Spectral analysis of heart rate variability and respiration during sleep in cocaine-exposed neonates

Sex moderated and RSA mediated effects of prenatal cocaine exposure on behavior problems at age 7

This study was designed to assess whether prenatal cocaine exposure (PCE) is associated with sex differences in behavior problems in middle childhood and whether there are sex differences in the way in which parasympathetic functioning mediates the relations between PCE and behavior problems within a diverse low-income sample. Participants included 164 high risk mother-child dyads including 89 PC exposed children and 75 control children participating in an ongoing longitudinal study. Respiratory sinus arrhythmia (RSA) was measured to assess parasympathetic functioning at 13 months of age and maternal reports of child behavior problems were collected at 7 years of age. Results revealed no significant association between PCE and behavior problems for the full sample. A 2 × 2 Anova revealed a significant interaction between PCE and child sex on internalizing, externalizing, and total behavior problems (F (3, 160) = 13.45, p < .001) with cocaine exposed females averaging the highest behavior problem scores. Results also revealed a statistically significant indirect effect linking cocaine exposure to lower externalizing problems via lower baseline RSA among males. Findings indicate that cocaine exposed females may be more vulnerable to developing behavior problems than cocaine exposed males and that high baseline RSA may present a sex specific risk factor for externalizing problems among exposed males.

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.

Autonomic functioning among cocaine-exposed kindergarten-aged children: Examination of child sex and caregiving environmental risk as potential moderators

The purpose of this study was to examine the hypothesis that child sex moderates the association between prenatal cocaine exposure (PCE) and autonomic functioning as well as to examine the role that caregiving environmental risk played in sex differences in autonomic functioning among exposed children. Measures of the parasympathetic nervous system (indexed by respiratory sinus arrhythmia [RSA]) and the sympathetic nervous system (indexed by skin conductance level [SCL]) were obtained from 146 (75 cocaine-exposed, 38 male; and 71 nonexposed, 36 male) children during baseline and a task designed to elicit negative affect (NA). We also examined the role of caregiving environmental risk as a moderator of the association between PCE and autonomic functioning separately for boys and girls. PCE boys had a significantly higher baseline RSA and lower baseline SCL than PCE girls or nonexposed children. Environmental risk also moderated the association between PCE and baseline RSA for boys, but not girls, such that boys with PCE and high environmental risk had the highest baseline RSA. These findings indicate that exposed boys had significantly lower levels of sympathetic activation while at rest. However, for autonomic reactivity, the exposed girls had a larger change in both RSA and SCL relative to nonexposed girls while exposed boys had significantly smaller increases in SCL during environmental challenge. Finally, girls with both PCE and high environmental risk had the highest levels of parasympathetic reactivity during challenge. These results underscore the importance of examining sex differences and considering comorbid environmental risk factors when examining developmental outcomes in cocaine-exposed children and highlight the complexity involved with understanding individual differences in cocaine-exposed populations.

The entropy of RR intervals is associated to gestational age in full-term newborns with adequate weight for gestational age

Introduction: The variability of successive RR intervals has been pointed out as an indicator of systemic homeostasis. The entropy of successive RR intervals is associated with a greater adaptive capacity, which is essential after childbirth, characterized by a change from an intrauterine environment that constantly adapts to the fetal demands, to an extrauterine environment that requires constant biological adaptations by the neonate.Objectives: To analyze the association between gestational age (GA) and the entropy of RR intervals in term infants with adequate birth weight in the first hours of extrauterine life.Methods: In a cross-sectional study design maternal, labor and neonatal characteristics were collected from the obstetric records. Successive RR intervals were recorded from neonates up to 72 hours (i.e. 3 days) of birth.Subjects: Fifty term infants, healthy and with adequate birth weight. Outcome measures: the variability of RR intervals was analyzed obtaining the entropy of 1000 successive RR intervals. Pearson's correlation was used to evaluate the association between GA and the entropy of successive RR intervals, while linear regression was used to obtain the coefficient of determination (r²) as well as a prediction model. The adequacy of the prediction model was evaluated using the Komolgorov-Smirnov test to evaluate the residuals distribution.Results: There was a positive and significant association between the studied variables (r = 0.437; p = .002). The coefficient of determination allowed us to infer that approximately 19.3% of the RR interval entropy from the studied sample can be explained by the GA (r² = 0.193; p = .002). The analysis of the residuals distribution confirmed that the regression model obtained here was adequate.Conclusion: Our results indicate that, even within a normal range of GA (≥37 a < 42 weeks) and birth weight, a longer intrauterine life allows a greater entropy of successive RR intervals, indicating a greater maturation of biological systems and adaptive capacity.

Behavior problems among cocaine exposed children: role of physiological regulation and parenting

This study examined interrelations between prenatal cocaine exposure, child autonomic regulation, parenting behavior and child sex on parent-reported behavior problems at 36 months of age. We hypothesized that respiratory sinus arrhythmia (RSA) at 13 months of age would mediate the relation between cocaine exposure and behavior problems. We also hypothesized that child sex, maternal negative affect, and maternal sensitivity observed at 13 months of age would moderate the relation between RSA and behavior problems. Results revealed that cocaine exposure predicted low baseline RSA and low RSA withdrawal during a negative affect task. Low baseline RSA, in turn, predicted fewer behavior problems offering support for an indirect association between cocaine exposure and behavior problems. The association between baseline RSA and behavior problems was further moderated by maternal negative affect such that high baseline RSA was more strongly related to behavior problems under conditions of high compared to low maternal negative affect. Results also revealed a near significant trend for baseline RSA to be more strongly related to behavior problems among boys than girls. These findings highlight several possible pathways toward behavior problems among cocaine exposed children.

Physiological Regulation at 9 Months of Age in Infants Prenatally Exposed to Cigarettes

The primary purpose of this study was to examine the association between prenatal cigarette exposure and physiological regulation at 9 months of age. Specifically, we explored the possibility that any association between prenatal cigarette exposure and infant physiological regulation was moderated by postnatal environmental tobacco smoke (ETS) exposure or infant gender. We evaluated whether male infants with prenatal cigarette exposure or infants who were also exposed to ETS after birth had the highest levels of physiological dysregulation. Respiratory sinus arrhythmia (RSA) was obtained from 206 (142 exposed and 64 nonexposed) infants during a baseline period and during procedures designed to elicit both positive and negative affect. There was a significant suppression of RSA during the negative affect task for nonexposed infants but not for exposed infants. Postnatal ETS exposure did not moderate this association; however, gender did moderate this association such that boys with prenatal cigarette exposure had a significant increase in RSA rather than the suppression seen among both nonexposed boys and girls. These results provide additional support for the idea that boys are particularly vulnerable to the effects of prenatal cigarette exposure.

Profiles of Reactivity in Cocaine-Exposed Children

This study explored the possibility that specific, theoretically consistent profiles of reactivity could be identified in a sample of cocaine-exposed infants and whether these profiles were associated with a range of infant and/or maternal characteristics. Cluster analysis was used to identify distinct groups of infants based on physiological, behavioral and maternal reported measures of reactivity. Five replicable clusters were identified which corresponded to 1) Dysregulated/High Maternal Report Reactors, 2) Low Behavioral Reactors, 3) High Reactors, 4) Optimal Reactors and 5) Dysregulated/Low Maternal Report Reactors. These clusters were associated with differences in prenatal cocaine exposure status, birthweight, maternal depressive symptoms, and maternal negative affect during mother-infant interactions. These results support the presence of distinct reactivity profiles among high risk infants recruited on the basis of prenatal cocaine exposure and demographically similar control group infants not exposed to cocaine.

Cardiac autonomic function in older adults with sleep-disordered breathing

We searched for possible associations between various measures of severity of sleep-disordered breathing (SDB) and indices of cardiac autonomic function in older subjects (>60 years). Twenty four overnight unattended homebased based polysomnograms obtained from the Sleep Heart Health Study were analyzed using spectral analysis. For each subject, six autonomic indices reflecting heart rate variability were quantitatively determined during wakefulness, REM sleep and non-REM sleep. Each individual autonomic marker was regressed against each of 4 measures of SDB, including the respiratory disturbance index (RDI), respiratory oscillation index, cumulative oxygen desaturation, and arousal index. In general, we found no correlation between any of these measures of SDB severity and each of the autonomic indices. However, mean heart rate was found to decrease as RDI increased. As well, the ratio of low-frequency to high-frequency power (LHR) decreased with increasing RDI. Contrary to previous reports, our preliminary findings suggest that sympathetic activity decreases with increasing severity of SDB. This paradoxical association between SDB and cardiac autonomic function may be the result of natural compensatory mechanisms at work, allowing some subjects with SDB to be protected from systemic hypertension or other cardiovascular diseases. Supported in part by NIH Grants HL076375, EB001978, HL63463 and HL53941.

Cocaine Exposure and Children's Self-Regulation: Indirect Association via Maternal Harshness

OBJECTIVES

This study examined the association between prenatal cocaine exposure and children's self-regulation at 3 years of child age. In addition to direct effects of prenatal cocaine exposure on children's self-regulation, we hypothesized there would be indirect associations between cocaine exposure and self-regulation via higher maternal harshness and poor autonomic regulation in infancy.

METHODS

The sample consisted of 216 mother-infant dyads recruited at delivery from local area hospitals (116 cocaine-exposed, 100 non-exposed). Infant autonomic regulation was measured at 7 months of age during an anger/frustration task, maternal harshness was coded from observations of mother-toddler interactions at 2 years of age, and children's self-regulation was measured at 3 years of age using several laboratory paradigms.

RESULTS

Contrary to hypotheses, there were no direct associations between maternal cocaine use during pregnancy and children's self-regulation. However, results from testing our conceptual model including the indirect effects via maternal harshness or infant parasympathetic regulation indicated that this model fit the data well, χ(2) (23) = 34.36, p > 0.05, Comparative Fit Index = 0.95, RMSEA = 0.05. Cocaine using mothers displayed higher intensity of harshness toward their toddlers during lab interactions across a variety of tasks at 2 years of age (β = 0.23, p < 0.05), and higher intensity of harshness at 2 years was predictive of lower self-regulation at 3 years (β = -0.36, p < 0.01). Maternal cocaine use was also predictive of a non-adaptive increase in respiratory sinus arrhythmia (RSA) from baseline to the negative affect task, but RSA change in infancy was not predictive of self-regulation at 3 years.

CONCLUSION

RESULTS are supportive of animal models indicating higher aggression among cocaine treated dams, and indicate that higher maternal harshness among cocaine using mothers is predictive of child self-regulatory outcomes in the preschool period.

Maternal cocaine use and mother-toddler aggression

This study examined the direct and indirect associations between maternal cocaine use during pregnancy and mother-toddler aggression in an interactive context at 2 years of child age. We hypothesized that in addition to direct effects of cocaine exposure on maternal and child aggression, the association between maternal cocaine use and mother-toddler aggression may be indirect via higher maternal psychiatric symptoms, negative affect, or poor infant autonomic regulation at 13 months. Participants consisted of 220 (119 cocaine exposed, 101 non-cocaine exposed) mother-toddler dyads participating in an ongoing longitudinal study of prenatal cocaine exposure. Results indicated that mothers who used cocaine during pregnancy displayed higher levels of aggression toward their toddlers compared to mothers in the control group. Results from model testing indicated significant indirect associations between maternal cocaine use and maternal aggression via higher maternal negative affect as well as lower infant autonomic regulation at 13 months. Although there were no direct associations between cocaine exposure and toddler aggression, there was a significant indirect effect via lower infant autonomic regulation at 13 months. Results highlight the importance of including maternal aggression in predictive models of prenatal cocaine exposure examining child aggression. Results also emphasize the important role of infant regulation as a mechanism partially explaining associations between cocaine exposure and mother-toddler aggression.

The association between prenatal cocaine exposure and physiological regulation at 13 months of age

BACKGROUND

This study examined the association between prenatal cocaine exposure (PCE) and autonomic regulation at 13 months of age.

METHODS

Measures of respiratory sinus arrhythmia (RSA) were obtained from 156 (79 exposed, and 77 nonexposed) infants during baseline and during tasks designed to elicit positive (PA) and negative affect (NA).

RESULTS

There was a significant suppression of RSA during the negative affect task for nonexposed infants but not for exposed infants. Maternal symptoms of depression or anxiety (MDA) did not mediate this association. However, gender and MDA did moderate this association such that exposed boys and exposed infants whose mothers had higher levels of MDA had an increase in RSA during a task designed to elicit NA rather than the typical pattern of RSA suppression.

CONCLUSIONS

These results suggest that there are several possible pathways from PCE to physiological dysregulation during late infancy.

Emotional arousal in cocaine exposed toddlers: prediction of behavior problems

Prenatal cocaine exposure (PCE) may be associated with alterations in children's developing emotional arousal and regulation systems.

OBJECTIVE

We examined emotional responses to a frustrating task and subsequent behavior problems in 225 2 1/2 year olds (129 Prenatally Cocaine and Other Drug Exposed [PCE], 30 Non Cocaine but other drug Exposed [NCE], 66 Non Drug Exposed [NDE]).

METHOD

Children's behaviors in a frustrating toy wait task at age 2 1/2 were coded for emotional arousal and regulation behaviors.

RESULTS

Findings indicated a trend for PCE toddlers to show greater agitated emotional arousal than NCE and NDE toddlers. Further, PCE boys made more references to their caregivers in the task than NDE boys. Higher agitated arousal at age 2 1/2 years was related to greater decreases in externalizing behaviors through age 5 1/2 years.

CONCLUSION

Findings suggest a link between cocaine exposure and emotional arousal and regulation and highlight the need to understand complex relations between emotion and risk for later psychopathology in exposed youth.

Short- and long-term adverse effects of cocaine abuse during pregnancy on the heart development

The effect of cocaine on the developing fetus is a topic of considerable interest and debate. One of the potential effects of fetal cocaine exposure is damage to the developing heart. This review provides an overview of the current understanding of the short- and long-term effects of fetal cocaine exposure on the heart in both humans and animal models. Human studies are still preliminary but have suggested that fetal cocaine exposure impacts on the developing heart. Studies in animal models provide strong evidence for a programming effect resulting in detrimental long-term changes to the heart induced by fetal cocaine exposure. In the rat model, fetal cocaine results in apoptosis in the term heart, left ventricular remodeling and myocyte hypertrophy, as well as increased sensitivity to ischemia/reperfusion injury in the adult male offspring. The rat model has also shown evidence of epigenetic modifications in response to intrauterine cocaine. Increased DNA methylation of promoter regions leads to a long-term decrease in the expression of the cardioprotective gene, PKCepsilon. The current data shows fetal cocaine exposure has significant immediate and long-term cardiac consequences in animal models and while human studies are still incomplete they suggest this phenomenon may also be significant in humans exposed to cocaine during development.

A Longitudinal Examination of Physiological Regulation in Cocaine-Exposed Infants Across the First 7 Months of Life

This study examined the association between prenatal exposure to cocaine and physiological regulation across the first 7 months of age. Measures of respiratory sinus arrhythmia (RSA) were obtained from 169 (82 cocaine-exposed and 87 nonexposed) infants during baseline periods at 1 month and 7 months of age and during tasks designed to elicit positive and negative affect at 7 months of age. After controlling for maternal age, gestational age, and obstetrical risk, structural equation modeling indicated that the association between prenatal exposure to cocaine and baseline RSA at 7 months of age was direct even in the presence of an indirect effect through baseline RSA at 1 month of age. There were no indirect effects through maternal affect during mother-infant interactions assessed at 1 month of age. Analyses also indicated a direct association between prenatal exposure to cocaine and RSA regulation to negative affect at 7 months of age.

Ontogeny of EEG-sleep from neonatal through infancy periods

Serial neonatal and infant electroencephalographic (EEG)-polysomnographic studies document the ontogeny of cerebral and noncerebral physiologic behaviors based on visual inspection or computer analyses. EEG patterns and their relationship to other physiologic signals serve as templates for normal brain organization and maturation, subserving multiple interconnected neuronal networks. Interpretation of serial EEG-sleep patterns also helps track the continuity of brain functions from intrauterine to extrauterine time periods. Recognition of the ontogeny of behavioral and electrographic patterns provides insight into the developmental neurophysiological expression of neural plasticity. Sleep ontogenesis from neonatal and infancy periods documents expected patterns of postnatal brain maturation, which allows for alterations from genetically programmed neuronal processes under stressful and/or pathological conditions. Automated analyses of cerebral and noncerebral signals provide time- and frequency-dependent computational phenotypes of brain organization and maturation in healthy or diseased states. Research pertaining to the developmental origins of health and disease can use these computational phenotypes to design longitudinal studies for the assessment of gene-environment interactions. Computational strategies may ultimately improve our diagnostic skills to identify special-needs children and to track the neurorehabilitative care of the high-risk fetus, neonate, and infant.

Prenatal cocaine and other substance exposure: effects on infant autonomic regulation at 7 months of age

This study examined the association between prenatal exposure to cocaine and autonomic regulation at 7 months of age. Heart rate (HR) and respiratory sinus arrhythmia (RSA) were obtained from 154 (79 exposed, and 75 nonexposed) infants during baseline and tasks designed to elicit positive and negative affect. Cocaine-exposed infants had higher HR during the positive affect task. There was a significant suppression of RSA during the negative affect task for nonexposed infants but not for exposed infants. Fetal growth and maternal caregiving behavior did not mediate or moderate this association. These results provide additional support for an association between prenatal cocaine exposure and dysregulation during infancy.

Autonomic alterations in cocaine-exposed neonates following orthostatic stress

We investigated the effects of prenatal cocaine exposure (PCE) on heart rate (HR) and heart rate variability (HRV) in the presence of orthostatic stress among near- and full-term neonates. PCE infants (n = 21) and controls (n = 23) were enrolled within 120 h of birth. ECG was recorded for an hour during quiet sleep, 30 min in supine position and then 30 min in an inclined position. Linear mixed models were used to analyze HR and HRV in the time domain and wavelet and power spectrum analyses in the frequency domain. PCE infants had tachycardia both before (p = 0.091) and after tilting (p = 0.015), but with a clear interaction between PCE and orthostatic stress (p = 0.049). Compared with controls, PCE infants had a delayed and prolonged reaction to orthostatic stress. There was also a pronounced interaction with regard to log-transformed SDDRR, a measure of HRV (p = 0.049). Controls experienced an instantaneous increase in log (SDDRR) followed by a prompt return to normal levels, while PCE infants had a gradual increase that did not dissipate quickly. Frequency-domain analyses also distinguished between the cocaine-exposed infants and the controls. Results suggest that the effects of PCE on the development of sympathetic and parasympathetic systems could lead to altered cardiovascular function.

The association between maternal cocaine use during pregnancy and physiological regulation in 4- to 8-week-old infants: an examination of possible mediators and moderators

OBJECTIVE

To examine the association between maternal cocaine use during pregnancy and physiological measures of regulation, which included heart rate (HR) and respiratory sinus arrhythmia (RSA).

METHODS

Potential mediators and moderators of this association were explored. Participants were 141 mother-infant dyads (77 cocaine exposed and 64 nonexposed) recruited at birth. Average infant HR and RSA was assessed at 4-8 weeks of age during a 15 minute period of sleep.

RESULTS

Results indicated a dose-dependent effect of prenatal exposure to cocaine on RSA. There was no evidence that fetal growth or other prenatal exposure to substances mediated this association or that fetal growth or maternal age moderated this association. Regression analyses also indicated that birth weight (BW), but not birthlength (BL), head circumference (HC) or other substance use, mediated the association between prenatal exposure to cocaine and heart rate.

CONCLUSIONS

These results suggest that cocaine exposure is associated with physiological regulation at 4-8 weeks of age and highlight the importance of considering level of exposure when assessing infant outcomes.

Automated State Analyses: Proposed Applications to Neonatal Neurointensive Care

The two principal challenges of neonatal physiologic monitoring device are: (1) the development of computational strategies that consider the rudimentary forms of neonatal sleep state especially for preterm infants and (2) any physiologic monitoring device for clinical applications in a neonatal intensive care setting must be small, portable, and user-friendly. Our multicenter neonatal sleep consortium has acquired more than 1,100 multihour EEG-sleep recordings on over 370 neonates, ranging from 24 to 44 weeks gestation. Each recording was visually-scored for state, arousals, movements, and rapid eye movements, which were used as templates when applying spectral analyses. The authors have defined a brain dysmaturity index to represent functional brain reorganization as the prenate matures to a full-term age; delayed or accelerated physiologic behaviors have been described for the preterm cohort when compared to the full-term group at the same postmenstrual age. Seven EEG-sleep measures comprise this index: quiet sleep percentage, sleep cycle length, rapid eye movements, arousals, spectral beta EEG energies, spectral EEG correlations, and a spectral measure of respiratory regularity. Linear and nonlinear computational algorithms are being developed to automate the computation of the dysmaturity index and to identify new feature types that correlate with dysmaturity. Automated neonatal sleep monitoring system can potentially improve neonatal neurointensive care by facilitating analyses of pervasive neonatal brain disorders expressed primarily as altered sleep state organization, and help predict altered developmental trajectories of children at higher risk for neurologic sequelae.

Cocaine effects on the developing brain: current status

The present paper reports on the results obtained in a rabbit model of prenatal cocaine exposure that mimics the pharmacokinetics of crack cocaine in humans, and relates these findings to studies in other species including humans. A general finding is that prenatal exposure to cocaine during neurogenesis produces dysfunctions in signal transduction via the dopamine D(1) receptor and alterations in cortical neuronal development leading to permanent morphological abnormalities in frontocingulate cortex and other brain structures. Differences in the precise effects obtained appear to be due to the dose, route and time of cocaine administration. Related to these effects of in utero cocaine exposure, animals demonstrate permanent deficits in cognitive processes related to attentional focus that have been correlated with impairment of stimulus processing in the anterior cingulate cortex. The long-term cognitive deficits observed in various species are in agreement with recent reports indicating that persistent attentional and other cognitive deficits are evident in cocaine-exposed children as they grow older and are challenged to master more complex cognitive tasks.