Development of auditory event-related potentials in infants prenatally exposed to methadone

Opioid receptor signaling throughout ontogeny: Shaping neural and behavioral trajectories

Due to the recent and ongoing opioid crisis in the United States, exposure to opioid drugs in utero is becoming more common, including during medication-assisted therapy used to treat opioid use disorder. As such, careful consideration of opioidergic signaling in utero and beyond, as well as alterations to this signaling via introduction of exogenous opioids, is warranted. This review explores the ontogeny and function of the Mu, Kappa and Delta opioid receptor systems throughout the lifespan, highlighting their importance in guiding neurobehavioral development. We argue for a paradigm shift in conceptualization of opioids as not only contributors within their own system, but also vital regulators of a multitude of downstream neurodevelopmental processes.

Newborn Hearing Screening Results for Infants With Prenatal Opioid Exposure in Southern Appalachia

PURPOSE

Infants prenatally exposed to opioids exhibit withdrawal symptomology that introduce physiological noise and can impact newborn hearing screening results. This study compared the referral rate and physiological noise interpreted by number of trials rejected due to artifact on initial newborn hearing screenings of infants with prenatal opioid exposure (POE) and infants with no opioid exposure (NOE). Furthermore, within the POE group, it examined the relationship of referral rates with severity of withdrawal symptomology, and with maternal and infant risk factors.

METHOD

This study used a retrospective cohort design of electronic medical records from six delivery hospitals in South-Central Appalachia. Newborn hearing screenings were conducted using automated auditory brainstem response (ABR) for 334 infants with POE and 226 infants with NOE. Severity of withdrawal symptomology was measured using the Modified Finnegan Neonatal Abstinence Scoring Tool, which includes observation of behaviors that introduce physiological noise.

RESULTS

There was no significant difference in newborn hearing screening referral rate between infants with POE and infants with NOE. Referral rate was not affected by maternal or infant risk factors. Infants with POE had statistically significant higher artifact (defined as rejected ABR sweeps) than infants with NOE. There was a strong positive correlation between Finnegan scores and artifact but not referral rates. Sensitivity and specificity analysis indicated artifact decreased substantially after Day 4 of life.

CONCLUSIONS

Referral rates of infants with POE were similar to those of infants with NOE. Nevertheless, the withdrawal symptomology of infants with POE introduces physiological noise reflected as artifact on ABR, which can affect efficiency of newborn hearing screenings.

Effect of Neonatal Abstinence Syndrome Treatment Status and Maternal Depressive Symptomatology on Maternal Reports of Infant Behaviors

OBJECTIVE

The objective of this study is to investigate the effects of maternal perinatal depression symptoms and infant treatment status for neonatal abstinence syndrome (NAS) on maternal perceptions of infant regulatory behavior at 6 weeks of age.

METHODS

Mothers and their infants (N = 106; 53 dyads) were recruited from a rural, White cohort in Northeast Maine. Mothers in medication-assisted treatment (methadone) and their infants (n = 35 dyads) were divided based on the infant's NAS pharmacological treatment (n = 20, NAS+ group; n = 15, NAS- group) and compared with a demographically similar, nonexposed comparison group (n = 18 dyads; COMP group). At 6 weeks postpartum, mothers reported their depression symptoms Beck Depression Inventory-2nd Edition) and infant regulatory behaviors [Mother and Baby Scales (MABS)]. Infant neurobehavior was assessed during the same visit using the Neonatal Network Neurobehavioral Scale (NNNS).

RESULTS

Mothers in the NAS+ group showed significantly higher depression scores than the COMP group (p < .05) while the NAS- group did not. Across the sample, mothers with higher depression scores reported higher infant "unsettled-irregularity" MABS scores, regardless of group status. Agreement between maternal reports of infant regulatory behaviors and observer-assessed NNNS summary scares was poor in both the NAS+ and COMP groups.

CONCLUSIONS

Postpartum women in opioid recovery with infants requiring pharmacological intervention for NAS are more at risk for depression which may adversely influence their perceptions of their infants' regulatory profiles. Unique, targeted attachment interventions may be needed for this population.

An intergenerational lifespan perspective on the neuroscience of prenatal substance exposure

Prenatal substance exposure has the potential to impact a variety of domains, with neurobiological effects that last throughout the lifespan. Different substances may impact the brain in both specific and diffuse ways; however, the aberrant neural outcomes following exposure tend to coalesce in three areas: (1) sensorimotor development; (2) arousal, motivation, and reward; and (3) executive functioning, impulse control, and emotion regulation. This manuscript represents a summary and update of a previous review (Morie et al., 2019). We organize this piece by domain and summarize data from published neuroimaging studies that examine the neural correlates of prenatal exposure across developmental stages. While the published neuroimaging literature in the area of prenatal exposure has a range of sampling concerns that may limit generalizability as well as longitudinal prediction, the findings to date do point to domains of interest warranting further study. With this caveat, we synthesize the extant findings to describe ways in which prenatal substance exposure is associated with developmental psychopathology and implicated in potentially aberrant behavioral patterns beginning in infancy and persisting through childhood, adolescence, adulthood, and even parenthood. We also examine how substance abuse may impact parenting behaviors that in turn influences infant and child behavior in ways that may be additive or obscure the direct teratological effects of prenatal exposure. Given this observation, we offer an additional intergenerational lens through which prenatal substance exposure should be studied.

Perinatal Opioid Exposure Results in Persistent Hypoconnectivity of Excitatory Circuits and Reduced Activity Correlations in Mouse Primary Auditory Cortex

Opioid use by pregnant women results in neonatal opioid withdrawal syndrome (NOWS) and lifelong neurobehavioral deficits including language impairments. Animal models of NOWS show impaired performance in a two-tone auditory discrimination task, suggesting abnormalities in sensory processing in the auditory cortex. To investigate the consequences of perinatal opioid exposure on auditory cortex circuits, we administered fentanyl to mouse dams in their drinking water throughout gestation and until litters were weaned at postnatal day (P)21. We then used in vivo two-photon Ca2+ imaging in adult animals of both sexes to investigate how primary auditory cortex (A1) function was altered. Perinatally exposed animals showed fewer sound-responsive neurons in A1, and the remaining sound-responsive cells exhibited lower response amplitudes but normal frequency selectivity and stimulus-specific adaptation (SSA). Populations of nearby layer 2/3 (L2/3) cells in exposed animals showed reduced correlated activity, suggesting a reduction of shared inputs. We then investigated A1 microcircuits to L2/3 cells by performing laser-scanning photostimulation (LSPS) combined with whole-cell patch-clamp recordings from A1 L2/3 cells. L2/3 cells in exposed animals showed functional hypoconnectivity of excitatory circuits of ascending inputs from L4 and L5/6 to L2/3, while inhibitory connections were unchanged, leading to an altered excitatory/inhibitory balance. These results suggest a specific reduction in excitatory ascending interlaminar cortical circuits resulting in decreased activity correlations after fentanyl exposure. We speculate that these changes in cortical circuits contribute to the impaired auditory discrimination ability after perinatal opioid exposure.SIGNIFICANCE STATEMENT This is the first study to investigate the functional effects of perinatal fentanyl exposure on the auditory cortex. Experiments show that perinatal fentanyl exposure results in decreased excitatory functional circuits and altered population activity in primary sensory areas in adult mice. These circuit changes might underlie the observed language and cognitive deficits in infants exposed to opioids.

Consequences of Parental Opioid Exposure on Neurophysiology, Behavior, and Health in the Next Generations

Substance abuse and the ongoing opioid epidemic represents a large societal burden. This review will consider the long-term impact of opioid exposure on future generations. Prenatal, perinatal, and preconception exposure are reviewed with discussion of both maternal and paternal influences. Opioid exposure can have long-lasting effects on reproductive function, gametogenesis, and germline epigenetic programming, which can influence embryogenesis and alter the developmental trajectory of progeny. The potential mechanisms by which preconception maternal and paternal opioid exposure produce deleterious consequences on the health, behavior, and physiology of offspring that have been identified by clinical and animal studies will be discussed. The timing, nature, dosing, and duration of prenatal opioid exposure combined with other important environmental considerations influence the extent to which these manipulations affect parents and their progeny. Epigenetic inheritance refers to the transmission of environmental insults across generations via mechanisms independent of the DNA sequence. This topic will be further explored in the context of prenatal, perinatal, and preconception opioid exposure for both the maternal and paternal lineage.

Neonatal sleep development and early learning in infants with prenatal opioid exposure

The aim of this chapter is to examine the role of sleep and cognition in the context of the cumulative risk model examining samples of at-risk infants and maternal-infant dyads. The cumulative risk model posits that non-optimal developmental outcomes are the result of multiple factors in a child's life including, but not limited to, prenatal teratogenic exposures, premature birth, family socioeconomic status, parenting style and cognitions as well as the focus of this volume, sleep. We highlight poor neonatal sleep as both an outcome of perinatal risk as well as a risk factor to developing attentional and cognitive capabilities during early childhood. Outcomes associated with and contributing to poor sleep and cognition during infancy are examined in relation to other known risks in our clinical population. Implications of this research and recommendations for interventions for this population are provided.

Enduring consequences of perinatal fentanyl exposure in mice

Opioid use by pregnant women is an understudied consequence associated with the opioid epidemic, resulting in a rise in the incidence of neonatal opioid withdrawal syndrome (NOWS) and lifelong neurobehavioral deficits that result from perinatal opioid exposure. There are few preclinical models that accurately recapitulate human perinatal drug exposure and few focus on fentanyl, a potent synthetic opioid that is a leading driver of the opioid epidemic. To investigate the consequences of perinatal opioid exposure, we administered fentanyl to mouse dams in their drinking water throughout gestation and until litters were weaned at postnatal day (PD) 21. Fentanyl-exposed dams delivered smaller litters and had higher litter mortality rates compared with controls. Metrics of maternal care behavior were not affected by the treatment, nor were there differences in dams' weight or liquid consumption throughout gestation and 21 days postpartum. Twenty-four hours after weaning and drug cessation, perinatal fentanyl-exposed mice exhibited signs of spontaneous somatic withdrawal behavior and sex-specific weight fluctuations that normalized in adulthood. At adolescence (PD 35), they displayed elevated anxiety-like behaviors and decreased grooming, assayed in the elevated plus maze and sucrose splash tests. Finally, by adulthood (PD 55), they displayed impaired performance in a two-tone auditory discrimination task. Collectively, our findings suggest that perinatal fentanyl-exposed mice exhibit somatic withdrawal behavior and change into early adulthood reminiscent of humans born with NOWS.

Do infants represent human actions cross-modally? An ERP visual-auditory priming study

Recent findings indicate that 7-months-old infants perceive and represent the sounds inherent to moving human bodies. However, it is not known whether infants integrate auditory and visual information in representations of specific human actions. To address this issue, we used ERPs to investigate infants' neural sensitivity to the correspondence between sounds and images of human actions. In a cross-modal priming paradigm, 7-months-olds were presented with the sounds generated by two types of human body movement, walking and handclapping, after watching the kinematics of those actions in either a congruent or incongruent manner. ERPs recorded from frontal, central and parietal electrodes in response to action sounds indicate that 7-months-old infants perceptually link the visual and auditory cues of human actions. However, at this age these percepts do not seem to be integrated in cognitive multimodal representations of human actions.

Prenatal opioid exposure - Increasing evidence of harm

Prenatal opioid exposure adversely impacts upon fetal growth and places the newborn at risk of neonatal opioid withdrawal. The severity and duration of opioid withdrawal cannot be predicted in the individual baby and may be contributed to by other drugs including benzodiazepines and alcohol as well as cigarette smoking. Mitigating factors include breastfeeding, rooming in and absence of maternal polypharmacy. Less well recognised are a variety of other complications associated with prenatal opioid exposure including epigenetic changes, effects on neurophysiological function and structural alterations to the developing brain. The visual system is significantly affected, with changes to both clinical and electrophysiological function persisting at least to mid-childhood. Longer term neurodevelopmental and behavioural outcomes are confounded by multiple factors including poverty, parent-child interaction and small study numbers, but systematic reviews consistently demonstrate poorer outcomes for those children and young people prenatally exposed to opioids. Crucially, manifestation of neonatal withdrawal is not a prerequisite for important long term problems including behavioural, emotional or motor function disorder, sensory or speech disorder, strabismus and nystagmus. A body of evidence supports an independent adverse effect of prenatal opioid exposure upon fetal brain development, mediated via a systemic neuro-inflammatory process. Children prenatally exposed to opioids should remain under appropriate follow up, at least until school entry, as difficulties may only become apparent in mid-childhood. Future studies of the management of opioid use disorder in pregnancy, including maintenance methadone, must include longer term outcomes for the baby.

Developmental opioid exposures: Neurobiological underpinnings, behavioral impacts, and policy implications

The devastating impact of opioid abuse and dependence on the individual, family, and society are well known but extremely difficult to combat. During pregnancy, opioid drugs and withdrawal also affect fetal brain development and newborn neural functions, in addition to maternal effects. Neonatal Abstinence Syndrome/Neonatal Opioid Withdrawal Syndrome (NAS/NOWS) rates have drastically increased in the US in the past decade. Solutions to this complex problem must be multi-faceted, which would be greatly enhanced by a translational, multidisciplinary understanding. Therefore, this mini-review incorporates biomedical, clinical, and policy aspects of opioid use during pregnancy. We review the known roles for endogenous opioids in mediating circuit formation and function in the developing brain, discuss how exogenous opioid drug use and addiction impact these processes in animal models and humans, and discuss the implications of these data on public policy. We suggest that some current policy initiatives produce unintended harm on both mothers and their children and delineate recommendations for how legislation could better contribute to addiction recovery and increase neural resilience in affected children.

Impact statement

Opioid abuse is a critical epidemic affecting individuals, families, and communities. This mini-review summarizes current literature on the impact of opioid drugs—including prescription pain relievers and illicit opioids—on neurobiological and neurobehavioral development. Using concepts related to the medical model of addiction as a brain disease, we review the public policy implications of these data and identify needs for future investigations.

Prenatal drug exposure from infancy through emerging adulthood: Results from neuroimaging

Prenatal drug exposure may have important repercussions across the lifespan for cognition and behavior. While alcohol is a recognized teratogen, the influences of other substances may also be substantial. The neural underpinnings of the influences of prenatal drug exposure have been examined using longitudinal approaches and multiple imaging techniques. Here we review the existing literature on the neural correlates of prenatal drug exposure. We focused the review on studies that have employed functional neuroimaging and electroencephalography and on substances other than alcohol. We also framed the review through the lens of four developmental life stages (infancy, childhood, adolescence and emerging adulthood). We included papers that have examined any drug use, including tobacco, opiates, cocaine, marijuana, methamphetamines, or polysubstance use. Data suggest that prenatal drug exposure has long-lasting, deleterious influences on cognition and reward processing in infancy and childhood that persist into adolescence and emerging adulthood and may underlie some behavioral tendencies, such as increased externalizing and risk-taking behaviors, seen in these groups.

The Association Between Antenatal Maternal Self-reported Substance Use, Maternal Characteristics, and Obstetrical Variables

BACKGROUND

Substance use disorders during pregnancy are a concern both to the public and medical community, because the negative consequences can be detrimental to both mother and the fetus. The accurate identification of prenatal drug exposure is necessary to determine appropriate medical and psychosocial intervention, and to identify risk factors that may affect outcomes for the mother and her newborn. The prevalence of prenatal drug exposure is very difficult to estimate because of flaws in all methods of identification.

OBJECTIVE

The study is designed to identify risk factors and demographic variables that contribute to nondisclosure of illicit and nonillicit substance use. In addition, this study aims to determine if nondisclosure leads to adverse neonatal outcomes.

STUDY DESIGN

Newborns delivered with a positive meconium or urine toxicology, and/or known maternal exposure to illicit and nonillicit substances, were identified. Maternal records were reviewed for disclosure of substance use during pregnancy at admission for delivery along with other medical and demographic variables. Women with antenatal prescription drug use that may alter toxicology screens were excluded from analysis. Pediatric records were also reviewed to obtain neonatal variables.

RESULTS

One hundred sixty-eight newborns were identified as having prenatal exposure to an illicit or nonillicit substance over the 4-year period. Eighty-six per cent (145/168) of women tested positive or their newborn tested positive for at least 1 illicit substance, and 49% (82/168) tested positive for multiple illicit substances. Fifty-four per cent (91/168) of women did not disclose using at least one illicit drug for which she or her newborn tested positive.With regards to maternal characteristics, there was no statistically significant difference between age (P = 0.958), parity (P = 0.300), or race (P = 0.531), and disclosure or failure to disclose about illicit drug use. However, patients who did not report prenatal illicit drug use (33/82 = 40%) were less likely (P = 0.049) to receive complete prenatal care (defined as 3 or more visits) compared with those who acknowledged their substance use (40/70 = 57%).

CONCLUSION

Substance use disorders during pregnancy are an often underestimated cause of maternal, fetal, and neonatal complications. Limited studies have examined the relationship between maternal characteristics and associated illicit or nonillicit drug use. The absence of correlation between maternal demographics and disclosure of illicit substance use demonstrates the fact that all antepartum patients are at risk for these behaviors. Furthermore, the fact that women who did not disclose their illicit drug use were less likely to seek complete prenatal care reflects the need for physicians to provide a destigmatized healthcare environment, encouraging pregnant women to disclose their substance use so they can be provided with appropriate counseling and treatment.

Association between prenatal opioid exposure, neonatal opioid withdrawal syndrome, and neurodevelopmental and behavioral outcomes at 5-8 months of age

BACKGROUND

While use of prescription opioids and medication assisted therapy (MAT) for opioid use disorder in pregnancy, as well as the incidence of neonatal opioid withdrawal syndrome (NOWS) continue to rise, little is known about outcomes for children with NOWS beyond the newborn period.

METHODS

We examined 1) prenatal MAT exposure vs. unexposed healthy controls [HC]; and 2) treatment for NOWS and NOWS severity on infant neurodevelopmental and behavioral outcomes at 5-8 months of age in 78 maternal-infant pairs from the ENRICH prospective cohort study. Data were obtained from 3 study visits: prenatal, delivery, and neurodevelopmental evaluation at 5-8 months of age. Neurodevelopmental outcomes included the Bayley Scales of Infant Development [BSID-III], caregiver questionnaires (Parenting Stress Index [PSI-SF], Infant Behavior Questionnaire [IBQ-R], Sensory Profile), and the experimental Still-Face Paradigm (SFP).

RESULTS

No differences in the BSID-III, PSI-SF, or IBQ-R scores were observed between MAT and HC groups; however, MAT-exposed and HC infants differed with respect to SFP self-regulation (β = -18.9; p = 0.01) and Sensory Profile sensation seeking (OR = 4.87; 95% CI: 1.55; 15.30) after adjusting for covariates. No significant differences between Treated-for-NOWS vs. not-Treated-for-NOWS were observed. Shorter timing to NOWS treatment initiation was associated with higher Total Stress (β = -9.08; p = 0.035), while longer hospitalization was associated with higher Parent-child dysfunctional interaction (p = 0.018) on PSI-SF.

CONCLUSIONS

Our results provide additional evidence of little-to-no effect of MAT and pharmacological treatment of NOWS on infant neurodevelopmental and behavioral outcomes at 5-8 months of age. However, prolonged hospitalization might increase family psychosocial stress and requires further examination.

A core outcome set for neonatal abstinence syndrome: study protocol for a systematic review, parent interviews and a Delphi survey

BACKGROUND

The prevalence of neonatal abstinence syndrome (NAS) is increasing globally resulting in an increased incidence of adverse neonatal outcomes and health system costs. Evidence regarding the effectiveness of NAS prevention and management strategies is very weak and further research initiatives are critically needed to support meta-analysis and clinical practice guidelines. In NAS research, the choice of outcomes and the use of valid, responsive and feasible measurement instruments are crucial. There is currently no consensus and evidence-based core outcome set (COS) for NAS.

METHODS/DESIGN

The development of the NAS-COS will include five stages led by an international Multidisciplinary Steering Committee: (1) qualitative interviews with parents/families and a systematic review (SR) to identify items for inclusion in a COS. The SR will also identify participants for the Delphi survey, (2) a three-round Delphi survey to gain expert opinion on the importance of health outcomes influencing NAS management decisions, (3), a consensus meeting to finalize the items and definitions with experts and COS users, (4) feasibility and pilot testing, development of the COS and explanatory document and (5) implementation planning.

DISCUSSION

Since standardized outcome measurement and reporting will improve NAS clinical research consistency, efficacy and impact, this COS will reflect the minimum set of health outcomes which should be measured in trials evaluating interventions for preventing or treating NAS.

Use and Misuse of Opioids in Maine: Results From Pharmacists, the Prescription Monitoring, and the Diversion Alert Programs

OBJECTIVE

Although opioids have substantial efficacy for acute pain management, escalation to opioid misuse and abuse is a persistent concern. This report assesses the current status of the opioid epidemic in Maine using three complementary data sets.

METHOD

A representative sample of pharmacists (N = 275) completed an online survey regarding the extent that opioids affected their practice. A county-level analysis of opioid prescriptions (N = 1.22 million) reported to the Maine Prescription Monitoring Program (M-PMP) in 2014 and the agents implicated in arrests as reported to the Maine Diversion Alert Program (DAP, N = 2,700) in 2014/15 also was completed.

RESULTS

A significantly greater number of pharmacists agreed that opioid misuse (85.9%), rather than diversion (76.8%) or access (54.2%), was a concern. Only half (56.2%) reported use of the M-PMP. Opioids were dispensed to 22.4% of residents (37.7% of women in their 80s). This was enough to supply everyone in Maine with a 16.1-day supply. Buprenorphine accounted for almost half of opioid prescriptions to young adults (46.3% women, 49.3% men). Arrests increased by 13.3% from 2014 to 2015, and the proportion of arrests that involved prescription opioids decreased while those involving stimulants and heroin were elevated.

CONCLUSIONS

Pharmacists are very aware of the potential for opioid misuse, but many do not consistently use the M-PMP. There continues to be substantial legitimate use, as well as criminal activity, involving oxycodone and other prescription opioids. Continued vigilance and use of tools like the PMP and DAP are necessary to minimize nonmedical use of opioids in Maine.

Developmental consequences of fetal exposure to drugs: what we know and what we still must learn

Most drugs of abuse easily cross the placenta and can affect fetal brain development. In utero exposures to drugs thus can have long-lasting implications for brain structure and function. These effects on the developing nervous system, before homeostatic regulatory mechanisms are properly calibrated, often differ from their effects on mature systems. In this review, we describe current knowledge on how alcohol, nicotine, cocaine, amphetamine, Ecstasy, and opiates (among other drugs) produce alterations in neurodevelopmental trajectory. We focus both on animal models and available clinical and imaging data from cross-sectional and longitudinal human studies. Early studies of fetal exposures focused on classic teratological methods that are insufficient for revealing more subtle effects that are nevertheless very behaviorally relevant. Modern mechanistic approaches have informed us greatly as to how to potentially ameliorate the induced deficits in brain formation and function, but conclude that better delineation of sensitive periods, dose-response relationships, and long-term longitudinal studies assessing future risk of offspring to exhibit learning disabilities, mental health disorders, and limited neural adaptations are crucial to limit the societal impact of these exposures.