Postural variations in Cardio Stress Index scores

Numerous factors influence heart rate variability, including age, exercise and posture. The Cardio Stress Index (CSI) is a transformed measure of heart rate variability that is determined via a miniature digital multi-channel electrocardiogram system. Although the CSI and heart rate variability are reportedly analogous, little is known about how the two concepts compare in peer-reviewed research. The aim of this study was to examine the differences between CSI and heart rate as measured on a mini- electrocardiogram device when subjects were sitting upright and when they were lying down (in supine position). This is a case-series study with no intervention or follow-up. Sitting and supine CSI and heart rate readings were compared in a random sample of 55 women volunteers recruited through advertising in Pretoria, South Africa. The mean age of the sample was 25.01 years (SD = 7.56). After completing a biographical questionnaire, subjects’ CSI and heart rates were evaluated using a digital medical device, the ViportTM. The combined CSI for the group was elevated above the normative value of 20% (31.00%; SD = 14.03). The seated, supine and combined CSI all differed significantly from one another (p<0.05) and the CSI was significantly correlated with heart rate (p=0.41). In conclusion, the CSI readings, like heart rate variability measurements taken in different postures, cannot be used interchangeably in clinical practice or in research. The CSI appears to mirror existing research evidence on heart rate variability and posture.http://www.ajol.info/journal_index.php?jid=153&ab=ajpher

Stress response index for adverse childhood experience based on fusion of hypothalamus pituitary adrenocorticol and autonomic nervous system biomakers

Early life exposure to stress such as adverse childhood experiences has been suggested to cause changes in physiological processes and alteration in stress response magnitude which might have significant impact on health later in life. For this reason, detection of this altered stress response can be used as an indicator for future health. To date, there is no study that utilized this information to indicate future health. In order to detect the altered stress response, biomarkers that represent both Autonomic Nervous System (ANS) and Hypothalamic-Pituitary-Adrenocorticol (HPA) is proposed. Among the available biomarkers, Heart Rate Variability (HRV) has been proven as a powerful biomarker that represents ANS. Meanwhile, salivary cortisol has been suggested as a biomarker that reflects the HPA. Even though many studies used multiple biomarkers to measure the stress response, the results for each biomarker were analysed separately. Therefore, this study fuses the biomarker that represents both ANS and HPA as a single measure, proposes a new method to classify the stress response based on adverse childhood experience in the form of stress response index as a future health indicator. Electrocardiograph, blood pressure, pulse rate and Salivary Cortisol (SCort) were collected from 23 participants, 12 participants who had adverse childhood experience while the remaining 11 act as the control group. The recording session was done during a Paced Auditory Serial Addition Test (PASAT). HRV features were then extracted from the electrocardiograph (ECG) using time, frequency, time-frequency analysis, and wavelet transform. Following this, genetic algorithm was implemented to select a subset of 12 HRV features from 83 features. Next, the selected HRV features were combined with other biomarkers using parallel and serial fusion for performance comparison. Using Support Vector Machine (SVM), results showed that fused feature of the parallel fusion, so-called Euclidean distance (ed), demonstrated the highest performance with 80.0% accuracy, 83.3% sensitivity and 78.3% specificity. Finally, the fused feature of the Euclidean distance was fed into SVM in order to model the stress response index as an indicator for future health. This index was validated using all samples and achieved 91.3% accuracy. From this study, a new method based on HRV-SCort biomarker using Euclidean distance and SVM named as ed-SVM was proven to be an effective method to classify the stress response and could further be used to model a stress response index. This index can then be benefited as an indicator for future health to improve the health care management in adulthood

Stress response index for adverse childhood experience based on fusion of hypothalamus pituitary adrenocorticol and autonomic nervous system biomarkers

Early life exposure to stress such as adverse childhood experiences has been suggested to cause changes in physiological processes and alteration in stress response magnitude which might have significant impact on health later in life. For this reason, detection of this altered stress response can be used as an indicator for future health. To date, there is no study that utilized this information to indicate future health. In order to detect the altered stress response, biomarkers that represent both Autonomic Nervous System (ANS) and Hypothalamic-Pituitary-Adrenocorticol (HPA) is proposed. Among the available biomarkers, Heart Rate Variability (HRV) has been proven as a powerful biomarker that represents ANS. Meanwhile, salivary cortisol has been suggested as a biomarker that reflects the HPA. Even though many studies used multiple biomarkers to measure the stress response, the results for each biomarker were analysed separately. Therefore, this study fuses the biomarker that represents both ANS and HPA as a single measure, proposes a new method to classify the stress response based on adverse childhood experience in the form of stress response index as a future health indicator. Electrocardiograph, blood pressure, pulse rate and Salivary Cortisol (SCort) were collected from 23 participants, 12 participants who had adverse childhood experience while the remaining 11 act as the control group. The recording session was done during a Paced Auditory Serial Addition Test (PASAT). HRV features were then extracted from the electrocardiograph (ECG) using time, frequency, time-frequency analysis, and wavelet transform. Following this, genetic algorithm was implemented to select a subset of 12 HRV features from 83 features. Next, the selected HRV features were combined with other biomarkers using parallel and serial fusion for performance comparison. Using Support Vector Machine (SVM), results showed that fused feature of the parallel fusion, so-called Euclidean distance (ed), demonstrated the highest performance with 80.0% accuracy, 83.3% sensitivity and 78.3% specificity. Finally, the fused feature of the Euclidean distance was fed into SVM in order to model the stress response index as an indicator for future health. This index was validated using all samples and achieved 91.3% accuracy. From this study, a new method based on HRV-SCort biomarker using Euclidean distance and SVM named as ed-SVM was proven to be an effective method to classify the stress response and could further be used to model a stress response index. This index can then be benefited as an indicator for future health to improve the health care management in adulthood

Pupillary light reflex in children with autism spectrum disorders

Pupillary light reflex (PLR) refers to the phenomenon of pupil size changing with respect to retinal illumination. It's a noninvasive, functional test which can reveal a rich set of information about nervous system. Abnormal PLR in children with autism spectrum disorders (ASD) was previously reported in a small population. In this research, a series of systematic studies were carried out to investigate the association of atypical PLR with ASD in a large population. An experimental protocol was developed to measure PLR simultaneously with heart rate variability (HRV), a commonly used autonomic nervous system (ANS) measure. Our results indicate that variations of PLR and HRV are not associated in typically developing children. However, significant age effects on both PLR and HRV were observed in this population. In typically developing children, the resting pupil diameter increased with age significantly up to age 12. PLR constriction increased with age in children younger than 8 years old and reached a plateau thereafter. PLR latency decreased significantly from 6 to 9 years and stabilized thereafter. The average heart rate (AHR) decreased with age in typically developing children. Standard deviation of normal-to-normal intervals (SDNN) showed little change before 12 years of age but was increased in older children. High frequency normalized power (HFN) decreased with age in typically developing (TD) group. PLR and HRV were also measured in 152 children with ASD and 36 children with non-ASD neurodevelopmental disorders (NDDs). The results showed atypical PLR in the ASD group including longer PLR latency, reduced relative constriction amplitude, and shorter constriction/redilation time. Similar atypical PLR parameters were observed in the NDD group. The ASD and NDD groups had faster AHR than the TD group. The NDD group also showed a significantly faster AHR than the ASD group. The age effect on PLR latency which was observed in typically developing children of 6-9 years old was not observed in the ASD and NDD gro

The effect of brief mindfulness training on distress tolerance, heart rate variability and alcohol consumption

This thesis examines the effectiveness of brief experimental mindfulness training in reducing alcohol craving and consumption in relation to distress tolerance and heart rate variability (HRV) among harmful/hazardous drinkers. Part one presents a literature review examining the effects of mindfulness on HRV. The review of 16 studies concluded that mindfulness is associated with HRV and increased HRV in a high frequency range was observed in both healthy individuals and in patient groups. Methodological limitations of the current literature and recommendations for future research are discussed. Part two is an empirical study involving a randomized controlled design examining the effects of brief mindfulness training on distress tolerance, heart rate variability and alcohol consumption. The results indicated that there was a significant increase in HRV in the relaxation group but no significant change in the mindfulness group. Participants who had increased HRV consumed less alcohol immediately after training, but interestingly only the participants in the mindfulness group consumed less alcohol after seven days. The increase in distress tolerance was similar between groups. This paper is part of a joint theses project with another Trainee Clinical Psychologist, Shirley Serfaty (2016). Her study involved a cue reactivity procedure to examine the effects of mindfulness on craving and negative affect. Part three provides a critical appraisal of the empirical study. It discusses methodological issues such as challenges with developing mindfulness/relaxation scripts, choice of behavioural and physiological measures and maintaining superior follow up rates. It also includes a brief discussion of my interest in the field of mindfulness and my experiences of conducting this research