R. Colin Carter

Domain-specific effects of prenatal exposure to PCBs, mercury, and lead on infant cognition: Results from the environmental contaminants and child development study in nunavik

Background: Polychlorinated biphenyls (PCBs), methylmercury (MeHg), and lead (Pb) are environmental contaminants known for their adverse effects on cognitive development. Objectives: In this study we examined the effects of prenatal exposure to PCBs, MeHg, and Pb on cognitive development in a sample of Inuit infants from Arctic Québec. Methods: Mothers were recruited at local prenatal clinics. PCBs, mercury (Hg), Pb, and two seafood nutrients—docosahexaenoic acid (DHA) and selenium (Se)—were measured in umbilical cord blood. Infants (n = 94) were assessed at 6.5 and 11 months of age on the Fagan Test of Infant Intelligence (FTII), A-not-B test, and Bayley Scales of Infant Development–2nd Edition (BSID-II). Results: Multiple regression analyses revealed that higher prenatal PCB exposure was associated with decreased FTII novelty preference, indicating impaired visual recognition memory. Prenatal Hg was associated with poorer performance on A-not-B, which depends on working memory and is believed to be a precursor of executive function. Prenatal Pb was related to longer FTII fixation durations, indicating slower speed of information processing. Conclusions: PCBs, MeHg, and Pb each showed specific and distinct patterns of adverse associations with the outcomes measured during infancy. By contrast, none of these exposures was associated with performance on the BSID-II, a global developmental measure. The more focused, narrow band measures of cognitive function that appeared to be sensitive to these exposures also provide early indications of long-term impairment in specific domains that would otherwise not likely be evident until school age. Citation: Boucher O, Muckle G, Jacobson JL, Carter RC, Kaplan-Estrin M, Ayotte P, Dewailly É, Jacobson SW. 2014. Domain-specific effects of prenatal exposure to PCBs, mercury, and lead on infant cognition: results from the Environmental Contaminants and Child Development Study in Nunavik. Environ Health Perspect 122:310–316;u2002http://dx.doi.org/10.1289/ehp.1206323

Infant emotional withdrawal: a precursor of affective and cognitive disturbance in fetal alcohol spectrum disorders.

BACKGROUNDnOur aim was to test the hypothesis that emotional withdrawal is an early indicator of affective disorder in infants heavily exposed prenatally to alcohol, which is independent of alcohol-related effects on mother-infant interaction and temperament and discriminated between children later diagnosed with fetal alcohol syndrome (FAS) and partial FAS (PFAS) and predicted cognitive and affective outcomes at 5 and 9xa0years.nnnMETHODSnThe sample consisted of Cape Coloured (mixed ancestry) infants, whose mothers were interviewed during pregnancy regarding their alcohol consumption using a timeline follow-back approach. Infant emotional withdrawal (nxa0=xa085) was assessed on the Alarm Distress Baby Scale at 6.5xa0months. Mother-infant interaction was evaluated from video recordings during free play and infant feeding at 6.5xa0months (nxa0=xa0127). Infant temperament was assessed by maternal report on the EAS Temperament Survey at 13xa0months (nxa0=xa0119). Sociodemographic and psychological correlates of maternal alcohol use and infant iron deficiency were examined as potential confounders. The children were diagnosed for FAS/PFAS by expert dysmorphologists at 5xa0years, cognitive and affective function at 5 and 9xa0years.nnnRESULTSnPrenatal alcohol exposure was associated with increased infant emotional withdrawal and decreased activity, but unrelated to mother-infant interaction or any other temperament measures. Children later diagnosed with FAS and PFAS at 5xa0years exhibited more emotional withdrawal and less responsivity and activity as infants. Infant withdrawal, responsivity, quality of interaction, and maternal sensitivity also predicted poorer IQ and affective response at 5 and 9xa0years. When all 4 infant affective measures were examined simultaneously in a regression analysis, only infant emotional withdrawal persisted as a significant predictor of 9-year IQ.nnnCONCLUSIONSnThis study is the first to document a direct effect of fetal alcohol exposure on emotional withdrawal in infancy. These data link prenatal alcohol to a specific aspect of infant affective function not attributable to mother-infant interaction, infant temperament, or other socioemotional aspects of the infants environment and identify infant emotional withdrawal as an early indicator of affective disturbance, particularly in children later diagnosed with FAS and PFAS.

Effects of heavy prenatal alcohol exposure and iron deficiency anemia on child growth and body composition through age 9 years

BACKGROUNDnPrenatal alcohol exposure has been associated with pre- and postnatal growth restriction, but little is known about the natural history of this restriction throughout childhood or the effects of prenatal alcohol on body composition. The objective of this study was to examine the effects of heavy prenatal alcohol exposure on longitudinal growth and body composition.nnnMETHODSnEighty-five heavy drinking pregnant women (≥2xa0drinks/d or ≥4xa0drinks/occasion) and 63 abstaining and light-drinking controls (<1xa0drink/d, no binging) were recruited at initiation of prenatal care in an urban obstetrical clinic in Cape Town, South Africa and prospectively interviewed during pregnancy about alcohol, smoking, drug use, and demographics. Among their children, length/height, weight, and head circumference were measured at 6.5 and 12xa0months and at 5 and 9xa0years. Percent body fat (BF) was estimated at age 9xa0years using bioelectric impedance analysis.nnnRESULTSnIn multiple regression models with repeated measures (adjusted for confounders), heavy alcohol exposure was associated with reductions in weight (0.6xa0SD), length/height (0.5xa0SD), and head circumference (0.9xa0cm) from 6.5xa0months to 9xa0years that were largely determined at birth. These effects were exacerbated by iron deficiency in infancy but were not modified by iron deficiency or measures of food security at 5xa0years. An alcohol-related postnatal delay in weight gain was seen at 12xa0months. Effects on head circumference were greater at age 9 than at other age points. Although heavy alcohol exposure was not associated with changes in body composition, children with fetal alcohol syndrome (FAS) and partial fetal alcohol syndrome (PFAS) had lower percent BF than heavy exposed nonsyndromal and control children.nnnCONCLUSIONSnHeavy prenatal alcohol exposure is related to prenatal growth restriction that persists through age 9xa0years and an additional delay in weight gain during infancy. FAS and PFAS diagnoses are associated with leaner body composition in later childhood.

Fetal Alcohol-Related Growth Restriction from Birth through Young Adulthood and Moderating Effects of Maternal Prepregnancy Weight

BACKGROUNDnFetal alcohol-related growth restriction persists through infancy, but its impact later in life is less clear. Animal studies have demonstrated important roles for maternal nutrition in fetal alcohol spectrum disorders, but the impact of prenatal maternal body composition has not been studied in humans. This study examined the effects of prenatal alcohol exposure on longitudinal growth from birth through young adulthood and the degree to which maternal weight and body mass index (BMI) moderate these effects.nnnMETHODSnNearly 480 mothers were recruited at their first prenatal clinic visit to overrepresent moderate-to-heavy use of alcohol during pregnancy, including a 5% random sample of low-level drinkers and abstainers. They were interviewed at every prenatal visit about their alcohol consumption using a timeline follow-back approach. Their children were examined for weight, length/height, and head circumference at birth, 6.5 and 13 months, and 7.5, 14, and 19 years.nnnRESULTSnIn multiple regression models with repeated measures (adjusted for confounders), prenatal alcohol exposure was associated with longitudinal reductions in weight, height, and weight-for-length/BMI that were largely determined at birth. At low-to-moderate levels of exposure, these effects were more severe in infancy than in later childhood. By contrast, effects persisted among children whose mothers drank at least monthly and among those born to women with alcohol abuse and/or dependence who had consumed ≥ 4 drinks/occasion. In addition, effects on weight, height, and head circumference were markedly stronger among children born to mothers with lower prepregnancy weight.nnnCONCLUSIONSnThese findings confirm prior studies demonstrating alcohol-related reductions in weight, height, weight-for-height/BMI, and head circumference that persist through young adulthood. Stronger effects were seen among children born to mothers with smaller prepregnancy weight, which may have been because of attainment of higher blood alcohol concentrations in smaller mothers for a given amount of alcohol intake or to increased vulnerability in infants born to women with poorer nutrition.

Fetal alcohol growth restriction and cognitive impairment

BACKGROUND: Although both fetal and long-term growth restriction are well documented in fetal alcohol spectrum disorders, effects on pattern of growth trajectory have not been characterized. Furthermore, the degree to which growth trajectories are related to fetal alcohol-related neurocognitive deficits is unknown. METHODS: Ninety-three heavy drinking pregnant women and 64 controls were recruited at initiation of prenatal care in Cape Town, South Africa. Small for gestational age (SGA) was defined as birth weight <10th percentile. Length/height, weight, and head circumference were measured at 6.5 and 12 months and 5, 9, and 13 years. Four growth trajectories were identified: SGA with long-term postnatal growth restriction (length/height-for-age <10th percentile through 13 years); SGA with catch-up growth; no SGA or postnatal growth restriction; and late-onset postnatal stunting. IQ was assessed at 5 and 10 years, and learning, memory, and executive function at 10 years. RESULTS: Children born SGA with postnatal growth restriction were most heavily exposed. Exposure was intermediate for those born SGA with catch-up growth and lowest for those without prenatal or postnatal growth restriction. Effects on neurocognition were strongest in children with both prenatal and long-term growth restriction, more moderate in those with fetal growth restriction and postnatal catch-up, and weakest in those without growth restriction. CONCLUSIONS: These findings validate the use of growth restriction in the diagnosis of fetal alcohol spectrum disorders and identify growth trajectory as a biomarker of which heavily exposed children are at greatest risk for cognitive developmental deficits.

Alcohol, Methamphetamine, and Marijuana Exposure Have Distinct Effects on the Human Placenta.

BACKGROUNDnAnimal studies have demonstrated adverse effects of prenatal alcohol exposure on placental development, but few studies have examined these effects in humans. Little is known about effects of prenatal exposure to methamphetamine, marijuana, and cigarette smoking on placental development.nnnMETHODSnPlacentas were collected from 103 Cape Coloured (mixed ancestry) pregnant women recruited at their first antenatal clinic visit in Cape Town, South Africa. Sixty-six heavy drinkers and 37 nondrinkers were interviewed about their alcohol, cigarette smoking, and drug use at 3 antenatal visits. A senior pathologist, blinded to exposure status, performed comprehensive pathology examinations on each placenta using a standardized protocol. In multivariable regression models, effects of prenatal exposure were examined on placental size, structure, and presence of infections and meconium.nnnRESULTSnDrinkers reported a binge pattern of heavy drinking, averaging 8.0 drinks/occasion across pregnancy on 1.4 d/wk. 79.6% smoked cigarettes; 22.3% used marijuana; and 17.5% used methamphetamine. Alcohol exposure was related to decreased placental weight and a smaller placenta-to-birthweight ratio. By contrast, methamphetamine was associated with larger placental weight and a larger placenta-to-birthweight ratio. Marijuana was also associated with larger placental weight. Alcohol exposure was associated with increased risk of placental hemorrhage. Prenatal alcohol, drug, and cigarette use were not associated with chorioamnionitis, villitis, deciduitis, or maternal vascular underperfusion. Alcohol and cigarette smoking were associated with a decreased risk of intrauterine passing of meconium, a sign of acute fetal stress and/or hypoxia; methamphetamine, with an increased risk.nnnCONCLUSIONSnThis is the first human study to show that alcohol, methamphetamine, and marijuana were associated with distinct patterns of pathology, suggesting different mechanisms mediating their effects on placental development. Given the growing body of evidence linking placental abnormalities to neurodevelopmental deficits, these findings may be important in the long-term teratogenic effects of prenatal alcohol and drug exposure.

Effects of Prenatal Alcohol Exposure on Testosterone and Pubertal Development

BACKGROUNDnAnimal models have demonstrated fetal alcohol-related disruptions in neuroendocrine function in the hypothalamic-pituitary-gonadal axis and downstream effects on pubertal development and sexual behavior in males and females, but little is known about these effects in humans. This study examined whether prenatal alcohol exposure is associated with alterations in testosterone during adolescence and whether it affects timing of pubertal development.nnnMETHODSnThe sample consisted of 265 African American adolescents from the Detroit Longitudinal Cohort Study for whom testosterone and/or pubertal development data were available. Subjects were offspring of women recruited at their first prenatal clinic visit to over represent moderate-to-heavy alcohol use, including a 5% random sample of low-level drinkers/abstainers. Mothers were interviewed at every prenatal visit about their alcohol consumption using a timeline follow-back approach and about their smoking and drug use and sociodemographic factors. At age 14 years, adolescents provided salivary samples, which were analyzed for testosterone (pg/ml), self-reported Tanner stages for pubertal development, and age at menarche (females).nnnRESULTSnPrenatal alcohol exposure was related to elevated testosterone concentrations for males and females but not to changes in Tanner stages or age at menarche, after controlling for confounders. In regression models stratified by alcohol exposure, the expected relation between testosterone and pubic hair development was seen among males with light-to-no prenatal alcohol exposure, but not among those with moderate-to-heavy prenatal alcohol exposure. This interaction between testosterone and prenatal alcohol exposure was confirmed in multivariable models including an alcohol exposure group × testosterone interaction term and potential confounders.nnnCONCLUSIONSnThis study is the first to show a relation between prenatal alcohol exposure and increased testosterone during adolescence and evidence of decreased testosterone responsiveness in tissues related to pubertal development in humans. Further studies examining androgen receptor expression and other hormonal and cellular factors affecting pubertal development may reveal important mechanisms underlying these teratogenic effects of alcohol exposure.

Heavy Prenatal Alcohol Exposure is Related to Smaller Corpus Callosum in Newborn MRI Scans

BACKGROUNDnMagnetic resonance imaging (MRI) studies have consistently demonstrated disproportionately smaller corpus callosa in individuals with a history of prenatal alcohol exposure (PAE) but have not previously examined the feasibility of detecting this effect in infants. Tissue segmentation of the newborn brain is challenging because analysis techniques developed for the adult brain are not directly transferable, and segmentation for cerebral morphometry is difficult in neonates, due to the latters incomplete myelination. This study is the first to use volumetric structural MRI to investigate PAE effects in newborns using manual tracing and to examine the cross-sectional area of the corpus callosum (CC).nnnMETHODSnForty-three nonsedated infants born to 32 Cape Coloured heavy drinkers and 11 controls recruited prospectively during pregnancy were scanned using a custom-designed birdcage coil for infants, which increases signal-to-noise ratio almost 2-fold compared to the standard head coil. Alcohol use was ascertained prospectively during pregnancy, and fetal alcohol spectrum disorders diagnosis was conducted by expert dysmorphologists. Data were acquired using a multi-echo FLASH protocol adapted for newborns, and a knowledge-based procedure was used to hand-segment the neonatal brains.nnnRESULTSnCC was disproportionately smaller in alcohol-exposed neonates than controls after controlling for intracranial volume. By contrast, CC area was unrelated to infant sex, gestational age, age at scan, or maternal smoking, marijuana, or methamphetamine use during pregnancy.nnnCONCLUSIONSnGiven that midline craniofacial anomalies have been recognized as a hallmark of fetal alcohol syndrome in humans and animal models since this syndrome was first identified, the CC deficit identified here in newborns may support early identification of a range of midline structural impairments. Smaller CC during the newborn period may provide an early indicator of fetal alcohol-related cognitive deficits that have been linked to this critically important brain structure in childhood and adolescence.

Maternal Alcohol Use and Nutrition During Pregnancy: Diet and Anthropometry

BACKGROUNDnDespite known risks of prenatal nutritional deficiencies and studies documenting increased prevalence of poor dietary intake among nonpregnant alcohol abusers, the nutritional status of heavy drinking pregnant women remains largely unstudied. Animal models have found interactions between prenatal ethanol exposure and micronutrients, such as choline, folate, B12, and iron, and human studies have reported that lower maternal weight and body mass confer increased fetal alcohol-related risk.nnnMETHODSnOne hundred and twenty-three heavy drinking Cape Coloured pregnant women and 83 abstaining controls were recruited at their first antenatal clinic visit. At 3 prenatal study visits, each gravida was interviewed about alcohol, smoking, and drug use and weight, height, and arm skinfolds were measured. Dietary intakes of energy, protein, fat, and major micronutrients were assessed from three 24-hour recall interviews.nnnRESULTSnThe majority of women gained less than the recommended 0.42xa0kg/wk during pregnancy. Whereas methamphetamine use was associated with smaller biceps skinfolds, an indicator of body fat, alcohol consumption was not related to any anthropometric indicator. Alcohol was related to higher intake of phosphorus, choline, and vitamins B12 and D. Alcohol, cigarette, and methamphetamine use were related to lower vitamin C intake. Insufficient intake was reported by >85% of women for 10 of 22 key nutrients, and >50% for an additional 3 nutrients.nnnCONCLUSIONSnAlcohol consumption during pregnancy was not associated with meaningful changes in diet or anthropometric measures in this population, suggesting that poor nutrition among drinkers does not confound the extensively reported effects of prenatal alcohol exposure on growth and neurobehavior. The poor gestational weight gain and high rates of insufficient intake for several nutrients in both the alcohol-exposed and control groups are also of public health importance.

Commentary on Day and colleagues : the association between prenatal alcohol exposure and behavior at 22 years of age--adverse effects of risky patterns of drinking among low to moderate alcohol-using pregnant women.

Day and colleagues have presented the first data showing that the behavioral effects of low to moderate prenatal alcohol exposure seen in childhood and adolescence persist into adulthood. Using the Achenbach Adult Self-Report, they found dose-dependent effects of prenatal exposure on internalizing, externalizing, and attention problems that persist in young adults and, thus, appear to be permanent. To date, few studies have attempted to identify thresholds at which prenatal alcohol exposure is harmful, although the animal literature suggests that even 1 to 2 binge episodes can result in adverse effects in the offspring. Four prospective longitudinal studies have reported adverse effects at what can be characterized as moderate exposure levels based on NIAAA criteria, but moderate drinking women often concentrate their alcohol use on 1 to 2 days per week, thereby engaging in binge drinking. In this study, binge drinking was not a strong predictor of adverse outcome when average daily dose was held constant, a conclusion that the authors note runs counter to studies that have reported that binge drinking has a greater effect. This inconsistency may be due to the difficulty of allocating variance that is shared (overlapping) between average daily dose and binge drinking (i.e., dose/occasion). Data from laboratory animal studies, in which dosage can be manipulated experimentally, demonstrate that a higher dose per occasion, the key feature of binge drinking, leads to more severe adverse effects. Day and colleagues findings of adverse effects at low levels of exposure provides clear evidence that there is no safe level of drinking during pregnancy and that, even at low levels, drinking results in irreversible behavioral impairment. On the other hand, given the evidence from the animal and most human studies, it is important for all women who drink during pregnancy, even at light to moderate levels, to recognize that minimizing their intake per occasion and refraining from binge drinking can reduce risk to the fetus.