Cardiac autonomic balance in small-for-gestational-age neonates

Evaluation of Nociception during Pediatric Surgery: A Topical Review

The association between intraoperative nociception and increased patient's morbidity is well established. However, hemodynamic parameters, such as heart rate and blood pressure, may result in an inadequate monitor of nociception during surgery. Over the last two decades, different devices have been marketed to "reliably" detect intraoperative nociception. Since the direct measure of nociception is impractical during surgery, these monitors measures nociception surrogates such as sympathetic and parasympathetic nervous systems responses (heart rate variability, pupillometry, skin conductance), electroencephalographic changes, and muscular reflex arc. Each monitor carries its own advantages and disadvantages. The manuscript aims to give an overview of the most up-to-date information available in the literature on current nociceptor monitors available in clinical practice, with particular focus on their applications in pediatrics.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

Perceived Discrimination, Retention, and Diabetes Risk Among American Indians and Alaska Natives in a Diabetes Lifestyle Intervention

Objectives: To examine the association of perceived discrimination with participant retention and diabetes risk among American Indians and Alaska Natives. Methods: Data were drawn from the Special Diabetes Program for Indians-Diabetes Prevention Demonstration Project (N = 2553). Results: Perceived discrimination was significantly and negatively associated with short-term and long-term retention and diabetes risk without adjusting. After controlling for socioeconomic characteristics and clinical outcomes, perceived discrimination was not associated with retention but was significantly associated with less improvement in body mass index (BMI) and high-density lipoprotein (HDL) cholesterol. Every unit increase in the perceived discrimination score was associated with 0.14 kg/m2 less BMI reduction (95% CI: [0.02, 0.26], p = 0.0183) and 1.06 mg/dl lower HDL at baseline (95% CI: [0.36, 1.76], p = 0.0028). Discussion: Among racialized groups, improving retention and health in lifestyle interventions may require investigating perceived discrimination and the broader context of structural racism and colonialism.

Evaluation of prolonged pain in preterm infants with pneumothorax using heart rate variability analysis and EDIN (Échelle Douleur Inconfort Nouveau-Né, neonatal pain and discomfort scale) scores

Purpose

The EDIN scale (Échelle Douleur Inconfort Nouveau-Né, neonatal pain and discomfort scale) and heart rate variability has been used for the evaluation of prolonged pain. The aim of our study was to assess the value of the newborn infant parasympathetic evaluation (NIPE) index and EDIN scale for the evaluation of prolonged pain in preterm infants with chest tube placement due to pneumothorax.

Methods

This prospective observational study assessed prolonged pain in preterm infants with a gestational age between 33 and 35 weeks undergoing installation of chest tubes. Prolonged pain was assessed using the EDIN scale and NIPE index.

Results

There was a significant correlation between the EDIN scale and NIPE index (r=-0.590, P=0.003). Prolonged pain is significantly more severe in the first 6 hours following chest tube installation (NIPE index: 60 [50–86] vs. 68 [45–89], P<0.002; EDIN score: 8 [7–11] vs. 6 [4–8], P<0.001).

Conclusion

Prolonged pain can be accurately assessed with the EDIN scale and NIPE index. However, evaluation with the EDIN scale is time-consuming. The NIPE index can provide instantaneous assessment of prolonged and continuous pain.

The association of birth weight and infant growth with childhood autonomic nervous system activity and its mediating effects on energy-balance-related behaviours-the ABCD study

BACKGROUND

The purpose of this study was to examine the association of birth weight and infant growth with childhood autonomic nervous system (ANS) activity and to assess whether ANS activity mediates the associations of birth weight and infant growth with energy-balance-related behaviours, including energy intake, satiety response, physical activity and screen time.

METHODS

In 2089 children, we prospectively collected birth weight, infant growth defined as conditional weight and height gain between birth and 12 months and-at 5 years-indices of cardiac ANS activity and parent-reported energy-balance-related behaviours. A mediation analysis was conducted, based on MacKinnon's multivariate extension of the product-of-coefficients strategy.

RESULTS

Birth weight and infant height gain were inversely associated with sympathetic, but not parasympathetic, activity at age 5. Infant weight gain was not associated with childhood ANS activity. Infant weight gain was predictive of increased childhood screen time and infant height gain of diminished childhood energy intake, but sympathetic activity did not mediate these associations.

CONCLUSIONS

Low-birth-weight children have higher sympathetic activity, which is considered a risk factor for cardiovascular disease. Height gain in infancy seems to be beneficial for childhood sympathetic activity. However, sympathetic activity was no mediator of the associations of infant growth with childhood energy-balance-related behaviours. As individual differences in ANS activity predict increased risk of cardiovascular disease, these differences may offer insight into the early-life origins of chronic diseases and provide further basis for public health strategies to optimize birth weight and infant growth.

Time domain parameters of heart rate variability in children born as small-for-gestational age

According to metabolic programming theory, small-for-gestational age patients are at high risk of cardiovascular diseases also because of the possible malfunction of the autonomic nervous system. Autonomic disorders can be assessed by heart rate variability. The aims of this study were to compare time domain parameters of heart rate variability in children born as small-for-gestational age and appropriate-for-gestational age and to assess the correlation of the postnatal and current somatic parameters with the time domain parameters. The small-for-gestational age group consisted of 68 children aged 5-10 years who were born with birth weight below the 10th percentile. The appropriate-for-gestational age group consisted of 30 healthy peers, matched in terms of gender and age. On the basis of Holter monitoring, slightly higher average heart rate was observed in the small-for-gestational age group than in the appropriate-for-gestational age group. It was found that all the time domain parameters (SDNN, SDNNi, SDANNi, rMSSD, pNN50) were lower in the small-for-gestational age group than in the appropriate-for-gestational age group. In the small-for-gestational age group, girls had lower heart rate and some of the heart rate variability parameters (SDNN, SDNNi, SDANNi) in comparison with boys. Children born as small-for-gestational age have impaired function of the autonomic nervous system. Moreover, in the small-for-gestational age group, autonomic balance moved towards the sympathetic component, which was evidenced by higher heart rate. Children with faster heart rate and lower heart rate variability parameters may be at risk of cardiovascular disease.

Birth Weight and Its Relationship with the Cardiac Autonomic Balance in Healthy Children

Several studies indicate that the fetal environment plays a significant role in the development of cardiometabolic disease later in life. However, a few studies present conflicting data about the correlation between birth weight and the impairment of cardiac autonomic modulation. The purpose of the present study was to provide further knowledge to elucidate this contradictory relationship. One hundred children aged 5 and 14 years had anthropometric parameters, body composition and blood pressure levels determined. Heart rate variability (HRV) was evaluated by heart rate monitoring, including measurements of both the time and frequency domains. The results showed inverse correlation between the HRV parameters with BMI (RMSSD: P = 0.047; PNN50: P = 0.021; HF: P = 0.041), systolic (RMSSD: P = 0.023; PNN50: P = 0.032) and diastolic (PNN50: P = 0.030) blood pressure levels. On the other hand, there were consistent positive correlations between the HRV parameters and birth weight (RMSSD: P = 0.001; PNN50: P = 0.001; HF: P = 0.002). To determine the effect of birth weight on HRV parameters, we perform multivariate linear regression analysis adjusted for potentially confounding factors (prematurity, gender, age, BMI, physical activity index and SBP levels). These findings were preserved even after adjusting for these confounders. Our results suggested that impaired cardiac autonomic modulation characterized by a reduction in the parasympathetic activity occurs in children with low birth weight. One possible interpretation for these data is that a vagal withdrawal, rather than a sympathetic overactivity, could precede the development of hypertension and other cardiometabolic diseases in children with low birth weight. However, long-term studies should be performed to investigate this possibility.

The Impact of Early Life Stress on Growth and Cardiovascular Risk: A Possible Example for Autonomic Imprinting?

Introduction

Early life stress is imprinting regulatory properties with life-long consequences. We investigated heart rate variability in a group of small children with height below the third percentile, who experienced an episode of early life stress due to heart failure or intra uterine growth retardation. These children appear to develop autonomic dysfunction in later life.

Results

Compared to the healthy control group heart rate variability (HRV) is reduced on average in a group of 101 children with short stature. Low HRV correlates to groups of children born small for gestational age (SGA), children with cardiac growth failure and children with congenital syndromes, but not to those with constitutional growth delay (CGD), who had normal HRV. Reduced HRV indicated by lower RMSSD and High Frequency (HF)-Power is indicating reduced vagal activity as a sign of autonomic imbalance.

Conclusion

It is not short stature itself, but rather the underlying diseases that are the cause for reduced HRV in children with height below the third percentile. These high risk children—allocated in the groups with an adverse autonomic imprinting in utero or infancy (SGA, congenital heart disease and congenital syndromes)—have the highest risk for ‘stress diseases’ such as cardiovascular disease in later life. The incidence of attention deficit disorder is remarkably high in our group of short children.

Intrauterine growth restriction: impact on cardiovascular development and function throughout infancy

Intrauterine growth restriction (IUGR) refers to the situation where a fetus does not grow according to its genetic growth potential. One of the main causes of IUGR is uteroplacental vascular insufficiency. Under these circumstances of chronic oxygen and nutrient deprivation, the growth-restricted fetus often displays typical circulatory changes, which in part represent adaptations to the suboptimal intrauterine environment. These fetal adaptations aim to preserve oxygen and nutrient supply to vital organs such as the brain, the heart, and the adrenals. These prenatal circulatory adaptations are thought to lead to an altered development of the cardiovascular system and "program" the fetus for life long cardiovascular morbidities. In this review, we discuss the alterations to cardiovascular structure, function, and control that have been observed in growth-restricted fetuses, neonates, and infants following uteroplacental vascular insufficiency. We also discuss the current knowledge on early life surveillance and interventions to prevent progression into chronic disease.

A New Framework for the Assessment of Cerebral Hemodynamics Regulation in Neonates Using NIRS

We present a new framework for the assessment of cerebral hemodynamics regulation (CHR) in neonates using near-infrared spectroscopy (NIRS). In premature infants, NIRS measurements have been used as surrogate variables for cerebral blood flow (CBF) in the assessment of cerebral autoregulation (CA). However, NIRS measurements only reflect changes in CBF under constant changes in arterial oxygen saturation (SaO2). This condition is unlikely to be met at the bedside in the NICU. Additionally, CA is just one of the different highly coupled mechanisms that regulate brain hemodynamics. Traditional methods for the assessment of CA do not take into account the multivariate nature of CHR, producing inconclusive results. In this study we propose a newly developed multivariate methodology for the assessment of CHR. This method is able to effectively decouple the influences of SaO2 from the NIRS measurements, and at the same time, produces scores indicating the strength of the coupling between the systemic variables and NIRS recordings. We explore the use of this method, and its derived scores, for the monitoring of CHR using data from premature infants who developed a grade III-IV intra-ventricular hemorrhage during the first 3 days of life.

Vasomotor sympathetic outflow in the muscle metaboreflex in low birth weight young adults

A growing body of evidence suggests that low birth weight (LBW) offspring are associated with long-term structural and functional changes in cardiovascular and neuroendocrine systems. We tested the hypothesis that muscle metaboreflex activation produces exaggerated responses in cardiac autonomic tone (represented by heart rate variability ratio) and cutaneous vascular sympathetic tone (represented by plethysmography pulse wave amplitude) in LBW compared to normal birth weight (NBW) young adults. We recruited 23 LBW (18 females and five males) and 23 NBW (14 females and nine males) University of Zimbabwe students with neonatal clinical cards as proof of birth weight at term. Resting electrocardiogram, pulse waves, and blood pressures were recorded. Participants then underwent a static/isometric handgrip exercise until fatigue and a post-exercise circulatory arrest period of 2 minutes. We observed (results mean ± standard deviation) a greater mean increase in heart rate variability ratio from baseline to exercise for LBW compared to NBW individuals (1.015±1.034 versus [vs] 0.119±0.789, respectively; P<0.05). We also observed a greater mean decrease in plethysmography pulse wave amplitude from baseline to exercise (−1.32±1.064 vs −0.735±0.63; P<0.05) and from baseline to post-exercise circulatory arrest (−0.932±0.998 vs −0.389±0.563; P<0.05) for LBW compared to NBW individuals. We conclude that LBW may be associated with an exaggerated sympathetic discharge in response to muscle metaboreflex.

Individual differences in the cortisol and salivary α-amylase awakening responses in early childhood: relations to age, sex, and sleep

Recent studies have examined post-waking changes in cortisol as a marker of HPA functioning, but questions remain about the stability of this response, as well as its relation to sleep and other ANS markers. The purposes of this study were to a) examine the presence and developmental changes in the cortisol awakening response (CAR) and salivary α-amylase awakening (sAA-AR) in a toddler sample and b) determine whether and how sleep relates to these responses in this age group. We measured cortisol and sAA upon awakening (and 30 min post-waking) and sleep characteristics using actigraphy (e.g., total sleep time, sleep efficiency, number of awakenings) in toddlers (N = 47; 36% female, ages 12-24 months). Forty-six percent of toddlers demonstrated a CAR and 52% demonstrated a sAA-AR. Strength of either response did not change linearly with age. Additionally, likelihood of demonstrating the CAR and sAA-AR was unrelated to age, sex, awakening time, time between samples, and time since feeding. Higher waking cortisol levels were associated with a shorter total sleep time and an earlier awakening. No associations were observed between sleep characteristics and the sAA-AR, ps > .05. Our findings suggest that these awakening responses function independently of sleep in toddlers. Additionally, the lack of change in percentage of children showing a CAR or sAA-AR across these ages suggests that these responses are stable and not emerging reliably across the second year of life.

Influence of the maternal use of labetalol on the neurogenic mechanism for cerebral autoregulation assessed by means of NIRS

Labetalol is a drug used in the treatment of hypertensive disorders of pregnancy (HDP). In a previous study we investigated the influence of the maternal use of labetalol on the cerebral autoregulation (CA) mechanism of neonates. In that study, we found that labetalol induces impaired CA during the first day of life, with CA returning to a normal status by the third day after birth. This effect was hypothesized to be caused by labetalol-induced vasodilation. However, no strong evidence for this claim was found. In this study we aim to find stronger evidence for the vasodilation effect caused by labetalol, by investigating its effect on the neurogenic mechanism (NM) involved in CA. The status of the NM was assessed by means of transfer function analysis between the low frequency content of the autonomic control activity (LFA), obtained by processing of the heart rate (HR), and the regional cerebral oxygen saturation (rScO₂). We found that neonates from mothers treated with labetalol presented a lower LFA and an impaired NM response during the first day of life, with values returning to normal by the end of the third day. These results reflect a vasodilation effect caused by labetalol, and indicate that the impaired CA observed in the previous study is caused by vasodilation.

Salivary alpha-amylase and cortisol responsiveness following electrical stimulation stress in obsessive-compulsive disorder patients

Salivary α-amylase (sAA) serves as a marker of sympathoadrenal medullary system (SAM) activity. Salivary AA has not been extensively studied in obsessive-compulsive disorder (OCD) patients. In the current study, 45 OCD patients and 75 healthy volunteers were assessed with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), the Profile of Mood State (POMS), and the State-Trait Anxiety Inventory (STAI). Measures of heart rate variability (HRV), sAA, and salivary cortisol were also obtained following the application of electrical stimulation stress. The Y-BOCS and POMS Tension-Anxiety, Depression-Dejection, Anger-Hostility, Fatigue, and Confusion scores were significantly increased in patients with OCD compared with healthy controls. In contrast, Vigor scores were significantly decreased in patients with OCD relative to scores in healthy controls. There was no difference in HRV between the patients and the controls. Salivary AA levels in female and male OCD patients were significantly elevated relative to controls both before and after electrical stimulation. In contrast, there were no differences in salivary cortisol levels between OCD patients and controls. The elevated secretion of sAA before and after stimulation may suggest an increased responsiveness to novel and uncontrollable situations in patients with OCD. An increase in sAA might be a characteristic change of OCD.

Salivary mental stress proteins

Of the major diagnostic specimen types, saliva is one of the most easily collected. Many studies have focused on the evaluation of salivary proteins secreted by healthy people and patients with various diseases during responses to acute mental stress. In particular, such studies have focused on cortisol, α-amylase, chromogranin A (CgA), and immunoglobulin A (IgA) as salivary stress markers. Each of these salivary stress markers has its own strengths and weaknesses as well as data gaps related to many factors including collection technique. In this review, we summarize the critical knowledge of the positive and negative attributes and data gaps pertaining to each salivary stress marker.

Study protocol: the relation of birth weight and infant growth trajectories with physical fitness, physical activity and sedentary behavior at 8-9 years of age - the ABCD study

BACKGROUND

Low birth weight and accelerated infant growth have been identified as independent risk factors for childhood and adult obesity and cardiovascular disease. This led to the 'Developmental Origins of Health and Disease' (DOHaD) hypothesis, stating that environmental factors during pregnancy and early postnatal life affect disease risk in later life. There is growing evidence that perinatal factors may influence adult health through the programming of energy balance regulation, including sedentary behavior and physical activity. The present study focuses on the influence of birth weight and infant growth on physical fitness, physical activity and sedentary behavior in 8-9 year old children, as this might partly explain the higher obesity and cardiovascular risk associated with low birth weight and accelerated infant growth. In addition, this study provides the opportunity for a validation study of a linguistic and cross-cultural translated physical activity questionnaire compared to accelerometer data. This article describes the study protocol for this study.

METHODS/DESIGN

This is a study embedded in the Amsterdam Born Children and their Development (ABCD) birth cohort. In 200 children of Dutch ethnicity, physical fitness, physical activity and sedentary behavior were assessed at age 8-9. We measured aerobic fitness using the 20 meter multistage shuttle run test, and neuromuscular fitness using the standing broad jump and handgrip strength test. Sedentary behavior and physical activity levels were measured using accelerometry. All children also completed a translated physical activity questionnaire, the scores of which will be compared to accelerometry data to assess the construct validity of the questionnaire in Dutch school-aged children.

DISCUSSION

This study will be the first population-based prospective cohort study to address the association of both prenatal and postnatal growth with physical fitness and objectively-assessed physical activity and sedentary behavior. This will contribute to a better understanding of the way perinatal growth relate to lifestyle and obesity in later life. The results may guide both future studies in the field of DOHaD, and public health strategies in the prevention of childhood obesity.

Heart rate variability analysis for newborn infants prolonged pain assessment

Pain management is a general concern for healthcare quality. In the particular context of neonatal care, it's well known that an efficient pain management will decrease mortality and morbidity of newborn infants. Furthermore, the plasticity of developing brain is vulnerable to pain and/or stress, that in turn may cause long term neurodevelopmental changes, including altered pain sensitivity and neuroanatomic and behavioural abnormalities. During neonatal intensive care stay, large number of painful procedures are performed, the majority of which are not accompanied by adequate analgesia. Optimal management requires competent pain assessment which can be especially difficult to perform in this non verbal population. We have developed an instantaneous heart rate variability (HRV) analysis method, non intrusive and user-friendly, based on the ECG signal acquisition. This analysis method enabled us to design parameters related to the influence of pain on the Autonomic Nervous System (ANS) activity. This paper presents the application of this method, previously validated for adults under general anesthesia, to the domain of newborn infants prolonged pain assessment.

Effect of antenatal betamethasone administration on neonatal cardiac autonomic balance

Beneficial effects of antenatal glucocorticoid treatment in pregnancies at risk for preterm delivery may entail long-term consequences for the establishment of sympathoadrenergic system balance. We analyzed the cardiac autonomic system activity in neonates with a single course of antenatal betamethasone (2 × 12 mg) treatment by calculating heart rate variability (HRV) time-domain parameters from 24 h ECG recordings and short-term frequency-domain parameters during infant active and resting states. In addition, resting and challenged salivary α-amylase levels were measured in 23 betamethasone-exposed neonates and compared with controls. Indicators for overall HRV (SDNN: p = 0.258; triangular index: p = 0.179) and sympathovagal balance [low- to high-frequency power (LF/HF): p = 0.82 (resting state)] were not significantly different in neonates of the betamethasone treatment group. Parameters mostly influenced by sympathetic activity [SD of the average of valid NN intervals (SDANN): p = 0.184 and SDs of all NN intervals (SDNNi): p = 0.784] and vagal tone [RMSSD: p = 1.0; NN50: p = 0.852; HF: p = 0.785 (resting state)] were unaltered. Resting α-amylase levels were not significantly different in the betamethasone treatment group (p = 0.304); however, α-amylase release after a neonatal challenge was slightly reduced (p = 0.045). Thus, cardiac autonomic balance seems to be preserved in neonates exposed to a single course of antenatal betamethasone treatment.

Effect of lecturing to 200 students on heart rate variability and alpha-amylase activity

The aim of this study was to examine cardiovascular [heart rate variability (HRV)] and autonomic nervous system activation (by evaluating salivary alpha-amylase activity) that occur in professors both to, and after, the delivery of a lecture to 200 students and to determine whether gender is an influencing factor upon response. Fifty-two participants (26 women and 26 men) collected eight unstimulated saliva samples on 2 days (one a working day on which the lecture was given, the other a non-work or rest day). They also completed the Trait version of the State-Trait Anxiety Inventory (STAI) to assess their dispositional anxiety on the rest day and the State section of the STAI 15 min before and 10 min after their lecture, repeated at the same hour on the control (rest) day. The Perceived Stress Scale (PSS) was also recorded 15 min before the lecture. Continuous RR intervals were recorded before and after the lecture and the following HRV parameters were calculated: total spectral power (P (TOT)); the spectral power of the low frequency component (P (LF)); the high frequency component (P (HF)); and the ratio LF/HF. A reduction (P < 0.05) in the HF and HFnu component of HRV and an increase in the LH/HF ratio (P < 0.05) were observed at the end of the lecture. AA activity measured on the teaching day was significantly higher than that noted on the resting day. Lecturing resulted in a significant increase in the secretion of the stress marker alpha-amylase. Men and women did not differ in trait and state anxiety and no gender differences for HRV or AA activity were found.

Neurobehavior in term, small-for-gestational age infants with normal placental function

OBJECTIVE

The goal was to evaluate the neurobehavioral outcomes of term, small-for-gestational age (SGA) newborns with normal placental function.

METHODS

A cohort of consecutive term SGA newborns with normal prenatal umbilical artery Doppler ultrasound findings was created and compared with a group of term infants with size appropriate for gestational age, who were sampled from our general neonatal population. Neonatal behavior was evaluated at corrected age of 40 +/- 1 weeks with the Neonatal Behavioral Assessment Scale. The effect of the study group on each Neonatal Behavioral Assessment Scale area was adjusted, through multivariate analysis of covariance, for smoking during pregnancy, maternal BMI, socioeconomic level, onset of labor, mode of delivery, use of epidural anesthetic medication, gestational age at delivery, postnatal age (in days) at evaluation, and gender.

RESULTS

A total of 202 newborns (102 SGA and 100 appropriate for gestational age) were included. All of the neurobehavioral areas studied were poorer in the SGA group, with significance for attention, habituation, motor, social-interactive, and regulation of state. The average mean differences in scores between the study groups were 0.77 (95% confidence interval: 0.38-1. 14) for attention, 0.64 (95% confidence interval: 0.13-1.14) for habituation, 0.52 (95% confidence interval: 0.31-0.74) for motor, 0.95 (95% confidence interval: 0.54-1.37) for social-interactive, and 0.68 (95% confidence interval: 0.23-1.13) for regulation of state. These differences remained significant after adjustment for potential confounders.

CONCLUSION

Term SGA newborns with no signs of placental insufficiency had poorer neurobehavioral competencies, which suggests delayed neurologic maturation.

Impact of acute psychosocial stress on peripheral blood gene expression pathways in healthy men

We investigated peripheral blood mononuclear cell gene expression responses to acute psychosocial stress to identify molecular pathways relevant to the stress response. Blood samples were obtained from 10 healthy male subjects before, during and after (at 0, 30, and 60 min) a standardized psychosocial laboratory stressor. Ribonucleic acid (RNA) was extracted and gene expression measured by hybridization to a 20,000-gene microarray. Gene Set Expression Comparisons (GSEC) using defined pathways were used for the analysis. Forty-nine pathways were significantly changed from baseline to immediately after the stressor (p < 0.05), implicating cell cycle, cell signaling, adhesion and immune responses. The comparison between stress and recovery (measured 30 min later) identified 36 pathways, several involving stress-responsive signaling cascades and cellular defense mechanisms. These results have relevance for understanding molecular mechanisms of the physiological stress response, and might be used to further study adverse health outcomes of psychosocial stress.

Developmental differences in infant salivary alpha-amylase and cortisol responses to stress

This study examined developmental differences in infants' salivary alpha-amylase (sAA) and cortisol levels and responses to the well-baby exam/inoculation stress protocol at 2, 6, 12, and 24 months of age. Mother-infant pairs (n=85; 45 girls) were assessed during well-baby visits and saliva was sampled before the well-baby exam/inoculation procedure (pre-test) and at 5, 10, and 20 min post-inoculation stress. Older infants (24 months) had higher levels of sAA than younger infants (2, 6 and 12 months). Stress-related sAA increases were evident at 6 and 12 months, but not at 2 or 24 months of age. Stress-related cortisol increases were present at 2 and 6 months, but not at older ages. Mothers had higher sAA levels than their infants, but did not show sAA or cortisol increases to their infants' inoculation. Pre-test, maternal and infant sAA levels were positively correlated (rs .47 to .65) at 6, 12, and 24 months of age, but not at 2 months. These findings suggest that the association between the sympathetic branch of the autonomic nervous system and the secretion of sAA develops between 2 and 6 months of age, when levels of sAA are responsive to exposure to a painful stressor.

Salivary alpha-amylase as a non-invasive biomarker for the sympathetic nervous system: current state of research

Development of new biomarkers is a constantly evolving field of research endeavor in psychoneuroendocrinology. Salivary biomarkers have received special attention since they are readily accessible and easily obtained. Salivary alpha-amylase (sAA) has been proposed as a sensitive biomarker for stress-related changes in the body that reflect the activity of the sympathetic nervous system (SNS), and a growing body of research is accumulating to support the validity and reliability of this parameter. However, questions remain to be answered before sAA can be accepted as an index of SNS activity. This review describes sAA as an emerging biomarker for stress and provides an overview of the current literature on stress-related alterations in sAA. It critically discusses how sAA might reflect changes in the autonomic nervous system. Finally, current and future fields for the application of sAA measurement are outlined.

Determinants of salivary alpha-amylase in humans and methodological considerations

Salivary alpha-amylase (sAA) has been proposed as a marker for activity of the sympathetic nervous system (SNS). Recent studies in support of this hypothesis have led to an increased number of researchers integrating amylase measurements into their study designs. Salivary alpha-amylase is produced locally in the salivary glands, controlled by the autonomic nervous system. This entails some methodological consequences and potential pitfalls that might lead to increased error variance and thus prevent successful testing of hypotheses. The goal of this review is to summarize basic and recent findings on methodological issues and potential factors influencing sAA measurement, and to derive a set of recommendations enabling researchers to successfully using sAA in psychoneuroendocrinological experiments.