ABSTRACT
Neurocardiac dysregulation has been reported in schizophrenia. Indices of heart rate variability (HRV) are useful in assessing the status of cardiac autonomic regulation. We explored within-subject changes in HRV indices in acutely ill patients with schizophrenia treated with risperidone. Sixteen medication-naïve or medication-free patients with DSM-IV schizophrenia completed electrocardiogram (ECG) assessments at baseline and after six weeks of treatment with risperidone. Indices of HRV were extracted from 5-min resting ECG recordings and compared to those obtained from control subjects matched for age and gender. Psychiatric and drug-induced extrapyramidal symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS) and the Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). In comparison with matched controls, patients with acute schizophrenia showed lower values of time-domain measures, lower high-frequency power (HF) and a higher ratio of low to high frequency (LF/HF). In the within-subject analyses, a significant decrease in LF/HF was associated with risperidone treatment. In addition, LF/HF, which initially co-clustered with clinical variables, congregated with other HRV measures after the six-week risperidone treatment. These results indicate that, in the therapeutic process, risperidone treatment may exert a beneficial influence on the sympathovagal imbalance in acute schizophrenia.
Subject(s)
Heart Rate/drug effects , Risperidone/therapeutic use , Schizophrenia/drug therapy , Sympathetic Nervous System/drug effects , Adult , Analysis of Variance , Antipsychotic Agents/therapeutic use , Cluster Analysis , Electrocardiography , Female , Heart Rate/physiology , Humans , Male , Middle Aged , Schizophrenia/physiopathology , Treatment OutcomeABSTRACT
The cardiac autonomic dysfunction has been reported in patients with schizophrenia. Heart rate variability (HRV) provides non-invasive indices of cardiac autonomic modulation. This study examined whether patients with schizophrenia may show a distinctive pattern of HRV compared to healthy controls. Nine measures of time, frequency and complexity domains were extracted from 5-min resting evaluation of HRV in 30 unmedicated patients with schizophrenia and 30 age- and gender-matched controls. In addition to inferential statistics, a hierarchical clustering (HC) was used to examine difference in the interrelationships among HRV measures between the two groups. Multivariate analysis of variance revealed a significant group effect. Significantly lower sample entropy (SampEn) and a trend towards a higher ratio of low- to high frequency (LF/HF) were observed in the schizophrenia group. In the results of HC using Ward's method, SampEn co-clustered with LF/HF ratio in patients with schizophrenia compared to the separation of LF/HF ratio in healthy controls. In concert with decreased parasympathetic activity, low complexity of heart rate dynamics may reduce adaptability of cardiovascular system to changes in internal or external environment, thus increasing the risk of cardiovascular events. Diverse HRV measures combined in a multivariate fashion appear to be useful in understanding the pattern of neurocardiac modulation in patients with schizophrenia.
