is characterized by a disintegration of the process of thinking and of emotional responsiveness whereas the underlying mechanisms of schizophrenia are complex and still discussed. The objective of this study is to find out if patients with schizophrenia and their healthy first-degree relatives have abnormal autonomic nervous system (ANS) activity by measuring cardiac indices as QT variability index (QTVI). Moreover, it is useful to study if ANS dysfunction could play an important role in schizophrenia and if abnormal functioning could be retrieved by patients' healthy first degree relatives. Also, a parallel experiment monitored QTVI in healthy controls before, during and after a new complex stress test named Mannheim Multicomponent Stress Test (MMST). As QT variability analysis results were not significantly different during MMST versus normal state, we concluded that short-term stress has no fundamental impact on ECG morphology in healthy subjects. However, patients with schizophrenia revealed an increased QTVI that indicates structural changes of ECG morphology in those patients. These findings were obviously independent from the findings regarding to healthy subjects under stress and healthy subjects (basic measurement of 30min).