Relationship between heart rate variability and the severity of psychotic symptoms in schizophrenia.

Objective: The relationship between autonomic neurocardiac function and schizophrenia remains elusive. This study investigated the relationship between the heart rate variability (HRV) parameters and the severity of psychotic symptoms in schizophrenic patients. Methods: Twenty-one patients receiving risperidone monotherapy and 21 matched normal control subjects were evaluated for HRV analysis. The severity of schizophrenic symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS) and a five-factor model of the PANSS was used. Results: The value of the ratio of low-to-high frequency spectral power was significantly higher in the patient group. The patient group also showed a significantly lower value of approximate entropy. After controlling the dosage of risperidone, the PANSS total score had significant negative correlations with the standard deviation of all RR intervals (SDNN) and the square root of the mean squared differences of successive normal sinus intervals (RMSSD). With respect to the PANSS factors, the score of the PANSS cognitive/disorganisation factor had significant negative correlations with SDNN and RMSSD. Conclusion: These results provide some evidence that the severity of psychotic symptoms, especially cognitive/disorganisation symptom dimensions, may be associated with reduced HRV, suggesting a potential involvement of neuroautonomic dysfunction in the pathophysiology of specific symptoms of schizophrenia. Jong-Hoon Kim1, Jun-Hyung Ann2, Jinyoung Lee1