Effects of prenatal substance exposure: altered maturation of visual evoked potentials

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.

Prenatal exposure to opioids: Associations between the caregiving environment and externalizing behaviors

Maternal opioid use during pregnancy is a rapidly growing public health crisis and is associated with a range of adverse developmental outcomes including externalizing behaviors among exposed children. Recent work has highlighted the role of indirect pathways from prenatal opioid exposure to behavioral outcomes through aspects of the caregiving environment, including parenting. This review highlights maternal sensitivity and related aspects of the caregiving environment that may impact the development of externalizing behaviors among children with a history of prenatal exposure to opioids. We conclude by providing suggestions for future directions in research examining development among children with prenatal opioid exposure.

Respiratory and emotional reactivity to ethanol odor in human neonates is dependent upon maternal drinking patterns during pregnancy

BACKGROUND

Beyond the well-known deleterious effects of ethanol defining Fetal Alcohol Spectrum Disorders (FASD), the notion of fetal alcohol programming has gained scientific support. This phenomenon implies early neural plasticity relative to learning mechanisms comprising ethanol´s sensory cues and physiological effects of the drug; among others, its reinforcing properties and its depressant effects upon respiration. In this study, as a function of differential ethanol exposure during gestation, we analyzed neonatal physiological and behavioral responsiveness recruited by the odor of the drug.

METHODS

A factorial design defined by maternal ethanol intake during pregnancy (Low, n = 38; Moderate, n = 18 or High, n = 19) and olfactory stimulation (ethanol odor and/or or a novel scent) served as the basis of the study. Neonatal respiratory and cardiac frequencies, oxygen saturation levels and appetitive or aversive facial expressions, served as dependent variables.

RESULTS

Newborns of High drinkers exhibited significant physiological and behavioral signs indicative of alcohol odor recognition; specifically, respiratory depressions and exacerbated appetitive facial reactions coupled with diminished aversive expressions. Respiratory depressions were not accompanied by heart rate accelerations (cardiorespiratory dysautonomia). According to ROC curve analyses respiratory and behavioral reactivity were predictive of high maternal intake patterns.

CONCLUSIONS

These results validate the notion of human fetal alcohol programming that is detected immediately after birth. The reported early functional signs indicative of relatively high alcohol gestational exposure should broaden our capability of diagnosing FASD and lead to appropriate primary or secondary clinical interventions (Registry of Health Research N.3201- RePIS, Córdoba, Argentina).

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.

An ERP Study of Response Inhibition in the Auditory Domain in Children with Fetal Alcohol Spectrum Disorders

BACKGROUND

Previous event-related potential (ERP) studies of response inhibition in children with fetal alcohol spectrum disorder (FASD) have used a visual Go/NoGo task to study the impact of prenatal alcohol exposure on response inhibition. No studies exist using auditory versions of the task; thus, it is unclear how the deficits observed in visual tasks translate into the auditory domain.

METHODS

This study examined ERPs using an auditory Go/NoGo paradigm in a sample of 35 school-age children-18 with heavy prenatal alcohol exposure and 17 normally developing controls.

RESULTS

Alcohol-exposed children performed as well as controls in terms of inhibiting their responses; however, their reaction times were significantly slower under the Go condition. As in the ERP visual Go/NoGo task previously administered to these children, group differences were seen in early perceptual processing, specifically related to stimulus discrimination, with a decrease in P2 amplitude in the alcohol-exposed group. The control group exhibited greater N2 amplitude in the NoGo compared to the Go condition while the alcohol-exposed group did not, suggesting a group difference in the neural substrates underlying conflict monitoring. The alcohol-exposed group demonstrated longer latency P3 with reduced amplitude, suggesting poorer allocation of attention. The alcohol-exposed group also exhibited a late positive component (LPC) similar to the one observed in the previous visual ERP study. This LPC may indicate compensatory neurophysiological function related to resetting of attentional control networks in preparation for the next trial. None of the ERP outcomes in this study were related to potential confounders which included cognitive and socioeconomic measures as well as ADHD diagnosis.

CONCLUSIONS

The observed ERP group differences point to elements of perceptual and attentional processing likely to be involved in the performance deficits often observed in children with FASD. We also observed changes in ERPs related to conflict monitoring/response inhibition, highlighting fetal alcohol-related effects on how the brain responds when there is need to identify and respond to environmental cues by switching away from a prepotent motor response to an inhibited state.

Visual evoked potential latencies of three-year-old children prenatally exposed to buprenorphine or methadone compared with non-opioid exposed children: The results of a longitudinal study

This study compared the latency of pattern reversal visual evoked potentials (VEP) of 36-month old children exposed to opioid pharmacotherapy in utero to that of a group of non-exposed children. Pregnant women were enrolled as part of an open-label non-randomised flexible dosing longitudinal study. Participants were 21 children whose mothers were treated with buprenorphine- (n=11) or methadone-pharmacotherapy (n=10) during pregnancy, and 15 children not exposed to opioids in pregnancy. One-way between groups analyses of variance (ANOVA) were conducted to test the statistical significance of differences between the mean latencies of the peak response to two different sized checkerboard patterns (48' and 69' of retinal arc). Standard multiple regression analyses were conducted to determine whether there was a significant relationship between group status and VEP latencies after adjusting for the effect of covariates. VEP latencies ranged from 98 to 112 milliseconds (ms) for checks of 48' arc, and from 95 to 113ms for checks of 69' arc. Latencies were comparable across groups. After adjusting for covariates children prenatally exposed to methadone or buprenorphine did not differ significantly from non-opioid exposed children in their responses to either check size. Nor were there any significant differences in VEP latencies between children prenatally exposed to methadone and children prenatally exposed to buprenorphine. Head circumference (HC) was significantly associated with P100 latencies for both check sizes. Data from this controlled, non-randomised study suggest that neither buprenorphine nor methadone appear to have any long-term effects on visual maturity assessed at 36months of age.

Neurobehavioral, neurologic, and neuroimaging characteristics of fetal alcohol spectrum disorders

Alcohol consumption during pregnancy can have deleterious consequences for the fetus, including changes in central nervous system development leading to permanent neurologic alterations and cognitive and behavioral deficits. Individuals affected by prenatal alcohol exposure, including those with and without fetal alcohol syndrome, are identified under the umbrella of fetal alcohol spectrum disorders (FASD). While studies of humans and animal models confirm that even low to moderate levels of exposure can have detrimental effects, critical doses of such exposure have yet to be specified and the most clinically significant and consistent consequences occur following heavy exposure. These consequences are pervasive, devastating, and can result in long-term dysfunction. This chapter summarizes the neurobehavioral, neurologic, and neuroimaging characteristics of FASD, focusing primarily on clinical research of individuals with histories of heavy prenatal alcohol exposure, although studies of lower levels of exposure, particularly prospective, longitudinal studies, will be discussed where relevant.

Primary visual response (M100) delays in adolescents with FASD as measured with MEG

Fetal alcohol spectrum disorders (FASD) are debilitating, with effects of prenatal alcohol exposure persisting into adolescence and adulthood. Complete characterization of FASD is crucial for the development of diagnostic tools and intervention techniques to decrease the high cost to individual families and society of this disorder. In this experiment, we investigated visual system deficits in adolescents (12-21 years) diagnosed with an FASD by measuring the latency of patients' primary visual M100 responses using MEG. We hypothesized that patients with FASD would demonstrate delayed primary visual responses compared to controls. M100 latencies were assessed both for FASD patients and age-matched healthy controls for stimuli presented at the fovea (central stimulus) and at the periphery (peripheral stimuli; left or right of the central stimulus) in a saccade task requiring participants to direct their attention and gaze to these stimuli. Source modeling was performed on visual responses to the central and peripheral stimuli and the latency of the first prominent peak (M100) in the occipital source timecourse was identified. The peak latency of the M100 responses were delayed in FASD patients for both stimulus types (central and peripheral), but the difference in latency of primary visual responses to central vs. peripheral stimuli was significant only in FASD patients, indicating that, while FASD patients' visual systems are impaired in general, this impairment is more pronounced in the periphery. These results suggest that basic sensory deficits in this population may contribute to sensorimotor integration deficits described previously in this disorder.

Prenatal alcohol exposure and educational achievement in children aged 8-9 years

OBJECTIVE

This study examines the relationships between the dose, pattern, and timing of prenatal alcohol exposure and achievement in reading, writing, spelling, and numeracy in children aged 8 to 9 years.

METHODS

Data from a randomly selected, population-based birth cohort of infants born to non-Indigenous women in Western Australia between 1995 and 1997 (n = 4714) (Randomly Ascertained Sample of Children born in Australia's Largest State Study cohort) were linked to the Western Australian Midwives' Notification System and the Western Australian Literacy and Numeracy Assessment statewide education testing program. The records for 86% (n = 4056) of the cohort were successfully linked with education records when the children were aged 8 to 9 years. The associations between prenatal alcohol exposure and achievement of national benchmarks in school numeracy, reading, spelling, and writing tests and nonattendance for the tests was examined. Logistic regression was used to generate adjusted odds ratios (aOR) and 95% confidence intervals (CI), adjusting for potential confounding factors. The referent group included children of mothers who previously drank alcohol but who abstained during pregnancy.

RESULTS

Children were twice as likely not to achieve the benchmark for reading after heavy prenatal alcohol exposure during the first trimester (aOR 2.26; 95% CI 1.10-4.65) and for writing when exposed to occasional binge drinking in late pregnancy (aOR 2.35; 95% CI 1.04-5.43). Low-moderate prenatal alcohol exposure was not associated with academic underachievement.

CONCLUSIONS

The type of learning problems expressed depends on the dose, pattern, and timing of prenatal alcohol exposure.

Maternal supplementation with docosahexaenoic acid during pregnancy does not affect early visual development in the infant: a randomized controlled trial

BACKGROUND

The docosahexaenoic acid (DHA) intake of pregnant women is lower than estimates of the DHA accretion by the fetus, and recommendations were made to increase the DHA intake of pregnant women.

OBJECTIVE

The objective of this study was to determine whether the supplementation of pregnant women with DHA improved the visual acuity of infants at 4 mo.

DESIGN

We conducted a blinded assessment of a subset of healthy, full-term infants born to women enrolled in a double-blind, randomized controlled trial called the DHA for Maternal and Infant Outcomes (DOMInO) trial. Women were randomly assigned to consume DHA-rich fish-oil capsules (≈800 mg DHA/d in the treatment group) or vegetable oil capsules (control group) from midpregnancy to delivery. The primary outcome was the sweep visual evoked potential (VEP) acuity at 4 mo. The VEP latency at 4 mo was a secondary outcome.

RESULTS

Mean (±SD) VEP acuity did not differ between treatment and control groups [treatment group: 8.37 ± 2.11 cycles per degree (cpd), n = 89; control group: 8.55 ± 1.86 cpd, n = 93; P = 0.55]. VEP latencies also did not differ between groups. Irrespective of the group, maternal smoking in pregnancy was independently associated with poorer VEP acuity in the infant.

CONCLUSIONS

DHA supplementation in women with singleton pregnancies does not enhance infant visual acuity in infants at 4 mo of age. Visual acuity in infancy is adversely associated with maternal smoking in pregnancy. This trial was registered at www.anzctr.org.au as ACTRN12606000327583. The DOMInO trial was registered at www.anzctr.org.au as ACTRN12605000569606.

Neurophysiologic and neurobehavioral evidence of beneficial effects of prenatal omega-3 fatty acid intake on memory function at school age

BACKGROUND

The beneficial effects of prenatal and early postnatal intakes of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) on cognitive development during infancy are well recognized. However, few studies have examined the extent to which these benefits continue to be evident in childhood.

OBJECTIVE

The aim of this study was to examine the relation of n-3 PUFAs and seafood-contaminant intake with memory function in school-age children from a fish-eating community.

DESIGN

In a prospective, longitudinal study in Arctic Quebec, we assessed Inuit children (n = 154; mean age: 11.3 y) by using a continuous visual recognition task to measure 2 event-related potential components related to recognition memory processing: the FN400 and the late positive component (LPC). Children were also examined by using 2 well-established neurobehavioral assessments of memory: the Digit span forward from Wechsler Intelligence Scales for Children, 4th edition, and the California Verbal Learning Test-Children's Version.

RESULTS

Repeated-measures analyses of variance revealed that children with higher cord plasma concentrations of docosahexaenoic acid (DHA), which is an important n-3 PUFA, had a shorter FN400 latency and a larger LPC amplitude; and higher plasma DHA concentrations at the time of testing were associated with increased FN400 amplitude. Cord DHA-related effects were observed regardless of seafood-contaminant amounts. Multiple regression analyses also showed positive associations between cord DHA concentrations and performance on neurobehavioral assessments of memory.

CONCLUSION

To our knowledge, this study provides the first neurophysiologic and neurobehavioral evidence of long-term beneficial effects of n-3 PUFA intake in utero on memory function in school-age children.

Functional neuroimaging in the examination of effects of prenatal alcohol exposure

Functional neuroimaging offers the opportunity to understand the effect of prenatal alcohol exposure on the activities of the brain as well as providing a window into the relationship between neural activation and the behavioral outcomes that have been described in affected individuals. Several different methodologies have been used to examine the neurophysiological signal changes associated with different brain functions in prenatally exposed individuals and those diagnosed with fetal alcohol syndrome (FAS) or other fetal alcohol spectrum disorders (FASD). These include electroencephalography (EEG), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI). These studies demonstrate that it is feasible to use these technologies with this clinical population and that the damage to the central nervous system associated with prenatal alcohol exposure has widespread functional implications; however, currently, the literature in these areas is limited and unsystematic. Functional MRI with this clinical population has just begun to explore the implications of prenatal alcohol exposure with the first paper published in 2005. Other methodologies are similarly limited in scope. Nonetheless, these functional neuroimaging studies suggest that prenatal alcohol exposure, or a diagnosis of FAS, may lead to restrictions in neural efficiency or a global decrement in processing resources.

Adolescent ethanol exposure: does it produce long-lasting electrophysiological effects?

This review discusses evidence for long-lasting neurophysiological changes that may occur following exposure to ethanol during adolescent development in animal models. Adolescence is the time that most individuals first experience ethanol exposure, and binge drinking is not uncommon during adolescence. If alcohol exposure is neurotoxic to the developing brain during adolescence, not unlike it is during fetal development, then understanding how ethanol affects the developing adolescent brain becomes a major public health issue. Adolescence is a critical time period when cognitive, emotional, and social maturation occurs and it is likely that ethanol exposure may affect these complex processes. To study the effects of ethanol on adolescent brain, animal models where the dose and time of exposure can be carefully controlled that closely mimic the human condition are needed. The studies reviewed provide evidence that demonstrates that relatively brief exposure to high levels of ethanol, via ethanol vapors, during a period corresponding to parts of adolescence in the rat is sufficient to cause long-lasting changes in functional brain activity. Disturbances in waking electroencephalogram and a reduction in the P3 component of the event-related potential (ERP) have been demonstrated in adult rats that were exposed to ethanol vapor during adolescence. Adolescent ethanol exposure was also found to produce long-lasting reductions in the mean duration of slow-wave sleep (SWS) episodes and the total amount of time spent in SWS, a finding consistent with a premature aging of sleep. Further studies are necessary to confirm these findings, in a range of strains, and to link those findings to the neuroanatomical and neurochemical mechanisms potentially underlying the lasting effects of adolescent ethanol exposure.

Fetal learning about ethanol and later ethanol responsiveness: evidence against "safe" amounts of prenatal exposure

Near-term fetuses of different mammalian species, including humans, exhibit functional sensory and learning capabilities. The neurobiological literature indicates that the unborn organism processes sensory stimuli present in the amniotic fluid, retains this information for considerable amounts of time, and is also capable of associating such stimuli with biologically relevant events. This research has stimulated studies aimed at the analysis of fetal and neonatal learning about ethanol, a topic that constitutes the core of the present review. Ethanol has characteristic sensory (olfactory, taste, and trigeminal) attributes and can exert pharmacologic reinforcing effects. The studies under examination support the hypothesis that low to moderate levels of maternal ethanol intoxication during late pregnancy set the opportunity for fetal learning about ethanol. These levels of prenatal ethanol exposure do not generate evident morphologic or neurobehavioral alterations in the offspring, but they exert a significant impact upon later ethanol-seeking and intake behaviors. Supported by preclinical and clinical findings, this review contributes to strengthening the case for the ability of prenatal ethanol exposure to have effects on the postnatal organism.

Differential effects of acute alcohol on EEG and sedative responses in adolescent and adult Wistar rats

Age-related developmental differences in sensitivity to the acute effects of alcohol may play an important role in the development of alcoholism. The present study was designed to evaluate the acute effects of alcohol on cortical electroencephalogram (EEG) in adolescent (P36) and adult (P78) Wistar rats. Five minutes of EEG was recorded after administration of 0, 0.75 or 1.5 g/kg alcohol. The righting reflex was performed to measure the sedative effects of alcohol (3.5 g/kg) and total sleeping time for each rat. Our results showed that alcohol (1.5 g/kg) increased power in the 1-2 Hz band and decreased the power in the 32-50 Hz band in the parietal cortical region of adolescent rats. Alcohol (1.5 g/kg) also increased stability of the EEG power in the slow-wave frequency bands (2-4 Hz, 4-6 Hz, and 6-8 Hz) of adolescent rats. In the frontal cortex of adult rats, but not in adolescent rats, alcohol (1.5 or 0.75 g/kg) decreased the power in the 16-32 Hz frequency band. Alcohol (1.5 g/kg) differentially increased power in a multiple of slow-wave frequency bands (2-4 Hz and 4-6 Hz) in the parietal cortex of adult rats as compared to adolescent rats. Adolescent rats were shown significantly shorter sleeping time and higher blood alcohol levels after regaining reflex than adult rats. Our results provide additional evidence of age-related differences in the effects of acute alcohol on cortical EEG, sedation and tolerance.

Electroencephalographic correlates of prenatal exposure to alcohol in infants and children: a review of findings and implications for neurocognitive development

In this paper, we reviewed all existing studies using electroencephalography (EEG) in infants and children with known prenatal exposure to alcohol (PEA). The guiding purposes of the review were to determine if (1) EEG is a useful neuroimaging technique for investigating the brain correlates of PEA in infants and children, (2) there are indeed consistent EEG correlates of PEA in literature, and (3) these EEG correlates can be framed within a coherent picture of emerging implications for the study of PEA and its effects. The review confirms that EEG techniques have proven useful in indicating evidence of differential effects of patterns of PEA and timing in early fetal development and impairment of brain maturation in older children. In general, these techniques could be important in functional assessment of the brain of children affected by PEA, especially if used in conjunction with other neuroimaging techniques. The reviewed studies also suggest that although the impact on sensory and cognitive functions may involve extensive neural networks, there are EEG correlates of PEA which may in the future lead to the identification of neurophysiologic markers. A consistent aspect that emerges from the EEG data is that converging evidence from the study of different systems and processes suggests that PEA may almost invariably have consequences for later neurocognitive development.

High-density electroencephalogram monitoring in the neonate

Early diagnosis of neurologic conditions is crucial for successful early intervention; therefore, minimally invasive diagnostic procedures are invaluable during the neonatal period. The clinical usefulness of one such technique, the electroencephalogram (EEG), is well documented. However, the advent of high-density recording systems has extended its application. High-density EEG recording uses a significantly increased number of recordings sites: 128 to 256 electrodes compared with 10 to 30 in standard recording systems. This report describes the benefits of using more electrode sites and highlights the use of related procedures for the assessment of neural integrity across sensory modalities.

Mid- to late gestational morphine exposure does not alter the rewarding properties of morphine in adult male rats

Prenatal exposure to drugs of abuse often leads to physiological and neurobiological abnormalities including decreased brain and body weight, cognitive deficits and behavioral alterations. A handful of studies showed increased vulnerability to drug abuse in prenatally drug-exposed offspring. Our work also demonstrated that prenatal exposure to analgesic doses of morphine during gestation days 11-18 increases mu-opioid receptor density in the nucleus accumbens and central amygdala of adult male rats. Both the nucleus accumbens and central amygdala play important roles in modulating drug-induced reward via the mesolimbic dopaminergic system. Therefore, two types of behavioral paradigms were used to test the hypothesis that the same prenatal morphine exposure would enhance the rewarding effects of morphine, making drug-exposed offspring more vulnerable to abuse this drug in adulthood. All experiments were performed with adult male offspring of saline-injected, morphine-injected or non-injected (control) dams. (1) The unbiased conditioned place preference (CPP) paradigm was used to investigate whether prenatal morphine exposure sensitizes adult male rats to non-contingent morphine reward. These adult animals were conditioned with 0.1, 0.3, 1, 3 or 5 mg/kg morphine. All control, prenatally saline- and morphine-exposed male rats preferred the morphine-paired compartment relative to the saline-paired compartment. However, the magnitude of morphine CPP in adult male rats was not dependent on the conditioning dose of morphine or prenatal morphine exposure. (2) Intravenous morphine self-administration was used to assess the behavioral response to contingent morphine reward. Each rat self-administered one of four doses of morphine (0.3, 1, 2 or 3 mg/kg/infusion). Morphine self-administration was not altered in prenatally morphine-exposed adult male offspring. Control males self-administered significantly less morphine at the lowest dose of morphine than both prenatally saline- and morphine-exposed males. Although our data show that prenatal exposure to an analgesic dose of morphine during the time of opioid receptor appearance does not enhance morphine CPP or self-administration, they do not exclude the possibility that this prenatal morphine exposure enhances the rewarding properties of other drugs of abuse.

Neurophysiologic consequences of neonatal ethanol exposure in the rat

Many of the neurotoxic and neurobehavioral consequences of neonatal ethanol exposure in the rat have been characterized. However, in few studies has adult neurophysiologic function been assessed in rats exposed to ethanol during this key developmental period. In the current study, the effects of neonatal ethanol exposure on adult electroencephalographic (EEG) activity and auditory event-related potentials (ERPs) were examined in the rat. Male Sprague-Dawley rats were exposed to ethanol at 6.0 g/kg/day between postnatal days 4 through 9 by using an artificial-rearing procedure. Two control groups were used: a suckle control (SC) group and a gastrostomized control (GC) group. After reaching adulthood (i.e., at 3.5-4 months old), recording electrodes were implanted into the brain of each rat, so that EEG activity and auditory ERPs from the cortex and hippocampus could be assessed. Rats exposed to ethanol during the neonatal period were hyperactive as adults. Assessment of the EEG activity revealed that ethanol exposure increased peak frequency in the frontal cortical and parietal cortical 16-32 Hz frequency bands. Assessment of ERPs revealed that parietal cortical N1 amplitude was reduced in ethanol-exposed rats. Furthermore, parietal cortical N1 latency was increased in the GC group. These findings demonstrate that enhanced motor activity in rats exposed to ethanol during neonatal development occurs in combination with EEG indices of enhanced cortical and hippocampal arousal. Furthermore, a deficiency in cortical N1 amplitude indicates adult rats may have attention deficits. Overall, these results indicate that neonatal ethanol exposure has enduring neurobehavioral consequences, which persist into adulthood. This neurobehavioral profile in the rat is consistent with clinical observations of attention deficits and hyperactivity in children exposed to ethanol during prenatal development.

Follow-up data their use in evidence-based decision-making

Experience with certain perinatal interventions, such as supplemental oxygen and dexamethasone, leads to the conclusion that follow-up data are needed to be well informed about the safety of certain perinatal interventions. Experience with indomethacin suggests that follow-up data also are regarded by some clinicians as a necessary aspect of evidence about effectiveness. Ideally, clinical trials of perinatal interventions might involve collection of data about neonatal predictors of outcome (such as a neuroimaging study and a standardized neurologic assessment); several developmental and neurologic assessments before school entry; a comprehensive evaluation of the child's cognitive function, behavioral competencies, and academic performance at 7 to 8 years of age; serial detailed assessments of the family psychosocial functioning; and an inventory of resources available for the child. Many clinical trials have not included follow-up after the neonatal period, and in such cases information about the effect of the intervention on participants' HRQL is incomplete. The approach taken in several recent trials, in which the outcome of interest is neurodevelopmental outcome at 18 months, attempts to strike a balance between a theoretical ideal (a comprehensive, longitudinal follow-up through school age) and a follow-up regimen that is not prohibitively expensive. Such trials include follow-up during the first 1 to 3 years of life, when major disabilities can be identified reliably, thereby providing moderately informative data about participants' eventual quality of life, related to the presence or absence of major disability. If, however, there is reason to suspect that the intervention has effects on the developing brain, follow-up after school entry may provide additional evidence pertinent to the risks and benefits of the intervention.

Reciprocal obligations: managing policy responses to prenatal substance exposure

Substance use during pregnancy poses substantial risks to the developing fetus and continues to generate considerable policy debate. Public policy responses to prenatal substance exposure (PSE) have varied depending in part on whether the substances in question are licit (e.g., tobacco and alcohol) or illicit (e.g., cocaine and heroin). The policy responses also have ranged from warning labels on the dangers to the developing fetus of using alcohol, to treating a pregnant woman's illicit substance use as child abuse. The most controversial case was Cornelia Whitner's criminal conviction in South Carolina for PSE after her newborn baby tested positive for cocaine metabolites. Although the conviction was upheld by the South Carolina Supreme Court, it is, to date, an isolated example (Whitner v. State of South Carolina, 492 S.E.2d 777 [S.C. 1997], cert denied, 523 U.S. 1145 [1998], but see Ferguson v. City of Charleston, 532 U.S. 67 [2001], and Ferguson v. City of Charleston, 308 F.3d 380 [4th Cir. 2002], ruling that PSE detection policies require the woman's informed consent).

Marijuana use among adolescents

More than half of US adolescents will experiment with marijuana. Of those who try marijuana more than once, approximately one third will subsequently use marijuana regularly, although most will have stopped by their late 20s. Although genetic predisposition plays the most important role in determining who will develop dependence, environmental factors influence who will initiate marijuana use. One of the challenges for prevention and treatment programs is that the immediate adverse effects of marijuana use are not extreme, and many adolescents have difficulty in making decisions based on future risks. Therefore, the consequences of leaving school early, having unprotected sex, and driving while intoxicated are often insufficient to deter adolescents from using marijuana. Thus, it is not surprising that current prevention and treatment programs have had limited success in decreasing the rates of initiation and regular use of marijuana among adolescents. However, the accumulation of data about marijuana use in adolescents has the potential to enable the development of more effective prevention and treatment programs.

Periadolescent alcohol exposure has lasting effects on adult neurophysiological function in rats

Most individuals have their first experience with ethanol (EtOH) consumption as adolescents. Episodes of high EtOH drinking, lasting from hours to days (i.e. binges), are not uncommon. Thus, adolescent EtOH drinking has become a significant health concern due to the possible protracted effects of high doses of EtOH on behavior and the developing brain. This study assessed the effects of brief high levels of EtOH during periadolescence on subsequent behavior and electrophysiology in adult rats. Male Sprague-Dawley rats were exposed to EtOH vapor for 5 days (i.e. postnatal days 35-40) or 10 days (i.e. postnatal days 30-40) for 12 h/day. Locomotor activity, EEG activity, and event-related potentials (ERPs) were then assessed at 1 and 6-7 weeks post EtOH exposure. Significant differences in locomotor activity were not observed at 1 week or 6-7 weeks post-ethanol exposure. However, EtOH exposure did have long-term electrophysiological effects. EtOH exposure increased the frequency of the EEG in the 1-2 Hz range in the parietal cortex and the 16-32 Hz range in the hippocampus. EtOH exposure also increased hippocampal N2 amplitude, decreased hippocampal P3 amplitude, and decreased cortical and hippocampal P2 amplitudes. While these findings are generally similar to those reported following long-term ethanol exposure during adulthood, alcohol exposure during adolescence appears to produce more robust hippocampal effects following shorter periods of exposure. In addition, these data indicate that, in the absence of overt behavioral differences, there are long-lasting changes in the functional brain activity of adult rats briefly exposed to high levels of EtOH during the periadolescent period.

Differential responsiveness to alcohol odor in human neonates: effects of maternal consumption during gestation

Previous human and animal studies have shown that specific memories arise during prenatal life as a function of fetal processing of chemosensory stimuli present in the amniotic fluid. Furthermore, the animal literature indicates that fetal exposure to alcohol modifies subsequent neonatal and infantile responsiveness toward the sensory attributes of the drug. The main goal of the present study was to analyze whether differential maternal alcohol consumption during pregnancy affects neonatal reactivity to ethanol odor. To achieve this goal, an initial experiment examined how healthy human neonates respond to olfactory stimuli. In this first experiment, newborns (postpartum age: 24-48 h) were evaluated in terms of motor responsiveness elicited by repetitive stimulation with either alcohol or lemon odors. Infants exhibited a marked increase in duration of overall body and head and facial activity when the odorants were first presented. In four successive trials, behavioral responsiveness progressively declined until reaching baseline values. The introduction of a novel odorant served to dishabituate the motor responses under analysis. In the second experiment newborn's reactivity to the mentioned odorants was evaluated as a function of maternal self-reported patterns of consumption of alcohol during gestation. Mothers were classified as frequent or infrequent drinkers. Babies born to frequent drinkers exhibited heightened reactivity toward ethanol odor when compared to newborns delivered by infrequent drinkers. No differences emerged when comparing the responses of both groups of infants elicited by a non-ethanol stimulus such as lemon. The results coupled with prior human and animal research suggest the possibility of intrauterine experience with alcohol odor that yields a sensory memory likely to be retrieved immediately after birth.

Two prenatal alcohol use screening instruments compared with a physiologic measure

OBJECTIVE

To compare two prenatal alcohol use screening instruments with a physiologic measure of prenatal alcohol use.

DESIGN

Retrospective comparison of the Prenatal Alcohol Use Interview (PAUI) and the ACOG Antepartum Record with CDTect.

SETTING

An inner-city, high-volume, prenatal clinic.

PARTICIPANTS

Fifty-six women selected and enrolled at their first prenatal visits.

MAIN OUTCOME MEASURE

An assessment of relative sensitivity and specificity of two prenatal alcohol use screening instruments.

RESULTS

Women identified as Drinkers by the CDTect were more likely to be identified as Drinkers by the PAUI (59%) than by the ACOG Antepartum Record (19%). Also, the PAUI had a lower false negative rate (41%) than the ACOG record (80%). That is, the PAUI was less likely to identify as Quitters women the CDTect identified as Drinkers than was the ACOG record.

CONCLUSION

The PAUI is a more sensitive screen than the ACOG record and should be the instrument preferred for screening prenatal alcohol use.

Effect of enriched environment rearing on impairments in cortical excitability and plasticity after prenatal alcohol exposure

The daily ingestion of alcohol by pregnant mammals exposes the fetal brain to varying levels of alcohol through the placental circulation. Here we focus on the lingering impact on cortical function of 6.5% alcohol administered in a liquid diet to pregnant rats throughout gestation, followed by 3 alcohol-free months before brain function was analyzed in the offspring. Both spontaneous activity of the neurons in the barrel cortex and the level of response to test stimuli applied to the whiskers remained reduced by >75% after alcohol exposure. Whisker pairing, a type of cortical plasticity induced by trimming all but two whiskers in adult rats, occurred in <1 d in controls, but required 14 d to reach significance after alcohol exposure. These long-term neuronal deficits are present in all layers of cortex and affect neurons with both fast and slow action potentials. Plasticity is first seen in the total sample of neurons at 14 d; however, by 7 d, neurons in layer II/III already show plasticity, with no change in layer IV neurons, and a reverse shift occurs toward the inactive whisker in layer V neurons. Analysis of NMDA receptor subunits shows a persistent, approximately 30-50% reduction of NR1, NR2A, and NR2B subunits at postnatal day 90 in the barrel field cortex. Exposing the prenatal alcohol-exposed rats to enriched rearing conditions significantly improves all measured cortical functions but does not restore normal values. The results predict that combinations of interventions will be necessary to completely restore cortical function after exposure of the fetal brain to alcohol.