| Backgroud:Sub-health is an intermediate state between health and illness. The characteristics of sub-health are lower vitality and sleep quality, physical and physiological disorder and the loss of the quality of life. About 17.8 to 60.5 percent people are suffering from sub-health, especially the young and middle-age officials. Since the cause and the symptoms of sub-health were so complicated, there was not yet an effective method to deal with it. In the last few years, recuperating sub-health according to the theory of constitution in Traditional Chinese Medicine had become more and more popular.Traditional Chinese Medicine (TCM) refers to an integrated, metastable and natural specialty of individuals in morphosis, physiological functions and psychological conditions, formed on the basis of innate and acquired endowments in the process of life. The diversity of genetic backgrounds and the complexity of acquired conditions make the constitution have apparent individual differences and exhibit polymorphism, so it is a pivotal method to classify similar symptoms into syndromes for individuals in the general population and provide new insights in the conditioning of sub-health.The constitution and its classification were first documented in the classic Chinese medical text Huangdi Neijing, which provided three axes on which personal constitution is classified:morphological and physical features, the yin-yang quadrant, and the five evolutive phases. Based on the tradition established by this text, subsequent Chinese scholar had put forward many different theory of the division of constitution. During the Eastern Han Dynasty, Zhang Zhongjing, the famous specialist in TCM, classified individual differences in human health according to the relationship between constitution and the occurrence, nature, development, and prognosis of disease. Thereafter, other specialists during the Tang, Jin, Yuan, Ming and Qing Dynasties described and classified individual differences from different viewpoints. Present constitutional theory of TCM was proposed by the late 1970s. However, there was no uniform standard for the determination until the nine-constitution scale, the constitution in Chinese medicine questionnaire (CCMQ), published as a bulletin in 2009 by the China Association for Traditional Chinese Medicine. The inconformity towards the classification of constitution prohibited the development and universal of constitutional research and had undesirable effect on the practical applications of constitutional theory.The nine constitutions consist of balance constitution, qi-deficiency, yang-deficiency, yin-deficiency, phlegm-wetness, wet-heat, blood-stasis, qi-depression and special diathesis type. The balance constitution represents an overall healthy state while others are abnormal constitutions. In general, an individual with the specific abnormal constitution will have an associated metabolism, a measured property or marker, and some general tendencies suggesting special behavior or biological and physiological characteristics. Most people diagnosed with abnormal constitution have the tendency to suffer sleep disturbance, functional gastrointestinal disorders, have bad psychic reaction such as anxiety or depression, or have the susceptibility of some specific kind of disease, which in turn have awful influence on their daily life. According to the constitutional theory, the abnormal constitutions could be adjusted and translated into the balance one, which provides an effective method with characteristics of traditional Chinese medicine for the improvement of sub-health condition.Based on the constitutional theory of TCM, many researchers attempted to adopt objective measures to explore the physiological phenomena, pathological mechanism and even the genetic features of the constitutions. It was reported that yin-deficiency was related to some extent with the disturbances in the hypothalamus-pituitary-adrenal axis, hypothalamus-pituitary-thyroid axis, cyclic nucleoside system and immune function. Besides, one study detecting the gene expression identified that 785 genes are up-regulated and 954 genes were down-regulated in yang-deficient constitution compared to balance constitution. All these findings gave further evidence for the scientific basis of constitutional classification and validated its accuracy and practicality to a certain degree.TCM constitution and autonomic nervous system (ANS) are closely related with each other. Previous studies have showed that emotional reaction and gastrointestinal activities are relevant to the regulation of ANS. Spectral HRV analysis has been regarded as a sensitive and noninvasive method of assessing the autonomic nervous activity, which demonstrates that the high frequency power (HF) reflects the parasympathetic (vagal) activity, whereas the low frequency power (LF) reflects sympathetic activity with a parasympathetic component. Therefore, the LF-to-HF ratio (LF/HF) was computed as measure of the sympathovagal balance. Since the history of the nine-constitutional scale is short, study adopting HRV indexes to explore the relationship between the abnormal constitutions and the autonomic nervous regulation has not been reported yet.As far as we know, the diagnosis of TCMC merely depends on subjective scale and is in the absence of some objective measurements. Even though a few studies had attempted to explore the objective methods of constitutional characterization, including pulse waves, tongue images or acoustic features, it is uncertain whether their results can be applied to the general population since those previous studies involved subjects with various diseases.Objective:This study is to identify the relationship between the constitution of Traditional Chinese Medicine and heart rate variability. Once the association between heart rate variability and TCMC is deciphered, there may be an effective objective measurement that can contribute to the estimation of TCMC.Methods:SubjectsA total of 265 participants were included into this study between November 2013 and June 2014. All the subjects were more than 18 years and able to give valid answers during the interview. Each questionnaire consisted of an information sheet that described the nature and purpose of the study, and explained that the subjects were voluntary. The respondents were assured that their responses would remain confidential.Subjects were screened and excluded if they had (1) current or past digestive, cardiovascular system diseases or drug use, alcohol abuse or excessive caffeine consumption, (2) any substance-induced, past or family psychiatric history, (3) an acute medical illness within 1 months of the start of the study.Determination of TCM constitutionThe constitution in Chinese medicine questionnaire (CCMQ) developed by Wang Qi in 2009 was applied to determine the TCM constitution. CCMQ was selected by the Chinese government to be part of the "National Standards of Public Health Service and is commonly used nationwide. It includes 60 items and 9 sub-scales of self-evaluation. Each question was answered by choosing one of the Five options from the scale, such as Never (1), Rarely (2), Sometimes (3), Often (4), and Always (5). The points of each sub-scale were summed up to determine the particular constitution for each person. Sub-scale summary score was standardized from 0 to 100 by using the formula as (Sum-Lowest score)/(Highest score-Lowest score) multiplied by 100.Subject with normal constitutional scores of more than 60 and the other certain abnormal constitutional scores of less than 40 can be identified as gentleness type, whereas they can be judged as one kind of abnormal constitution.Twenty-four-hour ECG monitoringStandard 12-chanel ambulatory electrocardiogram (Peng Yang Feng Ye medical equipment industry, Beijing, China) was applied to obtain continuous ECG data for 24 hours. Participants were asked to maintain their usual daily activities and to avoid smoking and drinking alcoholic beverages during testing. The ECG signals were automatically processed and analyzed by open-source HRV algorithms.HRV analysis is a method of evaluation of the neurohumor regulation of heart correlations between sympathetic and parasympathetic departments of vegetative nerve system. HRV parameters include SDANN (standard deviation of the averages of NN intervals in all 5 min segments of the entire recording), RMSSD (the square root of the mean of the sum of the squares of differences between adjacent NN intervals), SDNN (standard deviation of all NN intervals), VLF (very-low-frequency power,0.003-0.04 Hz), LF (low-frequency power,0.04-0.15 Hz), and HF (high-frequency power,0.15-0.40 Hz).Statistical analysisData processing and analysis were performed with SPSS Version 20.0 software. Chi-square test and independent-samples t-test were used to compare the demographic characteristics. Independent-samples t-test was used to compare heart rate and HRV parameters between balance constitution and the abnormal constitution. Partial correlation analysis was applied, controlling for age and BMI, to identify associations between HRV indices and the scores of the abnormal constitution. Paired-samples t-test was used to compare the HRV parameters of waking or sleeping state. Wilcoxon rank sum test was applied to compare the difference of HRV parameters between waking and sleeping state. A two-tailed p-value of less than 0.05 was considered to statistical significance for all comparisons.Results:1 A total of 265 participants including 118 males and 147 females were involved in this study. Among them,71 participants were in balance constitution,50 participants were in yang-deficiency constitution,68 participants were in yin-deficiency constitution,60 participants were in qi-deficiency constitution,34 participants were in qi-depression constitution,48 participants were in phlegm-wetness constitution,59 participants were in heat-wet constitution,19 participants were in blood-stasis constitution and the other 19 were in special diathesis constitution. The results showed no significant difference in terms of sex, age, height, weight and BMI when compared one specific constitution group with the balance constitution group (P>0.05).2 Decreased SDANN was found in abnormal constitution group when compared with the balance constitution (P＜0.05), illustrating that the sympathetic activity was decreased in individuals with abnormal constitutions.Individuals with different constitutions had different change of their heart rate variability. SDANN (P＜0.05), VLF (P<0.05) and LF/HF (P＜0.05) decreased but HF (P<0.05) increased in individuals with yang-deficiency when compared with the balance group, illustrating that decreased sympathovagal balance was found in yang-deficiency individuals. Individuals with qi-deficiency had decreased SDANN and SDNN (P＜0.05), showing that their sympathetic activity decreased. Phlegm-wet individuals had decreased VLF (P＜0.05) and blood-stasis individuals had decreased both in SDANN (P＜0.05) and SDNN (P＜0.05).3 We could see from the partial correlation that the value of VLF (r=-0.633, P＜0.05) and LF/HF (r=-0.457, P＜0.05) were significantly and negatively correlated with the scores of yang-deficiency constitution. LF/HF (r=-0.150, P＜0.05) was significantly and positively correlated with the scores of qi-deficiency constitution. SDANN was significantly and negatively with the scores of both phlegm-wet constitution (r=-0.127, P＆0.05) and blood-stasis constitution (r=-0.754, P＜0.01).4 For the individuals with balance constitution, LF and HF in sleep state was lower than that in waking state (.P＜0.05). However, for the individuals with the abnormal constitutions, only LF in sleep state was significantly lower than that in waking state (P＜0.05) and the change was reduced than that in balance group. In terms of each abnormal constitution, only qi-deficiency individuals had significant decrease LF (P＜0.05). There were so significant difference in the HRV parameters between the sleep state and waking state among other abnormal constitution individuals.5 In terms of the difference in the awaked HRV parameters, we could see that decreased VLF was found in yang-deficiency individuals (P＜0.05) and phlegm-wet individuals (P＜0.05) when compared with the balance group. What’s more, in terms of the difference in the asleep HRV parameters, we could see that LF (P＜0.05) and HF (P＜0.05) was decreased in yang-deficiency individuals. There were no significant difference in HRV parameters were found in the comparison between the other one specific abnormal constitution and the balance constitution.6 In terms of the difference of the HRV parameters in waking and sleep (day and night) state, we could see that the difference was minished in the abnormal constitution group than the balance group (P<0.05). Difference of both LF (P<0.05) and HF (P<0.05) between day and night were minished in yang-deficiency individuals and difference of LF was minished in special diathesis constitution group.Conclusion:1 Compared with balance constitution group, individuals with abnormal constitutions had decreased sympathetic activity to some extent. Individuals with different abnormal constitutions had different change in their autonomic nervous activity when compared with the balanced constitution group. Yang-deficiency individuals had decreased parasympathetic activity, sympathovagal balance and increased sympathetic activity. Individuals with qi-deficiency and blood-stasis had decreased sympathetic activity and the influence of the autonomic tone on the heart rate was also reduced. Individuals with phlegm-wet had decreased sympathetic activity but there was no significant change in their parasympathetic activity.2 There was some correlation between heart rate variability and the scores of the abnormal constitutions. The sympathovagal balance was significantly and negatively correlated with the scores of yang-deficiency, indicating that the sympathovagal imbalance became severer as the yang-deficiency degree increased. The sympathetic activity was significantly and negatively correlated with the scores of the qi-deficiency and the sympathovagal balance was significantly and positively with the latter. The sympathetic activity was significantly and negatively correlated with the scores of phlegm-wet constitution and blood-stasis constitution.3 The difference of HRV parameters between waking state and sleep state was minished in abnormal constitution group, especially the yang-deficiency group, yin-deficiency group and special diathesis group, indicating that the change of the autonomic nervous activity between day and night was minished in abnormal constitution individuals.4 This study explored the characteristics of autonomic nervous activity of different constitutions of TCM and consequently provided one objective and quantized method for the diagnosis and adjustment of the TCMC. |
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