Chang JS; Yoo CS;
Yi SH; Hong KH; Oh HS; Hwang JY; Kim SG; Ahn YM; Kim YS
Department of Neuropsychiatry, Seoul National University Bundang
Hospital, 300 Gumi-Dong, Bundang-Gu, Seongnam-Si, Gyeonggi-Do 463-707,
Republic of Korea.
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.