Fifty Years of Research on Prenatal Substances: Lessons Learned for the Opioid Epidemic

Beyond a simple cause and effect relationship: Exploring the long-term outcomes of children prenatally exposed to opioids and other substances

The long-term outcomes of children exposed to opioids and other substances in utero, specifically those diagnosed with Neonatal Abstinence Syndrome (NAS), present a complex interaction of different factors. First, NAS and its clinical presentation will be defined, then summarized will be an overview of NAS prevalence, recent trends, and significance of NAS in the context of the rising synthetic opioid and polysubstance use. Highlighted will also be the identified risk factors for NAS, especially regarding the role of environmental and psychosocial stressors during pregnancy. Finally, reviewed will be the existing NAS literature, including its gaps and limitations, and suggested recommendations for future research and policy considerations for improving care for children and families impacted by NAS.

Independent and Interactive Impacts of Prenatal Exposure to Legal Substances and Childhood Trauma on Emotion Processing in Pre-Adolescents: Preliminary Findings From the ABCD Study

Objective

This paper investigated the effects of prenatal drug exposure (PDE), childhood trauma (CT), and their interactions on the neurobiological markers for emotion processing.

Method

Here, in a non-clinical sample of pre-adolescents (9-10 years of age) from the Adolescent Brain Cognitive Development (ABCD) Study (N = 6,146), we investigate the impact of PDE to commonly used substances (ie, alcohol, cigarettes, and marijuana), CT, and their interaction on emotion processing. From the Emotional N-back functional magnetic resonance imaging task data, we selected 26 regions of interests, previously implicated in emotion processing, and conducted separate linear mixed models (108 total) and accounted for available environmental risk factors.

Results

PDE was associated with reductions in response bias related to the processing of fearful compared to happy faces in widespread cortical regions (including the superior frontal and fusiform gyri and the inferior parietal lobule). Reduced response bias in the superior frontal gyrus emerged as PDE driven and was present regardless of CT status, but correlated with several items on the Child Behavior Checklist only in those children with both PDE and CT. The lower response bias of the left inferior parietal lobule, on the other hand, was observed only in children with both PDE and CT, and correlated with internalizing and externalizing behaviors.

Conclusion

The study's results support the diathesis-stress model, and suggest that PDE may confer vulnerability to the effects of later CT through altered neurodevelopment. Children experiencing these "double-hit" conditions may represent at-risk individuals who could benefit from early interventions to mitigate the onset of psychopathology. Because of limitations in the way that PDE was reported in the ABCD Study, including lack of severity measures and retrospective reporting, results are not sufficient for making recommendations or dictating policy for pregnant persons. Nevertheless, this study is a necessary first step in examining the interactive effects of prenatal and early-life exposures, as well as many aspects of the sociodemographic and psychological environment.

The HEALthy Brain and Child Development Study (HBCD): NIH collaboration to understand the impacts of prenatal and early life experiences on brain development

The human brain undergoes rapid development during the first years of life. Beginning in utero, a wide array of biological, social, and environmental factors can have lasting impacts on brain structure and function. To understand how prenatal and early life experiences alter neurodevelopmental trajectories and shape health outcomes, several NIH Institutes, Centers, and Offices collaborated to support and launch the HEALthy Brain and Child Development (HBCD) Study. The HBCD Study is a multi-site prospective longitudinal cohort study, that will examine human brain, cognitive, behavioral, social, and emotional development beginning prenatally and planned through early childhood. Influenced by the success of the ongoing Adolescent Brain Cognitive DevelopmentSM Study (ABCD Study®) and in partnership with the NIH Helping to End Addiction Long-term® Initiative, or NIH HEAL Initiative®, the HBCD Study aims to establish a diverse cohort of over 7000 pregnant participants to understand how early life experiences, including prenatal exposure to addictive substances and adverse social environments as well as their interactions with an individual's genes, can affect neurodevelopmental trajectories and outcomes. Knowledge gained from the HBCD Study will help identify targets for early interventions and inform policies that promote resilience and mitigate the neurodevelopmental effects of adverse childhood experiences and environments.

Evaluation of histological and ultrastructural changes provoked by prenatal tramadol on postnatal cortical cerebellar neuronal development in rats: possible implication of Ki67, GFAP and MicroRNA-7/P53 signalling trajectories

Tramadol is a novel centrally acting analgesic. Despite, its implementation during pregnancy may impair neuronal survival and synaptic development in neonatal cerebella. The current investigation assessed the histological and ultrastructural alterations in postnatal cortical cerebellar neuronal development induced by prenatal tramadol. 30 offsprings were divided to control group I: fifteen pups born to mothers given saline from D10 till D21 of gestation. Tramadol-treated group II: fifteen pups born to mothers received tramadol HCL (50 mg/kg/day) from D10 till D21 of gestation. Pups were categorized into three subgroups (a, b, and c) and offered for sacrifice on the seventh, fourteenth and twenty-first post-natal days. Light microscopic examination revealed the overcrowding and signs of red degeneration affecting purkinje cell layer. Neurodegenerative signs of both purkinje and granule cell neurons were also confirmed by TEM in form of chromatin condensation, dilated Golgi channels, disrupted endoplasmic reticulum, marked infolding of the nuclear envelope and decrease in granule cell precursors. In addition, the astrocytic processes and terminal nerve axons appeared with different degrees of demyelination and decreased number of oligodendrocytes and degenerated mitochondria. Furthermore, group II exhibited an increase in P53 immune expression. The area percentage of apoptotic cells detected by TUNEL assay was significantly increased. Besides to the significant decrease of Ki67 immunoreactivity in the stem neuronal cell progenitors. Quantitative PCR results showed a significant decline in micro RNA7 gene expression in tramadol treated groups resulting in affection of multiple target genes in P53 signaling pathways, improper cortical size and defect in neuronal development.

Infant Behaviors, Prenatal Cocaine Exposure, and Adult Intelligence

Importance

Linking prenatal drug exposures to both infant behavior and adult cognitive outcomes may improve early interventions.

Objective

To assess whether neonatal physical, neurobehavioral, and infant cognitive measures mediate the association between prenatal cocaine exposure (PCE) and adult perceptual reasoning IQ.

Design, Setting, and Participants

This study used data from a longitudinal, prospective birth cohort study with follow-up from 1994 to 2018 until offspring were 21 years post partum. A total of 384 (196 PCE and 188 not exposed to cocaine [NCE]) infants and mothers were screened for cocaine or polydrug use. Structural equation modeling was performed from June to November 2023.

Exposures

Prenatal exposures to cocaine, alcohol, marijuana, and tobacco assessed through urine and meconium analyses and maternal self-report.

Main Outcomes and Measures

Head circumference, neurobehavioral assessment, Bayley Scales of Infant Development, Fagan Test of Infant Intelligence score, Wechsler Perceptual Reasoning IQ, Home Observation for Measurement of the Environment (HOME) score, and blood lead level.

Results

Among the 384 mothers in the study, the mean (SD) age at delivery was 27.7 (5.3) years (range, 18-41 years), 375 of 383 received public assistance (97.9%) and 336 were unmarried (87.5%). Birth head circumference (standardized estimate for specific path association, -0.05, SE = 0.02; P = .02) and 1-year Bayley Mental Development Index (MDI) (standardized estimate for total of the specific path association, -0.05, SE = 0.02; P = .03) mediated the association of PCE with Wechsler Perceptual Reasoning IQ, controlling for HOME score and other substance exposures. Abnormal results on the neurobehavioral assessment were associated with birth head circumference (β = -0.20, SE = 0.08; P = .01). Bayley Psychomotor Index (β = 0.39, SE = 0.05; P < .001) and Fagan Test of Infant Intelligence score (β = 0.16, SE = 0.06; P = .01) at 6.5 months correlated with MDI at 12 months.

Conclusions and Relevance

In this cohort study, a negative association of PCE with adult perceptual reasoning IQ was mediated by early physical and behavioral differences, after controlling for other drug and environmental factors. Development of infant behavioral assessments to identify sequelae of prenatal teratogens early in life may improve long-term outcomes and public health awareness.

The association of prenatal cocaine exposure with expressive and receptive language skills, phonological processing and reading ability at age 17

OBJECTIVE

Prenatal cocaine exposure (PCE) has been associated with small but significant effects on language development in childhood and early adolescence. This study examined whether this association persists into later adolescence and what relationship language skills may have with reading proficiency in this population.

METHODS

Enrolled were 338 (167 with PCE, 171 with NCE or no cocaine exposure) 17-year-olds recruited at birth who, together with their current caregiver, were seen as part of a 17-year follow-up. Participants were given assessments of reading achievement (WIAT-III), receptive and expressive language (CELF-IV), and phonological processing (CTOPP). Relationships between PCE status and language outcomes were modeled using multiple linear regression controlling for environmental and caregiver factors, and other prenatal substance exposures.

RESULTS

Adolescents with PCE scored lower in areas of phonological processing and reading related skills compared to adolescents with NCE. PCE by sex interactions were identified on language, memory and spoken language comprehension, with lower scores for girls with PCE compared to girls with NCE.

CONCLUSION

These findings suggest the persistence of PCE's relationship with phonological awareness well into adolescence. PCE was also associated with lower scores on measures of skills related to reading ability, which may be a manifestation of the observed deficits in phonological processing.

Prenatal opioid exposure inhibits microglial sculpting of the dopamine system selectively in adolescent male offspring

The current opioid epidemic has dramatically increased the number of children who are prenatally exposed to opioids, including oxycodone. A number of social and cognitive abnormalities have been documented in these children as they reach young adulthood. However, little is known about the mechanisms underlying developmental effects of prenatal opioid exposure. Microglia, the resident immune cells of the brain, respond to acute opioid exposure in adulthood. Moreover, microglia are known to sculpt neural circuits during typical development. Indeed, we recently found that microglial phagocytosis of dopamine D1 receptors (D1R) in the nucleus accumbens (NAc) is required for the natural developmental decline in NAc-D1R that occurs between adolescence and adulthood in rats. This microglial pruning occurs only in males, and is required for the normal developmental trajectory of social play behavior. However, virtually nothing is known as to whether this developmental program is altered by prenatal exposure to opioids. Here, we show in rats that maternal oxycodone self-administration during pregnancy leads to reduced adolescent microglial phagocytosis of D1R and subsequently higher D1R density within the NAc in adult male, but not female, offspring. Finally, we show prenatal and adult behavioral deficits in opioid-exposed offspring, including impaired extinction of oxycodone-conditioned place preference in males. This work demonstrates for the first time that microglia play a key role in translating prenatal opioid exposure to changes in neural systems and behavior.

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.

Psychotropic drug abuse in pregnancy and its impact on child neurodevelopment: A review

Substance abuse by women of child-bearing age and fetal in utero drug exposure has increased in the number of infants born with health issues. Prenatal exposure to psychoactive substances can lead to neurological and neurodevelopmental deficits later in life. Useful data concerning the effects of psychoactive drugs on fetal neurodevelopmental status are sparse. Understanding the neurodevelopmental consequences of prenatally drug-exposed children has become a pressing global concern. The aim of this review is to gather current evidence and information on neurodevelopmental outcomes of in utero drug exposure. A literature search was performed on the PubMed, Scopus, and Google Scholar databases using the terms “psychotropic drugs”, “neurodevelopmental consequences”, “prenatal drug exposure”, and “pregnancy”. Available studies on in utero drug exposure were reviewed and found to support the idea that some degree of health issues are present in fetuses and children. Different psychoactive substances have profound neurodevelopmental consequences, such as structural brain changes, poor attention span, Down syndrome, attention deficit hyperactivity disorder, autism spectrum disorder, imbalances in neurotransmitter levels, and many structural deficits. The pervasive use of psychoactive drugs in women of child-bearing age is an important health concern. Further scientific efforts are needed to investigate the effect of prenatal exposure to psychoactive drugs on children.

Adapting an Evidence-Based Home Visiting Intervention for Mothers With Opioid Dependence: Modified Attachment and Biobehavioral Catch-up

Infants born to mothers who are dependent on opioids often have difficulty regulating behavior and physiology at birth. Without sensitive maternal care, these infants are at risk for ongoing problems with self-regulation. Mothers who are dependent on opioids may experience challenges related to their substance use (e.g., unsupportive and/or risky environment, impulse control and reward system problems) that increase the likelihood of insensitive parenting in the absence of effective intervention. In this paper, we describe a home-visiting intervention we have adapted to enhance sensitive, responsive caregiving tailored to the specific needs of mothers with opioid dependence. The original intervention, Attachment and Biobehavioral Catch-up (ABC), was designed for mothers of infants aged 6-24 months who were exposed to early adversity. ABC has been shown to enhance sensitive parenting as well as children's behavioral and biological functioning, with positive outcomes extending into at least middle childhood. Mothers who are opioid dependent need earlier support than provided by ABC because opioid-exposed infants are often vulnerable at birth. The adapted intervention (modified ABC or mABC) includes one prenatal session and one early postnatal session, followed by 10 sessions every 2-3 weeks. In the initial two sessions in particular, mothers are helped to anticipate the challenges of caring for a baby who may be difficult to soothe while nonetheless providing sensitive care. mABC is intended to help mothers see the importance of responding sensitively so as to help infants overcome the developmental risks associated with opioid exposure. Additionally, mABC is structured to support mothers with the challenges of early parenting, especially if the mother herself was not parented sensitively. Throughout, the focus is on helping the mother nurture the distressed infant, attend to the infant's signals, and avoid behaving in overstimulating or intrusive ways. Case examples are presented that highlight both the challenges of working with this population as well as the gains made by mothers.

Infant neurodevelopmental outcomes of prenatal opioid exposure and polysubstance use

BACKGROUND

Prenatal opioid exposure has been linked to adverse birth outcomes and delays in infant development. Existing literature is limited by a simple group-differences approach as well as inadequate controls for sociodemographic factors and polysubstance exposure co-occurring with prenatal opioid use.

METHOD

The current study assessed cumulative opioid exposure (duration of prescribed and illicit opioid use) as a predictor of infant birth outcomes and mother-reported developmental status at three and six months of age, controlling for polysubstance exposure. Participants were predominantly low-income pregnant and peripartum women, oversampled for mothers receiving medication-assisted treatment (MAT) for opioid use disorder. Prenatal opioid and non-opioid substance use were reported by mothers using a Timeline Follow-Back Interview completed during the third trimester and updated postnatally (infant age six months).

RESULTS

Developmental scores were in the normal range. However, total opioid exposure was positively related to premature birth and inversely related to mother-reported developmental status in specific domains. Associations with three-month fine motor skills and six-month communication skills were robust to controls for polysubstance exposure and sociodemographic covariates.

CONCLUSIONS

Results suggest unique effects of prenatal opioid exposure on the early development of fine motor and communication skills. Similar findings were obtained for prescribed and illicit opioid use, underscoring developmental risks of both MAT and untreated substance use. Exploratory analyses investigating type and timing of MAT suggest directions for future research.