Level of prenatal cocaine exposure and 48-month IQ: importance of preschool enrichment

Associations between Prenatal and Postnatal Exposure to Cannabis with Cognition and Behavior at Age 5 Years: The Healthy Start Study

BACKGROUND

Prenatal exposure to cannabis may influence childhood cognition and behavior, but the epidemiologic evidence is mixed. Even less is known about the potential impact of secondhand exposure to cannabis during early childhood.

OBJECTIVE

This study sought to assess whether prenatal and/or postnatal exposure to cannabis was associated with childhood cognition and behavior.

STUDY DESIGN

This sub-study included a convenience sample of 81 mother-child pairs from a Colorado-based cohort. Seven common cannabinoids (including delta 9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD)) and their metabolites were measured in maternal urine collected mid-gestation and child urine collected at age 5 years. Prenatal and postnatal exposure to cannabis was dichotomized as exposed (detection of any cannabinoid) and not exposed. Generalized linear models examined the associations between prenatal or postnatal exposure to cannabis with the NIH Toolbox and Child Behavior Checklist T-scores at age 5 years.

RESULTS

In this study, 7% (n = 6) of the children had prenatal exposure to cannabis and 12% (n = 10) had postnatal exposure to cannabis, with two children experiencing this exposure at both time points. The most common cannabinoid detected in pregnancy was Δ9-THC, whereas the most common cannabinoid detected in childhood was CBD. Postnatal exposure to cannabis was associated with more aggressive behavior (β: 3.2; 95% CI: 0.5, 5.9), attention deficit/hyperactivity problems (β: 8.0; 95% CI: 2.2, 13.7), and oppositional/defiant behaviors (β: 3.2; 95% CI: 0.2, 6.3), as well as less cognitive flexibility (β: -15.6; 95% CI: -30.0, -1.2) and weaker receptive language (β: -9.7; 95% CI: -19.2, -0.3). By contrast, prenatal exposure to cannabis was associated with fewer internalizing behaviors (mean difference: -10.2; 95% CI: -20.3, -0.2) and fewer somatic complaints (mean difference: -5.2, 95% CI: -9.8, -0.6).

CONCLUSIONS

Our study suggests that postnatal exposure to cannabis is associated with more behavioral and cognitive problems among 5-year-old children, independent of prenatal and postnatal exposure to tobacco. The potential risks of cannabis use (including smoking and vaping) during pregnancy and around young children should be more widely communicated to parents.

A Meta-Analysis of Stressors from the Total Environment Associated with Children's General Cognitive Ability

General cognitive ability, often referred to as ‘general intelligence’, comprises a variety of correlated abilities. Childhood general cognitive ability is a well-studied area of research and can be used to predict social outcomes and perceived success. Early life stage (e.g., prenatal, postnatal, toddler) exposures to stressors (i.e., chemical and non-chemical stressors from the total (built, natural, social) environment) can impact the development of childhood cognitive ability. Building from our systematic scoping review (Ruiz et al., 2016), we conducted a meta-analysis to evaluate more than 100 stressors related to cognitive development. Our meta-analysis identified 23 stressors with a significant increase in their likelihood to influence childhood cognitive ability by 10% or more, and 80 stressors were observed to have a statistically significant effect on cognitive ability. Stressors most impactful to cognition during the prenatal period were related to maternal health and the mother’s ability to access information relevant to a healthy pregnancy (e.g., diet, lifestyle). Stressors most impactful to cognition during the early childhood period were dietary nutrients (infancy), quality of social interaction (toddler), and exposure to toxic substances (throughout early childhood). In conducting this analysis, we examined the relative impact of real-world exposures on cognitive development to attempt to understand the inter-relationships between exposures to both chemical and non-chemical stressors and early developmental life stages. Our findings suggest that the stressors observed to be the most influential to childhood cognitive ability are not permanent and can be broadly categorized as activities/behaviors which can be modified to improve childhood cognition. This meta-analysis supports the idea that there are complex relationships between a child’s total environment and early cognitive development.

Totality of the Evidence Suggests Prenatal Cannabis Exposure Does Not Lead to Cognitive Impairments: A Systematic and Critical Review

Background: Despite limited data demonstrating pronounced negative effects of prenatal cannabis exposure, popular opinion and public policies still reflect the belief that cannabis is fetotoxic.

Methods: This article provides a critical review of results from longitudinal studies examining the impact of prenatal cannabis exposure on multiple domains of cognitive functioning in individuals aged 0 to 22 years. A literature search was conducted through PsycINFO, PubMed, and Google Scholar. Articles were included if they examined the cognitive performance of offspring exposed to cannabis in utero.

Results: An examination of the total number of statistical comparisons (n = 1,001) between groups of participants that were exposed to cannabis prenatally and non-exposed controls revealed that those exposed performed differently on a minority of cognitive outcomes (worse on <3.5 percent and better in <1 percent). The clinical significance of these findings appears to be limited because cognitive performance scores of cannabis-exposed groups overwhelmingly fell within the normal range when compared against normative data adjusted for age and education.

Conclusions: The current evidence does not suggest that prenatal cannabis exposure alone is associated with clinically significant cognitive functioning impairments.

Parental Substance Abuse As an Early Traumatic Event. Preliminary Findings on Neuropsychological and Personality Functioning in Young Drug Addicts Exposed to Drugs Early

Parental substance use is a major risk factor for child development, heightening the risk of drug problems in adolescence and young adulthood, and exposing offspring to several types of traumatic events. First, prenatal drug exposure can be considered a form of trauma itself, with subtle but long-lasting sequelae at the neuro-behavioral level. Second, parents' addiction often entails a childrearing environment characterized by poor parenting skills, disadvantaged contexts and adverse childhood experiences (ACEs), leading to dysfunctional outcomes. Young adults born from/raised by parents with drug problems and diagnosed with a Substance Used Disorder (SUD) themselves might display a particularly severe condition in terms of cognitive deficits and impaired personality function. This preliminary study aims to investigate the role of early exposure to drugs as a traumatic event, capable of affecting the psychological status of young drug addicts. In particular, it intends to examine the neuropsychological functioning and personality profile of young adults with severe SUDs who were exposed to drugs early in their family context. The research involved three groups, each consisting of 15 young adults (aged 18–24): a group of inpatients diagnosed with SUDs and exposed to drugs early, a comparison group of non-exposed inpatients and a group of non-exposed youth without SUDs. A neuropsychological battery (Esame Neuropsicologico Breve-2), an assessment procedure for personality disorders (Shedler-Westen Assessment Procedure-200) and the Symptom CheckList-90-Revised were administered. According to present preliminary results, young drug addicts exposed to drugs during their developmental age were characterized by elevated rates of neuropsychological impairments, especially at the expense of attentive and executive functions (EF); personality disorders were also common but did not differentiate them from non-exposed youth with SUDs. Alternative multi-focused prevention and intervention programs are needed for children of drug-misusing parents, addressing EF and adopting a trauma-focused approach.

Contributions of a Child's Built, Natural, and Social Environments to Their General Cognitive Ability: A Systematic Scoping Review

The etiology of a child’s cognitive ability is complex, with research suggesting that it is not attributed to a single determinant or even a defined period of exposure. Rather, cognitive development is the product of cumulative interactions with the environment, both negative and positive, over the life course. The aim of this systematic scoping review was to collate evidence associated with children’s cognitive health, including inherent factors as well as chemical and non-chemical stressors from the built, natural, and social environments. Three databases were used to identify recent epidemiological studies (2003–2013) that examined exposure factors associated with general cognitive ability in children. Over 100 factors were evaluated from 258 eligible studies. We found that recent literature mainly assessed the hypothesized negative effects of either inherent factors or chemical exposures present in the physical environment. Prenatal growth, sleep health, lead and water pollutants showed consistent negative effects. Of the few studies that examined social stressors, results consistently showed cognitive development to be influenced by both positive and negative social interactions at home, in school or the community. Among behavioral factors related to diet and lifestyle choices of the mother, breastfeeding was the most studied, showing consistent positive associations with cognitive ability. There were mostly inconsistent results for both chemical and non-chemical stressors. The majority of studies utilized traditional exposure assessments, evaluating chemical and non-chemical stressors separately. Collective evidence from a limited number of studies revealed that cumulative exposure assessment that incorporates multiple chemical and non-chemical stressors over the life course may unravel the variability in effect on cognitive development and help explain the inconsistencies across studies. Future research examining the interactions of multiple stressors within a child’s total environment, depicting a more real-world exposure, will aid in understanding the cumulative effects associated with a child’s ability to learn.

Effects of prenatal cocaine exposure on adolescent development

The associations between prenatal cocaine exposure (PCE) and adolescent behavior, cognitive development, and physical growth were examined in 219 15-year-olds who have participated in a longitudinal study since their fourth gestational month. During the first trimester, 42% of the women used cocaine, with use declining across pregnancy. At the 15-year follow-up, the caregivers were, on average, 43 years old, had 13 years of education, and 50% were African American. First trimester PCE was not associated with global cognitive development or with measures of learning and memory. First trimester PCE was significantly related to adolescent-reported delinquent behavior, poorer problem solving and abstract reasoning, and reduced weight, height, and head circumference at 15 years. These results were significant after other factors that affect these domains were controlled in regression analyses. In addition, exposure to violence partially mediated the effect of PCE on delinquent behavior. These adolescent domains are important because they are predictors of poorer adult functioning.

Level of intrauterine cocaine exposure and neuropsychological test scores in preadolescence: subtle effects on auditory attention and narrative memory

Neuropsychological processes such as attention and memory contribute to children's higher-level cognitive and language functioning and predict academic achievement. The goal of this analysis was to evaluate whether level of intrauterine cocaine exposure (IUCE) alters multiple aspects of preadolescents' neuropsychological functioning assessed using a single age-referenced instrument, the NEPSY: A Developmental Neuropsychological Assessment (NEPSY) (Korkman et al., 1998), after controlling for relevant covariates. Participants included 137 term 9.5-year-old children from low-income urban backgrounds (51% male, 90% African American/Caribbean) from an ongoing prospective longitudinal study. Level of IUCE was assessed in the newborn period using infant meconium and maternal report. 52% of the children had IUCE (65% with lighter IUCE, and 35% with heavier IUCE), and 48% were unexposed. Infants with Fetal Alcohol Syndrome, HIV seropositivity, or intrauterine exposure to illicit substances other than cocaine and marijuana were excluded. At the 9.5-year follow-up visit, trained examiners masked to IUCE and background variables evaluated children's neuropsychological functioning using the NEPSY. The association between level of IUCE and NEPSY outcomes was evaluated in a series of linear regressions controlling for intrauterine exposure to other substances and relevant child, caregiver, and demographic variables. Results indicated that level of IUCE was associated with lower scores on the Auditory Attention and Narrative Memory tasks, both of which require auditory information processing and sustained attention for successful performance. However, results did not follow the expected ordinal, dose-dependent pattern. Children's neuropsychological test scores were also altered by a variety of other biological and psychosocial factors.

Prenatal substance abuse: short- and long-term effects on the exposed fetus

Prenatal substance abuse continues to be a significant problem in this country and poses important health risks for the developing fetus. The primary care pediatrician's role in addressing prenatal substance exposure includes prevention, identification of exposure, recognition of medical issues for the exposed newborn infant, protection of the infant, and follow-up of the exposed infant. This report will provide information for the most common drugs involved in prenatal exposure: nicotine, alcohol, marijuana, opiates, cocaine, and methamphetamine.

Developmental and behavioral consequences of prenatal cocaine exposure: a review

Substance use among pregnant women continues to be a major public health concern, posing potential risk to their drug-exposed children as well as burdens on society. This review is intended to discuss the most recent literature regarding the association between in utero cocaine exposure and developmental and behavioral outcomes from birth through adolescence across various domains of functioning (growth, neurobiology, intelligence, academic achievement, language, executive functioning, behavioral regulation and psychopathology). In addition, methodological limitations, associated biological, sociodemographic and environmental risk factors and future directions in this area of research are discussed. Given the large number of exposed children in the child welfare system and the increased need for medical, mental health and special education services within this population, more definitively documenting associations between prenatal cocaine exposure and later child outcomes is essential in order to be able to prospectively address the many significant public health, economic and public policy implications.

Prenatal IV Cocaine: Alterations in Auditory Information Processing

One clue regarding the basis of cocaine-induced deficits in attentional processing is provided by the clinical findings of changes in the infants' startle response; observations buttressed by neurophysiological evidence of alterations in brainstem transmission time. Using the IV route of administration and doses that mimic the peak arterial levels of cocaine use in humans, the present study examined the effects of prenatal cocaine on auditory information processing via tests of the auditory startle response (ASR), habituation, and prepulse inhibition (PPI) in the offspring. Nulliparous Long-Evans female rats, implanted with an IV access port prior to breeding, were administered saline, 0.5, 1.0, or 3.0 mg/kg/injection of cocaine HCL (COC) from gestation day (GD) 8-20 (1×/day-GD8-14, 2×/day-GD15-20). COC had no significant effects on maternal/litter parameters or growth of the offspring. At 18-20 days of age, one male and one female, randomly selected from each litter displayed an increased ASR (>30% for males at 1.0 mg/kg and >30% for females at 3.0 mg/kg). When reassessed in adulthood (D90-100), a linear dose-response increase was noted on response amplitude. At both test ages, within-session habituation was retarded by prenatal cocaine treatment. Testing the females in diestrus vs. estrus did not alter the results. Prenatal cocaine altered the PPI response function across interstimulus interval and induced significant sex-dependent changes in response latency. Idazoxan, an α(2)-adrenergic receptor antagonist, significantly enhanced the ASR, but less enhancement was noted with increasing doses of prenatal cocaine. Thus, in utero exposure to cocaine, when delivered via a protocol designed to capture prominent features of recreational usage, causes persistent, if not permanent, alterations in auditory information processing, and suggests dysfunction of the central noradrenergic circuitry modulating, if not mediating, these responses.

Are there effects of intrauterine cocaine exposure on delinquency during early adolescence? A preliminary report

OBJECTIVE

To ascertain whether level of intrauterine cocaine exposure (IUCE) is associated with early adolescent delinquent behavior, after accounting for prenatal exposures to other psychoactive substances and relevant psychosocial factors.

METHODS

Ninety-three early adolescents (12.5-14.5 years old) participating since birth in a longitudinal study of IUCE reported delinquent acts via an audio computer-assisted self-interview. Level of IUCE and exposure to cigarettes, alcohol, and marijuana were determined by maternal report, maternal and infant urine assays, and infant meconium assays at birth. Participants reported their exposure to violence on the Violence Exposure Scale for Children-Revised at ages 8.5, 9.5, and 11 years and during early adolescence, and the strictness of supervision by their caregivers during early adolescence.

RESULTS

Of the 93 participants, 24 (26%) reported ≥ 3 delinquent behaviors during early adolescence. In the final multivariate model (including level of IUCE and cigarette exposure, childhood exposure to violence, and caregiver strictness/supervision) ≥ 3 delinquent behaviors were not significantly associated with level of IUCE but were significantly associated with intrauterine exposure to half a pack or more of cigarettes per day and higher levels of childhood exposure to violence, effects substantially unchanged after control for early adolescent violence exposure.

CONCLUSIONS

In this cohort, prospectively ascertained prenatal exposure to cigarettes and childhood exposure to violence are associated with self-reported delinquent behaviors during early adolescence. Contrary to initial popular predictions, intrauterine cocaine is not a strong predictor of adolescent delinquent behaviors in this cohort.

Early adolescent executive functioning, intrauterine exposures and own drug use

Individual differences in adolescents' executive functioning are often attributed either to intrauterine substance exposure or to adolescents' own substance use, but both predictors typically have not been evaluated simultaneously in the same study. This prospective study evaluated whether intrauterine drug exposures, the adolescents' own substance use, and/or their potential interactions are related to poorer executive functioning after controlling for important contextual variables. Analyses were based on data collected on a sample of 137 predominantly African-American/African Caribbean adolescents from low-income urban backgrounds who were followed since their term birth. Intrauterine substance exposures (cocaine, marijuana, alcohol, and cigarettes) and adolescents' substance use were documented using a combination of biological assays and maternal and adolescent self-report. At 12-14 years of age, examiners masked to intrauterine exposures and current substance use assessed the adolescents using the Delis-Kaplan Executive Function System (D-KEFS), an age-referenced instrument evaluating multiple dimensions of executive functioning (EF). Results of covariate-controlled analyses in this study suggest that when intrauterine substance exposures and young adolescents' substance use variables were in the same analysis models, subtle differences in specific EF outcomes were identifiable in this non-referred sample. While further study with larger samples is indicated, these findings suggest that 1) research on adolescent substance use and intrauterine exposure research should evaluate both predictors simultaneously, 2) subtle neurocognitive effects associated with specific intrauterine drug exposures can be identified during early adolescence, and 3) intrauterine substance exposure effects may differ from those associated with adolescents' own drug use.

Adolescent initiation of licit and illicit substance use: Impact of intrauterine exposures and post-natal exposure to violence

Whether intrauterine exposures to alcohol, tobacco, marijuana, or cocaine predispose offspring to substance use in adolescence has not been established. We followed a sample of 149 primarily African American/African Caribbean, urban adolescents, recruited at term birth, until age 16 to investigate intrauterine cocaine exposure (IUCE). We found that in Kaplan-Meier analyses higher levels of IUCE were associated with a greater likelihood of initiation of any substance (licit or illicit), as well as marijuana and alcohol specifically. Adolescent initiation of other illicit drugs and cigarettes were analyzed only in the "any" summary variable since they were used too infrequently to analyze as individual outcomes. In Cox proportional hazard models controlling for intrauterine exposure to alcohol, tobacco, and marijuana and demographic and post-natal covariates, those who experienced heavier IUCE had a greater likelihood of initiation of any substance, and those with lighter intrauterine marijuana exposure had a greater likelihood of initiation of any substance as well as of marijuana specifically. Time-dependent higher levels of exposure to violence between ages of 8 and 16 were also robustly associated with initiation of any licit or illicit substance, and of marijuana, and alcohol particularly.

The effects of prenatal cocaine on language development at 10 years of age

OBJECTIVE

To examine the long term effects of prenatal cocaine exposure (PCE) on the language development of 10-year-old children utilizing a prospective design, controlling for confounding drug and environmental factors.

PARTICIPANTS

Children exposed to cocaine in utero (PCE; n=175) and non-exposed children (NCE; n=175) were followed prospectively to 10years of age and were compared on language subscales of the Test of Language Development-Intermediate 3rd Edition (TOLD-I:3) and phonological processing as measured by the Comprehensive Test of Phonological Processing (CTOPP).

METHODS

Multivariate analysis of covariance (MANCOVA), linear regression, and logistic regressions were used to evaluate the relationship of prenatal cocaine exposure to language development, while controlling for confounders.

RESULTS

After controlling for confounding variables, prenatal cocaine effects were observed for specific aspects of language including syntax (Sentence Combining subtest of the TOLD-I:3, p=0.001), semantics (Malopropism subtest of the TOLD-I:3, p=0.05) and phonological processing (Phonological Awareness subscale, p=0.01). The caregiver factors of vocabulary, HOME, and psychological symptoms also had consistent effects on language subtests and phonological processing scores. Children with PCE who experienced foster or adoptive care had enhanced language development compared to those living with birth mothers or in relative care. Cocaine exposed girls had lower scores on the phonological awareness subscale of the CTOPP than non-exposed girls.

CONCLUSIONS

PCE has subtle effects on specific aspects of language development and phonological processing at age 10, even after controlling for confounding variables. Environmental factors (i.e., postnatal lead exposure, home environment, and caregiver vocabulary and psychological symptoms) also impact language skills at 10years. Adoptive or foster care appears to enrich PCE children's linguistic environment and protects children against language delay in the PCE sample.

Children of addicted women

The purpose of this article was to review follow up studies of children with prenatal drug exposure from preschool through adolescence. Specifically, the authors focus on the effects of prenatal exposure to cocaine, methamphetamine, and opiates on behavior and development. The largest number of studies have examined cocaine-exposed children. The authors identified 42 studies that suggest that there are unique effects of prenatal cocaine exposure on 4- to 13-year-old children, particularly in the areas of behavior problems, attention, language, and cognition. In addition, studies make reasonable attempts to control for possible confounding factors. Systematic research on the long-term effects of prenatal methamphetamine exposure is just beginning but seems to be showing similar effects to that of cocaine. The literature on the on the long-term effects of children with prenatal opiate exposure is more substantial than the methamphetamine literature but it is still relatively sparse and surprising in that there is little recent work. Thus, there are no studies on the current concerns with opiates used for prescription mediation. There is a growing literature using neuroimaging techniques to study the effects of prenatal drug exposure that holds promise for understanding brain/behavior relationships. In addition to pharmacological and teratogenic effects, drugs can also be viewed from a prenatal stressor model. The author discuss this "fetal origins" approach that involves fetal programming and the neuroendocrine system and the potential implications for adolescent brain and behavioral development.

Continued effects of prenatal cocaine use: preschool development

The relationship between prenatal cocaine use and preschooler's physical and cognitive development and behavioral characteristics was examined, controlling for other influences on child development. On average, children were 38.5 months old, women were 29.4 years old, had 12.3 years of education, and 47% were African American. During the first trimester, 18% of the women were frequent cocaine users (> or = 1 line/day). First trimester cocaine exposure predicted decreased head circumference at 3 years and lower scores on the short-term memory subscale of the Stanford-Binet Intelligence Scale (SBIS) [74]. There was no significant relationship between prenatal cocaine use and the other SBIS scales. First trimester cocaine use also predicted more total, internalizing, and externalizing behavior problems on the Child Behavior Checklist [3] and higher scores on the fussy/difficult scale of the Infant Characteristics Questionnaire [6]. Children who were exposed to cocaine throughout pregnancy had more behavior problems and were more fussy compared to children of women who never used cocaine prenatally. A repeated measures analysis showed that children of first trimester cocaine users became more fussy over time. These detrimental effects on growth and behavior are consistent with other reports in the literature and with the hypothesis that prenatal cocaine exposure affects development through changes in neurotransmitter systems.

Prenatal cocaine exposure alters emotional arousal regulation and its effects on working memory

While prenatal cocaine exposure (PCE) has been associated with arousal dysregulation and attentional impairments in both human and animal studies, the neurobiological bases of these teratogenic effects have not been well characterized. In the current study, we report functional neuroimaging observations of these effects in exposed youth. Using functional magnetic resonance imaging (fMRI), we embedded task-irrelevant emotional distracters in a working memory task to examine the interaction of emotional arousal and memory in 33 PCE and 23 non-exposed adolescents. Though with similar behavioral performance, the two groups exhibited different activation patterns associated with emotion-memory interactions. On the one hand, higher memory load attenuated emotion-related amygdala activation in controls but not in the exposed adolescents; on the other hand, prefrontal activation associated with memory load decreased in the presence of emotional distraction in the controls but increased in the exposed group. These group interaction differences suggest neurobiological substrates for arousal-associated neuronal alterations related to prenatal cocaine exposure. Consistent with previous findings in behavioral and physiological studies, the present neuroimaging data provided more in-depth evidence supporting the view that PCE has significant long-term teratogenic effect on arousal regulation system.

Children with and without gestational cocaine exposure: a neurocognitive systems analysis

BACKGROUND

Concern for effects of gestational cocaine exposure (GCE) on human neurocognitive (NC) development is based on effects of cocaine on blood flow to the fetus and impact of cocaine on developing monoaminergic systems. GCE has been shown to affect language, attention and perceptual reasoning skills.

OBJECTIVE

Our objective was to investigate effects of GCE on 7 NC systems, assessed behaviorally in middle school-aged, low socioeconomic status subjects followed prospectively since birth.

METHODS

55 GCE and 65 non-exposed Control subjects were tested with a battery of 14 tasks adapted from neuroimaging and lesion literature designed to tap 3 frontal systems (Cognitive Control, Working Memory, and Reward Processing) and 4 non-frontal systems (Language, Memory, Spatial Cognition, and Visual Cognition). Using multivariate analysis of covariance, we assessed the relation between NC functioning and GCE status with the following covariates: age at testing; gender; gestational exposure to cigarettes, alcohol and marijuana; foster care placement; caregiver current cocaine use; and two indices of childhood environment.

RESULTS

None of the analyses showed an effect of GCE on NC function. In contrast, child characteristics, including age at testing and childhood environment, were associated with NC function.

CONCLUSIONS

In this cohort there is either no effect of GCE on NC function at middle school age, or that effect is less pronounced than the effect of age or childhood environment.

Intrauterine cocaine exposure and executive functioning in middle childhood

This longitudinal study evaluated whether the level of intrauterine cocaine exposure (IUCE) or the interaction between IUCE and contextual variables was related during middle childhood to executive functioning, as assessed with the Stroop Color-Word and Rey Osterrieth Complex Figure tests. The Stroop Interference score measures verbal inhibitory control while the Rey Osterrieth Organizational score evaluates skills such as planning, organization and perception. Masked examiners assessed 143 children at 9.5 and 11 years of age (74 with IUCE and 69 demographically similar children without IUCE). Level of IUCE (Unexposed; Lighter, and Heavier) was documented by positive postpartum maternal reports and infant meconium assays. In covariate-controlled regressions, level of IUCE was not significantly associated with Stroop Interference or Rey Osterrieth Organization scores. However, in covariate controlled post-hoc tests comparing the Heavier exposed group to the combined Lighter/Unexposed group, children in the Heavier group had significantly poorer Stroop Interference scores, but there was no significant group difference for Rey Osterrieth Organizational scores. Children's average Organization scores in Unexposed, Lighter, and Heavier exposed groups were well below the test norm means. Results of this study indicate that heavier IUCE may be associated with mild compromise on school-aged children's ability to inhibit prepotent verbal responses.

Executive functioning at ages 5 and 7 years in children with prenatal cocaine exposure

This prospective longitudinal study evaluated the effect of prenatal cocaine exposure (PCE) on executive functioning in 5- and 7-year-old children. In total, 154 pregnant cocaine users, identified by urine toxicology and structured interviews, were matched to 154 nonusers. Children were assessed by certified masked evaluators, and caregivers were interviewed by experienced staff during home visits. In approximately 90% of the surviving sample tested at ages 5 and 7 years, structural equation modeling demonstrated that an increased head circumference at birth (adjusted for gestation) significantly predicted better performance on executive functioning, and that PCE was indirectly related to executive functioning through its significant negative effect on head circumference at birth. At age 5 years, quality of environment also predicted executive functioning, and the R(2) for the total model was 0.24. At 7 years, caregiver functioning predicted quality of environment, which in turn was positively related to executive functioning, and girls had better executive functioning. The total model at age 7 years accounted for 30% of the variance in executive functioning.

Children's cognitive ability from 4 to 9 years old as a function of prenatal cocaine exposure, environmental risk, and maternal verbal intelligence

This study examined the effects of prenatal cocaine exposure, environmental risk, and maternal verbal intelligence on children's cognitive ability. Gender and age were examined as moderators of potential cocaine exposure effects. The Stanford-Binet IV intelligence test was administered to 231 children (91 cocaine exposed, 140 unexposed) at ages 4, 6, and 9 years. Neonatal medical risk and other prenatal exposures (alcohol, cigarettes, and marijuana) were also examined for their unique effects on child IQ. Mixed models analysis indicated that prenatal cocaine exposure interacted with gender, as cocaine-exposed boys had lower composite IQ scores. Age at assessment did not moderate this relation, indicating that cocaine-exposed boys had lower IQs across this age period. A stimulating home environment and high maternal verbal IQ also predicted higher composite IQ scores. Cocaine-exposed boys had lower scores on the Abstract/Visual Reasoning subscale, with trends for lower scores on the Short-Term Memory and Verbal Reasoning subscales, as exposure effects were observed across domains. The findings indicate that cocaine exposure continues to place children at risk for mild cognitive deficits into preadolescence. Possible mechanisms for the Exposure x Gender interaction are discussed.

A systematic review of challenging behaviors in children exposed prenatally to substances of abuse

A review of the existing literature on the occurrence of challenging behavior among children with prenatal drug exposure was conducted. While a large number of studies were identified that evaluated various outcomes of prenatal drug exposure, only 37 were found that directly evaluated challenging behaviors. Of the 37 studies, 23 focused on prenatal cocaine exposure, and 14 focused on prenatal alcohol exposure; most studies relied on broadband measures such as the CBCL for the assessment of challenging behavior. Among the 37 studies, a clear role for the postnatal environment on developing challenging behaviors was evident; however, prenatal alcohol exposure showed a much clearer independent effect upon challenging behaviors than was noted in the prenatal cocaine studies. Additionally, only 3 of the 37 studies addressed interventions for challenging behaviors, each of which showed an improvement in child behavior or parent-child interactions. As researchers have continued to show the importance of the postnatal environment, it is likely that interventions addressing specific environmental risk factors will be helpful to reduce or prevent challenging behaviors among this population.

Effects of prenatal cocaine exposure on special education in school-aged children

OBJECTIVE

The objective of this study was to evaluate the effects of prenatal cocaine exposure on special education at age 7 with adjustment for covariates.

METHODS

As part of the prospective, longitudinal, multisite study of children with prenatal cocaine exposure (Maternal Lifestyle Study), school records were reviewed for 943 children at 7 years to determine involvement in special education outcomes: (1) individualized education plan; (2) special education conditions; (3) support services; (4) special education classes; and (5) speech and language services. Logistic regression was used to examine the effect of prenatal cocaine exposure on these outcomes with environmental, maternal, and infant medical variables as covariates, as well as with and without low child IQ.

RESULTS

Complete data for each analysis model were available for 737 to 916 children. When controlling for covariates including low child IQ, prenatal cocaine exposure had a significant effect on individualized education plan. When low child IQ was not included in the model, prenatal cocaine exposure had a significant effect on support services. Male gender, low birth weight, white race, and low child IQ also predicted individualized education plan. Low birth weight and low child IQ were significant in all models. White race was also significant in speech and language services. Other covariate effects were model specific. When included in the models, low child IQ accounted for more of the variance and changed the significance of other covariates.

CONCLUSIONS

Prenatal cocaine exposure increased the likelihood of receiving an individualized education plan and support services, with adjustment for covariates. Low birth weight and low child IQ increased the likelihood of all outcomes. The finding that white children were more likely to get an individualized education plan and speech and language services could indicate a greater advantage in getting educational resources for this population.

Late neurodevelopmental effects of early exposures to chemical contaminants: reducing uncertainty in epidemiological studies

Early exposures to environmental chemicals are reliably associated with late neurotoxicities in children. However, substantial scatter of observations exists around the estimated dose-effect relationships. This variability has many potential sources, one of which is interindividual differences in susceptibility. Such differences imply that the long-term impacts of exposure will not the same for all individuals, but will vary depending on a variety of factors that might either aggravate or mitigate contaminant effects. These include co-exposures, genetic polymorphisms and characteristics of the social environment. The context dependence of contaminant effects has implications both for study designs and analytical approaches. In addition, a systems approach to understanding the associations among contaminant exposures, covariates and health outcomes is necessary.

Lead neurotoxicity in children: decomposing the variability in dose-effect relationships

BACKGROUND

Enormous progress has been made in recent decades in our understanding of lead neurotoxicology in children, but an important obstacle to additional progress is the striking variability that is evident in any plot of a lead biomarker versus a health endpoint.

METHODS

In this article, three potential sources of variability are identified: (1) errors or imprecision in characterizing dose (and/or outcome); (2) incomplete characterization of endpoint variance attributable to factors other than lead; and (3) inter-individual differences in susceptibility to lead neurotoxicity.

RESULTS

Strategies are suggested for reducing the variability contributed by these sources, including the development of validated PBPK models and biomarkers of early biological effects; the development of more comprehensive models of outcome variance and, specifically, the application of multi-level models that incorporate supra-individual and supra-family risk factors; and the use of study designs that permit assessments of the effect modifying influence of contextual factors on the form and severity of neurotoxicity.

CONCLUSION

Decomposing the variability in the distribution of observed scores around the best-fit lines that describe the dose-effect relationships for lead neurotoxicity in children is a major research need.

Maternal depression and cognitive features of 9-year-old children prenatally-exposed to cocaine

This study evaluated cocaine exposure and maternal characteristics as competing predictors of school-age cognitive, achievement, and language performance. One group of 47 exposed 9-year-old children were first studied in an earlier prenatal study. A non-exposed contrast group (n = 46) served as a reference. Maternal measures included: IQ, psychopathology, drugs, demographics, and environment. Child intelligence, language, and achievement scores were inversely related to maternal IQ and depression scores, with cocaine exposure significant secondary or tertiary predictors for many children. Verbal IQ scores of exposed children strongly reflected maternal depression (r = .54) but no such relationship was found among the non-exposed cohort (r = .00).

Learning disabilities and intellectual functioning in school-aged children with prenatal cocaine exposure

Risk for developing a learning disability (LD) or impaired intellectual functioning by age 7 was assessed in full-term children with prenatal cocaine exposure drawn from a cohort of 476 children born full term and enrolled prospectively at birth. Intellectual functioning was assessed using the Wechsler Intelligence Scale for Children-Third Edition (Wechsler, 1991) short form, and academic functioning was assessed using the Wechsler Individual Achievement Test (WIAT; Wechsler, 1993) Screener by examiners blind to exposure status. LDs were categorized based on ability-achievement discrepancy scores, using the regression-based predicted achievement method described in the WIAT manual. The sample in this report included 409 children (212 cocaine-exposed, 197 non-cocaine-exposed) from the birth cohort with available data. Cumulative incidence proportions and relative risk values were estimated using STATA software (Statacorp, 2003). No differences were found in the estimate of relative risk for impaired intellectual functioning (IQ below 70) between children with and without prenatal cocaine exposure (estimated relative risk = .95; 95% confidence interval [CI] = 0.65, 1.39; p = .79). The cocaine-exposed children had 2.8 times greater risk of developing a LD by age 7 than non-cocaine-exposed children (95% CI = 1.05, 7.67; p = .038; IQ >/= 70 cutoff). Results remained stable with adjustment for multiple child and caregiver covariates, suggesting that children with prenatal cocaine exposure are at increased risk for developing a learning disability by age 7 when compared to their non-cocaine-exposed peers.

Prenatal drug exposure effects on subsequent vulnerability to drug abuse

Research has shown that both prenatal alcohol and tobacco exposure are associated with increased risk of significant adverse medical, developmental, and behavioral outcomes including substance abuse. Research on the outcomes of prenatal exposure to illicit drugs (PNDE) has also found increased physical and behavioral problems for gestationally drug-exposed children. However, a clear picture has not emerged on whether the consequences of PNDE are independent from those associated with having a substance abusing parent and whether PNDE increases vulnerability to drug abuse. Because of its typical co-occurrence with factors inherent in having a drug-abusing parent, PNDE is at least a marker of significant increased risk for a range of negative outcomes including greater vulnerability to substance abuse. Although a review of the relevant research literatures indicates that the direct consequences of PNDE appear to be generally both subtle and nonglobal, PNDE does appear to have negative developmental and behavioral outcomes, and there is evidence that it is a modest direct contributor to increased substance abuse vulnerability.

Prenatal cocaine exposures and dose-related cocaine effects on infant tone and behavior

BACKGROUND

In experimental models, prenatal cocaine exposure has been found to perturb monoaminergic development. In humans, numerous studies have sought clinical correlates, but few have focused on dose-related effects, especially as regards neurologic function beyond the neonatal period.

OBJECTIVE

To assess whether prenatal cocaine exposure has adverse effects on infant neurologic, developmental and behavioral outcomes and whether any effects are dose-dependent.

DESIGN/METHODS

Infants (398) were enrolled at birth from an urban hospital. Drug exposure was ascertained with biomarkers in hair (n=395), urine (n=170) and meconium (n=109). Children were followed prospectively and 286 (72%) were evaluated blind to drug exposure at 6 months of age with the Bayley scales, Fagan Scale of Infant Intelligence and a standardized neurological examination.

RESULTS

Certain neurological findings increased significantly by the amount of cocaine detected in maternal hair, e.g. abnormality of tone, as indicated by extensor posture was detected among 28% of cocaine-unexposed infants, 43% of infants exposed to lower and 48% exposed to higher cocaine levels in maternal hair (p<0.009). Persistent fisting increased in a similar dose-dependent manner. These associations persisted in adjusted analyses. Prenatal cocaine exposure was not associated with developmental scores (mental, motor or novelty preference) but was associated with lower orientation scores in adjusted analyses.

CONCLUSIONS

At 6 months of age, prenatal cocaine exposure was associated with abnormalities of tone and posture and with lower orientation scores. Perturbations in monoaminergic systems by cocaine exposure during fetal development may explain the observed neurological and behavioral symptoms. Whether such findings in infancy increase the risk of later neurobehavioral problems requires further study.

Diffusion tensor imaging of frontal white matter and executive functioning in cocaine-exposed children

BACKGROUND

Although animal studies have demonstrated frontal white matter and behavioral changes resulting from prenatal cocaine exposure, no human studies have associated neuropsychological deficits in attention and inhibition with brain structure. We used diffusion tensor imaging to investigate frontal white matter integrity and executive functioning in cocaine-exposed children.

METHODS

Six direction diffusion tensor images were acquired using a Siemens 3T scanner with a spin-echo echo-planar imaging pulse sequence on right-handed cocaine-exposed (n = 28) and sociodemographically similar non-exposed children (n = 25; mean age: 10.6 years) drawn from a prospective, longitudinal study. Average diffusion and fractional anisotropy were measured in the left and right frontal callosal and frontal projection fibers. Executive functioning was assessed using two well-validated neuropsychological tests (Stroop color-word test and Trail Making Test).

RESULTS

Cocaine-exposed children showed significantly higher average diffusion in the left frontal callosal and right frontal projection fibers. Cocaine-exposed children were also significantly slower on a visual-motor set-shifting task with a trend toward lower scores on a verbal inhibition task. Controlling for gender and intelligence, average diffusion in the left frontal callosal fibers was related to prenatal exposure to alcohol and marijuana and an interaction between cocaine and marijuana exposure. Performance on the visual-motor set-shifting task was related to prenatal cocaine exposure and an interaction between cocaine and tobacco exposure. Significant correlations were found between test performance and fractional anisotropy in areas of the frontal white matter.

CONCLUSIONS

Prenatal cocaine exposure, alone and in combination with exposure to other drugs, is associated with slightly poorer executive functioning and subtle microstructural changes suggesting less mature development of frontal white matter pathways. The relative contribution of postnatal environmental factors, including characteristics of the caregiving environment and stressors associated with poverty and out-of-home placement, on brain development and behavioral functioning in polydrug-exposed children awaits further research.

Prenatal cocaine exposure and children's language functioning at 6 and 9.5 years: moderating effects of child age, birthweight, and gender

OBJECTIVE

To evaluate whether prenatal cocaine exposure (PCE), or the interaction between PCE and contextual variables, is associated with children's language at age 6 and 9.5 years, adjusting for relevant covariates.

METHODS

Analyses were based on 160 low-income, urban children from a prospective study who completed a standardized language assessment at 6 and 9.5 years. PCE was determined using neonatal meconium assays and maternal self-report.

RESULTS

Significant interaction effects of PCE on language outcomes were found in multivariate longitudinal analyses using generalized estimating equations (GEE). Children with PCE had lower receptive language than unexposed children at 6 but not at 9.5 years, lower expressive language if they had lower birthweight, and lower expressive and total language if they were female. Other risk (e.g., violence exposure) and protective factors (e.g., preschool experience) were related to language outcomes regardless of PCE status.

CONCLUSIONS

Age, birthweight, and gender moderated the relation between PCE and school-aged children's language.