Physiological correlates of neurobehavioral disinhibition that relate to drug use and risky sexual behavior in adolescents with prenatal substance exposure.

Physiological correlates of behavioral and emotional problems, substance use onset and initiation of risky sexual behavior have not been studied in adolescents with prenatal drug exposure. We studied the concordance between baseline respiratory sinus arrhythmia (RSA) at age 3 and baseline cortisol levels at age 11. We hypothesized that children who showed concordance between RSA and cortisol would have lower neurobehavioral disinhibition scores which would in turn predict age of substance use onset and first sexual intercourse. The sample included 860 children aged 16 years participating in the Maternal Lifestyle Study, a multisite longitudinal study of children with prenatal exposure to cocaine and other substances. Structural equation modeling was used to test pathways between prenatal substance exposure, early adversity, baseline RSA, baseline cortisol, neurobehavioral disinhibition, drug use, and sexual behavior outcomes. Concordance was studied by examining separate male and female models in which there were statistically significant interactions between baseline RSA and cortisol. Prenatal substance exposure was operationalized as the number of substances to which the child was exposed. An adversity score was computed based on caregiver postnatal substance use, depression and psychological distress, number of caregiver changes, socioeconomic and poverty status, quality of the home environment, and child history of protective service involvement, abuse and neglect. RSA and cortisol were measured during a baseline period prior to the beginning of a task. Neurobehavioral disinhibition, based on composite scores of behavioral dysregulation and executive dysfunction, substance use and sexual behavior were derived from questionnaires and cognitive tests administered to the child. Findings were sex specific. In females, those with discordance between RSA and cortisol (high RSA and low cortisol or low RSA and high cortisol) had the most executive dysfunction which, in turn, predicted earlier initiation of alcohol by age 16. Among boys, there also existed a significant baseline RSA by baseline cortisol interaction. Boys with low baseline RSA and high baseline cortisol had the highest levels of behavioral dysregulation. This increase in behavioral dysregulation was in turn related to initiation of alcohol use by age 16 and lower age of first sexual intercourse. We found sex-specific pathways to the initiation of alcohol use and risky sexual behavior through the combined activity of parasympathetic and neuroendocrine functioning. The study of multiple physiological systems may suggest new pathways to the study of age of onset of substance use and engagement in risky sexual behavior in adolescents.

Cortisol reactivity to social stress as a mediator of early adversity on risk and adaptive outcomes.

Children chronically exposed to stress early in life are at increased risk for maladaptive outcomes, though the physiological mechanisms driving these effects are unknown. Cortisol reactivity was tested as a mediator of the relation between prenatal substance exposure and/or early adversity on adaptive and maladaptive outcomes. Data were drawn from a prospective longitudinal study of prenatal substance exposure (N = 860). Cortisol reactivity was assessed at age 11. Among African Americans, prenatal substance exposure exerted an indirect effect through early adversity and cortisol reactivity to predict externalizing behavior, delinquency, and a positive student-teacher relationship at age 11. Decreased cortisol reactivity was related to maladaptive outcomes, and increased cortisol reactivity predicted better executive functioning and a more positive student-teacher relationship.

The contributions of early adverse experiences and trajectories of respiratory sinus arrhythmia on the development of neurobehavioral disinhibition among children with prenatal substance exposure.

Neurobehavioral disinhibition (ND) is a complex condition reflecting a wide range of problems involving difficulties with emotion regulation and behavior control. Respiratory sinus arrhythmia (RSA) is a physiological correlate of emotion regulation that has been studied in a variety of at-risk populations; however, there are no studies of RSA in children with ND. Data were drawn from a prospective longitudinal study of prenatal substance exposure that included 1,073 participants. Baseline RSA and RSA reactivity to an attention-demanding task were assessed at 3, 4, 5, and 6 years. ND was assessed at ages 8/9, 11, and 13/14 years via behavioral dysregulation and executive dysfunction composite measures. Greater exposure to early adversity was related to less RSA reactivity at 3 years, increases in RSA reactivity from ages 3 to 6 years, and increased behavioral dysregulation from ages 8/9 to 13/14. RSA reactivity was examined as a moderator of the association between early adversity and changes in ND. A significant Early Adversity × RSA Reactivity quadratic interaction revealed that children with decelerations in RSA reactivity exhibited increases in behavioral dysregulation, regardless of their exposure to early adversity. However, greater exposure to early adversity was related to greater increases in behavioral dysregulation, but only if children exhibited accelerations in RSA reactivity from ages 3 to 6 years. The results contribute to our understanding of how interactions across multiple levels of analysis contribute to the development of ND.

Prenatal substance exposure: neurobiologic organization at 1 month.

OBJECTIVE: To examine the autonomic nervous system and neurobehavioral response to a sustained visual attention challenge in 1-month-old infants with prenatal substance exposure. STUDY DESIGN: We measured heart rate, respiratory sinus arrhythmia, and neurobehavior during sustained visual orientation tasks included in the Neonatal Intensive Care Unit Network Neurobehavioral Scale in 1129 1-month-old infants with prenatal substance exposure. Four groups were compared: infants with prenatal cocaine and opiate exposure, infants with cocaine exposure, infants with opiate exposure, and infants with exposure to other substances (ie, alcohol, marijuana, and tobacco). RESULTS: The infants with prenatal exposure to both cocaine and opiates had the highest heart rates and lowest levels of respiratory sinus arrhythmia during a sustained visual attention challenge compared with the other 3 groups. Infants with prenatal cocaine and opiate exposure had poorer quality of movement and more hypertonicity during the Neonatal Intensive Care Unit Network Neurobehavioral Scale examination. They also had more nonoptimal reflexes and stress/abstinence signs compared with infants with prenatal exposure to cocaine only and those with prenatal exposure to alcohol, tobacco, and marijuana. CONCLUSION: Problems with arousal regulation were identified in infants with prenatal substance exposure. Autonomic dysregulation has been implicated as a mechanism by which these difficulties occur. Our results suggest that infants with prenatal exposure to both cocaine and opiates have the greatest autonomic response to the challenge of a sustained visual attention task, possibly putting these infants at risk for problems associated with physiologic and behavioral regulation, a necessary prerequisite for early learning.

The PhenX Toolkit: get the most from your measures.

The potential for genome-wide association studies to relate phenotypes to specific genetic variation is greatly increased when data can be combined or compared across multiple studies. To facilitate replication and validation across studies, RTI International (Research Triangle Park, North Carolina) and the National Human Genome Research Institute (Bethesda, Maryland) are collaborating on the consensus measures for Phenotypes and eXposures (PhenX) project. The goal of PhenX is to identify 15 high-priority, well-established, and broadly applicable measures for each of 21 research domains. PhenX measures are selected by working groups of domain experts using a consensus process that includes input from the scientific community. The selected measures are then made freely available to the scientific community via the PhenX Toolkit. Thus, the PhenX Toolkit provides the research community with a core set of high-quality, well-established, low-burden measures intended for use in large-scale genomic studies. PhenX measures will have the most impact when included at the experimental design stage. The PhenX Toolkit also includes links to standards and resources in an effort to facilitate data harmonization to legacy data. Broad acceptance and use of PhenX measures will promote cross-study comparisons to increase statistical power for identifying and replicating variants associated with complex diseases and with gene-gene and gene-environment interactions.

PhenX: a toolkit for interdisciplinary genetics research.

PURPOSE OF REVIEW: To highlight standard PhenX (consensus measures for Phenotypes and eXposures) measures for nutrition, dietary supplements, and cardiovascular disease research and to demonstrate how these and other PhenX measures can be used to further interdisciplinary genetics research. RECENT FINDINGS: PhenX addresses the need for standard measures in large-scale genomic research studies by providing investigators with high-priority, well established, low-burden measurement protocols in a web-based toolkit (https://www.phenxtoolkit.org). Cardiovascular and Nutrition and Dietary Supplements are just 2 of 21 research domains and accompanying measures included in the PhenX Toolkit. SUMMARY: Genome-wide association studies (GWAS) provide promise for the identification of genomic markers associated with different disease phenotypes, but require replication to validate results. Cross-study comparisons typically increase statistical power and are required to understand the roles of comorbid conditions and environmental factors in the progression of disease. However, the lack of comparable phenotypic, environmental, and risk factor data forces investigators to infer and to compare metadata rather than directly combining data from different studies. PhenX measures provide a common currency for collecting data, thereby greatly facilitating cross-study analysis and increasing statistical power for identification of associations between genotypes, phenotypes, and exposures.

The PhenX Toolkit pregnancy and birth collections.

PURPOSE: Pregnancy and childbirth are normal conditions, but complications and adverse outcomes are common. Both genetic and environmental factors influence the course of pregnancy. Genetic epidemiologic research into pregnancy outcomes could be strengthened by the use of common measures, which would allow data from different studies to be combined or compared. Here, we introduce perinatal researchers to the PhenX Toolkit and the Collections related to pregnancy and childbirth. METHODS: The Pregnancy and Birth Collections were drawn from measures in the PhenX Tooklit. The lead author selected a list of measures for each Collection, which was reviewed by the remaining authors and revised on the basis of their comments. We chose the measures we thought were most relevant for perinatal research and had been linked most strongly to perinatal outcomes. RESULTS: The Pregnancy and Birth Health Conditions Collection includes 24 measures related to pregnancy and fertility history, maternal complications, and infant complications. The Pregnancy and Birth Outcome Risk Factors Collection includes 43 measures of chemical, medical, psychosocial, and personal factors associated with pregnancy outcomes. CONCLUSIONS: The biological complexity of pregnancy and its sensitivity to environmental and genomic influences suggest that multidisciplinary approaches are needed to generate new insights or practical interventions. To fully exploit new research methods and resources, we encourage the biomedical research community to adopt standard measures to facilitate pooled or meta-analyses.

Physical activity and physical fitness: standardizing assessment with the PhenX Toolkit.

The focus of the PhenX (Phenotypes and eXposures) Toolkit is to provide researchers whose expertise lies outside a particular area with key measures identified by experts for uniform use in large-scale genetic studies and other extensive epidemiologic efforts going forward. The current paper specifically addresses the PhenX Toolkit research domain of physical activity and physical fitness (PA/PF), which are often associated with health outcomes. A Working Group (WG) of content experts completed a 6-month consensus process in which they identified a set of 14 high-priority, low-burden, and scientifically supported measures. During this process, the WG considered self-reported and objective measures that included the latest technology (e.g., accelerometers, pedometers, and heart-rate monitors). They also sought the input of measurement experts and other members of the research community during their deliberations. A majority of the measures include protocols for children (or adolescents), adults, and older adults or are applicable to all ages. Measures from the PA/PF domain and 20 other domains are publicly available and found at the PhenX Toolkit website, www.phenxtoolkit.org. The use of common measures and protocols across large studies enhances the capacity to combine or compare data across studies, benefiting both PA/PF experts and non-experts. Use of these common measures by the research community should increase statistical power and enhance the ability to answer scientific questions that previously might have gone unanswered.

Neurobehavioral disinhibition predicts initiation of substance use in children with prenatal cocaine exposure.

BACKGROUND: In previous work we (Fisher et al., 2011) examined the emergence of neurobehavioral disinhibition (ND) in adolescents with prenatal substance exposure. We computed ND factor scores at three age points (8/9, 11 and 13/14 years) and found that both prenatal substance exposure and early adversity predicted ND. The purpose of the current study was to determine the association between these ND scores and initiation of substance use between ages 8 and 16 in this cohort as early initiation of substance use has been related to later substance use disorders. Our hypothesis was that prenatal cocaine exposure predisposes the child to ND, which, in turn, is associated with initiation of substance use by age 16. METHODS: We studied 386 cocaine exposed and 517 unexposed children followed since birth in a longitudinal study. Five dichotomous variables were computed based on the subject's report of substance use: alcohol only; tobacco only; marijuana only; illicit substances and any substance. RESULTS: Cox proportional hazard regression showed that the 8/9 year ND score was related to initiation of alcohol, tobacco, illicit and any substance use but not marijuana use. The trajectory of ND across the three age periods was related to substance use initiation in all five substance use categories. Prenatal cocaine exposure, although initially related to tobacco, marijuana and illicit substance initiation, was no longer significant with ND scores in the models. CONCLUSION: Prenatal drug exposure appears to be a risk pathway to ND, which by 8/9 years portends substance use initiation.

Sleep problems in children with prenatal substance exposure: the Maternal Lifestyle study.

OBJECTIVE: To examine the associations between sleep problems and prenatal exposure to cocaine, opiates, marijuana, alcohol, and nicotine in children aged 1 month to 12 years. DESIGN: Sleep data were collected by maternal report in a prospective longitudinal follow-up of children participating in the Maternal Lifestyle multisite study. SETTING: Hospital-based research centers in Providence, Rhode Island; Miami, Florida; Detroit, Michigan; and Memphis, Tennessee. PARTICIPANTS: There were 808 participants, 374 exposed to cocaine and/or opiates, and 434 comparison subjects. MAIN EXPOSURE: Prenatal cocaine, opiate, marijuana, alcohol, and/or nicotine exposure. OUTCOME MEASURE: Sleep problems in early, middle, and/or late childhood, assessed as composites of maternal report items. RESULTS: Of the 5 substances, prenatal nicotine exposure was the only unique predictor of sleep problems (B = 0.074, R(2) change = 0.008, P = .01), with adjustment for covariates, including socioeconomic status, marital status, physical abuse, prenatal medical care, and postnatal cigarette smoke exposure. CONCLUSIONS: Prenatal exposure to nicotine was positively associated with children's sleep problems persisting throughout the first 12 years of life. Targeting of this group of children for educational and behavioral efforts to prevent and treat sleep problems is merited given that good sleep may serve as a protective factor for other developmental outcomes.