Pathways from prenatal cocaine exposure to adult substance use and behavior

This is a report from the most recent adult follow-up of the longest running cohort study of prenatal cocaine exposure (PCE), in which women were enrolled prenatally and offspring were assessed in infancy, childhood, adolescence, and young adulthood. In previous studies, PCE was linked to offspring behavior problems such as early substance use and externalizing behavior problems. The current analyses examine pathways from PCE to behavioral outcomes in offspring at the 25-year assessment. Prenatal cocaine exposure was moderate in this cohort; most women decreased or discontinued use after the first trimester. During the first and third trimesters, 38% and 11% used cocaine, respectively. This represents the most common pattern of PCE in non-treatment samples. At this phase, the adult offspring were, on average, 27.3 years old (range = 25-30), had 13.4 years of education, 83% were employed, 55% were Black, and 55% were female. Offspring who were exposed to cocaine during the first trimester were significantly more likely to use marijuana in the past year, report more arrests, and have poorer scores on a decision-making task, controlling for other prenatal substance exposure, demographic, and socioeconomic factors. In mediation analyses, there were indirect pathways from PCE to current marijuana use through early initiation of marijuana use and 21-year marijuana use, and through 15-year status offenses and 21-year marijuana use. There was also an indirect pathway from PCE to lifetime arrests through early initiation of marijuana use and 21-year Conduct Disorder, although the direct pathway from PCE to arrests also remained significant. These findings are consistent with those from previous phases and are an indication that there are detrimental associations with PCE that persist across developmental stages and into adulthood.

Long-term effects of prenatal cannabis exposure: Pathways to adolescent and adult outcomes

With the increased prevalence, potency, and acceptability of cannabis use during pregnancy, it is important to understand the developmental effects of prenatal cannabis exposure (PCE). This review discusses methodological considerations for studies of PCE, including the assessment of exposures, covariates, and outcomes, and reviews findings from prospective, longitudinal studies of PCE. There is some evidence for associations between PCE and restricted growth at birth, but not for long-term effects on growth. PCE appears to have subtle yet enduring effects on memory and achievement in children and adolescents. Despite differences in sample demographics and measurement, there are remarkably consistent effects of PCE on externalizing behaviors, such as delinquency and substance use, which persist into adulthood. Longitudinal analyses demonstrate the importance of early cannabis initiation for pathways between PCE and adult functioning, including substance use and abuse, memory deficits, and psychotic symptoms. Animal studies demonstrate direct effects on the development of the brain via activation of endogenous endocannabinoid systems. Cannabis-induced activation of the endocannabinoid system causes alterations in the release of neurotransmitters and the modulation of brain plasticity in neural pathways that underlie cognition, motivation, and behavior regulation. Future research should consider cannabis use before pregnancy, the timing and route of exposure, polysubstance exposures, and inter-generational effects.

A longitudinal study of the impact of marijuana on adult memory function: Prenatal, adolescent, and young adult exposures

More Americans are using marijuana than in previous decades but there are concerns over its long-term impact on cognitive functioning, especially memory. The literature on marijuana use and cognitive functioning is mixed, with some studies showing recovery of functioning upon abstinence from the drug and others showing long-term effects that persist. The latter seems especially true for individuals who initiate marijuana at a younger age and engage in more chronic patterns of use. The goal of the current study is to use prospectively collected data on young adults from a prenatal cohort to determine if there is an effect of early and/or current marijuana use on young adult memory, controlling for prenatal exposure to marijuana use, childhood memory deficits, and other significant covariates of memory functioning. At the 22-year follow-up phase of the Maternal Health Practices and Child Development (MHPCD) study, 524 young adults (58% Black, 42% White, 52% female) completed the Wechsler Memory Scale-III. Multiple regression analyses and structural equation modeling were used to determine the effect of marijuana exposure during gestation, early adolescence, and young adulthood on young adult memory function. Results indicated that initiating marijuana use before age 15 placed young adults at greater risk of memory deficits, even after controlling for childhood memory and current marijuana use. First trimester marijuana exposure also indirectly predicted young adult memory function via childhood memory deficits and early initiation of marijuana. These findings highlight the risk of prenatal marijuana exposure and early initiation of marijuana for long-term memory function in adulthood.

An examination of the association between prenatal cocaine exposure and brain activation measures of arousal and attention in young adults: An fMRI study using the Attention Network Task

Prenatal drug exposure, including cocaine, alcohol, marijuana, and tobacco, is associated with deficits in behavioral regulation and attention. Using fMRI, the objective of this study was to characterize the association between prenatal cocaine exposure (PCE) and the underlying neural substrates associated with behavioral outcomes of attention. Forty-seven young adults were recruited for this study from the ongoing Maternal Health Practices and Child Development (MHPCD) Project, a longitudinal study of the effects of PCE on growth, behavior, and cognitive function. Three groups were compared: 1) prenatal exposure to cocaine, alcohol, marijuana, and tobacco (CAMT, n = 15), 2) prenatal exposure to alcohol, marijuana, and tobacco (AMT, n = 17), and 3) no prenatal exposure to drugs (Controls, n = 15). Subjects were frequency matched on gender, race, handedness, and 15-year IQ. This study used the theoretical model proposed by Posner and Peterson (1990), which posits three dissociable components of attention: alerting, orienting, and executive attention. Subjects completed a functional MRI (fMRI) scan while performing the Attention Network Task, a validated neuroimaging measure of the 3-network model of attention. Behavioral and fMRI data revealed no associations between PCE and task accuracy, speed of processing, or activation in key brain regions associated with each of the attention networks. The results of this study show that any subtle differences in brain function associated with PCE are not detectable using the ANT task and fMRI. These results should be interpreted in the context of other studies that have found associations between PCE and arousal with emotionally arousing stimuli, compared to this study that found no associations using emotionally neutral stimuli.

Effects of prenatal cigarette smoke exposure on neurobehavioral outcomes in 10-year-old children of adolescent mothers

In this prospective study, adolescent mothers (mean age=16; range=12-18; 70% African-American) were interviewed about their tobacco use during pregnancy. When their children were ten, mothers reported on their child's behavior and the children completed a neuropsychological battery. We examined the association between prenatal cigarette smoke exposure (PCSE) and offspring neurobehavioral outcomes on data from the 10-year phase (n=330). Multivariate regression analyses were conducted to test if PCSE predicted neurobehavioral outcomes, adjusting for demographic characteristics, maternal psychological characteristics, prenatal exposure to other substances, and exposure to environmental tobacco smoke. Independent effects of PCSE were found. Exposed offspring had more delinquent, aggressive, and externalizing behaviors (CBCL). They were more active (Routh, EAS, and SNAP) and impulsive (SNAP) and had more problems with peers (SNAP). On the Stroop test, deficits were observed on the more complex interference task that requires both selective attention and response inhibition. The significant effects of PCSE on neurobehavioral outcomes were found for exposure to as few as 10 cigarettes per day. Most effects were found from first trimester PCSE exposure. These results are consistent with results from an earlier assessment when the children were age 6, demonstrating that the effects of prenatal tobacco exposure can be identified early and are consistent through middle childhood.

Body size and intelligence in 6-year-olds: are offspring of teenage mothers at risk?

OBJECTIVES

Children born to teenage mothers are at risk for more physical and cognitive problems than those born to adult mothers. Our objective was to examine differences in size and intelligence between two cohorts of offspring born to adolescent (n = 357) and adult mothers (n = 668) who attended the same prenatal clinic.

METHODS

Two prospective study cohorts assessed children from gestation through age 6 years. The adult cohort was studied in the mid-1980's and the teen cohort was evaluated in the mid-1990's. Both samples were of low socio-economic status. The same study design and measures allowed us to adjust for the covariates of size and IQ.

RESULTS

Offspring of adolescent mothers had a significantly smaller mean head circumference (5 mm) (HC) and higher body mass index (BMI) than offspring of adult mothers. Offspring of adolescent mothers scored significantly lower than the offspring of adult mothers on the Stanford-Binet (SBIS) composite score (4 points), and the quantitative (6.2 points), verbal reasoning (4.8 points), and short-term memory (3.9 points) area scores. Additional predictors of child IQ were maternal IQ, home environment, race, and number of siblings. When child HC was entered into our final regression model for the SBIS, maternal age and HC significantly predicted the composite score, the verbal reasoning, and short-term memory area scores. A 1 cm decrease in HC predicted a 1 point decrease in the SBIS composite score.

CONCLUSIONS

Compared to offspring of adult women, children of adolescent mothers have lower mean scores on cognitive measures, smaller head circumference, and higher BMI. These differences were significant after adjusting for differences between the two groups. Adolescent mothers and their children would benefit from interventions such as parenting support, education about nutritional needs, and advice on enriching the environments of their children.

Verbal and Visuospatial Learning and Memory Function in Children With Moderate Prenatal Alcohol Exposure

BACKGROUND

This study investigated the effects of moderate prenatal alcohol exposure on learning and memory in 14-year-old adolescents. The Children's Memory Scale was used to assess learning and memory function in the verbal/auditory and visual/spatial domains. In addition, both short- and long-term memory function were assessed.

METHODS

Data were collected as part of the Maternal Health Practices and Child Development Project, a longitudinal study including 580 children and their mothers. Women were assessed during each trimester of pregnancy and with their children from birth to 16 years of age. At age 14, memory function was evaluated using the Children's Memory Scale, an assessment tool that measures learning and immediate and delayed memory function in the verbal and visual-spatial domains.

RESULTS

Prenatal alcohol exposure during the first trimester predicted deficits in learning, short-term memory, and long-term memory, specifically in the verbal domain. Deficits in performance were specific to learning and memory of word-pairs. In addition, deficits in memory were mediated by learning performance.

CONCLUSIONS

Results demonstrated that prenatal alcohol exposure lead to deficits in encoding processes as indicated by deficits in verbal learning. Initial deficits in acquisition were responsible for deficits in immediate and delayed recall of verbal information in children who were exposed to alcohol during pregnancy but did not have fetal alcohol syndrome.

Prenatal tobacco effects on neuropsychological outcomes among preadolescents

This study evaluated the relationships between maternal smoking during pregnancy and 10-year-old children's performance on measures of learning, memory, and problem-solving. In this prospective cohort study, mothers were recruited from an urban prenatal clinic in 1982 and 1983 and observed from their fourth prenatal month until the time of the study. At the 10-year visit, 593 children and mothers were evaluated. The prevalence of tobacco use was high in this cohort: 54.3%, 53.3%, and 60% of the women smoked in the first trimester, third trimester, and 10-year assessment, respectively. After controlling statistically for other prenatal substance use, current tobacco, other substance use variables, and multiple sociodemographic covariates, prenatal tobacco exposure was significantly associated with deficits in learning and memory. Specifically, prenatal tobacco exposure was associated with deficits in verbal learning and design memory, as well as slowed responding on a test of eye-hand coordination. In addition, these children demonstrated a reduced ability for flexible problem solving and more impulsivity, as indicated by an increase in perseverative responses on a card-sorting test. Prenatally exposed children did not show attention deficits or increased activity on a continuous performance test.

The behavioral teratogenic potential of fenbendazole: a medication for pinworm infestation

Fenbendazole (FBZ) is a benzimidazole currently used for anthelmintic treatment of pinworm populations in numerous animal species although it is not currently approved for laboratory rodents in the U.S. It has received considerable interest for treating rodent populations due to its low toxicity, wide safety margin and apparent absence of gross teratogenic effects. The purpose of this study was to assess the behavioral teratogenic potential of FBZ. Pregnant rats were administered either FBZ-medicated feed at a therapeutic level or normal rat chow throughout pregnancy and gestation. FBZ had no effect on pregnancy indicators such as maternal weight gain or water consumption, number of pups born or pup birth weights. Offspring were examined in a variety of paradigms including righting reflex, negative geotaxis, running wheel activity, Morris water maze (MWM) performance and digging maze performance. FBZ offspring did show delayed righting reflex, some modest changes in locomotor activity in a running wheel and minor alterations in performance during the probe session of the MWM relative to controls. However, the effects of FBZ on behavior were subtle and many of the behaviors examined were unaffected. These results suggest that FBZ may be an effective and relatively safe anthelmintic treatment for use in breeding colonies.

The effects of neonatal ethanol and/or cocaine exposure on isolation-induced ultrasonic vocalizations

Isolation-induced ultrasonic vocalizations (USVs) are emitted by young rat pups when isolated from their dam and conspecifics. These USVs play an important role in maternal/offspring interactions, and have been used as an indicator of response to stress and isolation. This study examined the effects of neonatal ethanol and/or cocaine exposure on USVs in neonatal rats. The neonatal exposure paradigm serves as a model for the "human third trimester of pregnancy" in terms of CNS development. There were five treatment groups including an artificially reared (AR) ethanol-exposed group (6 g/kg/day), an AR cocaine-exposed group (60 mg/kg/day), an AR ethanol- and cocaine-exposed group (6 g/kg/day+60 mg/kg/day), an AR isocaloric control, and a normally reared control. Both groups that received ethanol took longer to vocalize, and displayed fewer vocalizations than non-ethanol-exposed pups when tested on clean bedding (Experiment 1) or on chips from the nest of a lactating dam (Experiment 2). These results suggest that neonatal ethanol exposure alters the pup's immediate response to isolation. This could have direct effects on maternal/infant interactions, and might help explain some of the long-term effects of ethanol exposure on social behaviors.

The behavioral response to novelty is altered in rats neonatally exposed to cocaine

It has recently been suggested that the effects of in utero cocaine exposure may result in subtle deficits related to a challenging environment, including exposure to novelty or stress. This study used a neonatal drug-exposure model to examine the behavioral response to a novel environment in rodents. Subjects were artificially reared (AR) from postnatal Days 4-10. There were four treatment groups; AR 40 mg/kg/day cocaine, AR 20 mg/kg/day cocaine, AR control group receiving no drug, and a normally reared control. In Experiment 1, subjects were tested for their preference of maternal home-cage or clean wood-chip odors in a T-maze on postnatal Day 15. Subjects from all treatment groups preferred the maternal odor. In Experiment 2, subjects were habituated to four familiar odors and tested with a novel odor in an open field (postnatal Days 16-21). Neonatal exposure to 20 mg/kg/day cocaine led to an overall increase in exploratory behavior during testing, whereas 40 mg/kg/day did not, supporting the hypothesis that developmental exposure to cocaine at some doses may alter the offspring's response to a changing environment.

The effects of neonatal cocaine exposure on a play-rewarded spatial discrimination task in juvenile rats

This study examined the effects of neonatal cocaine exposure on the rewarding properties of play in a modified T-maze. Animals were artificially reared from postnatal day (PND) 4-9 with drug concentrated in four daily feeds. There were four treatment groups, 40 mg/kg/day cocaine, 20 mg/kg/day cocaine, an artificially reared control and a surgery control. From PND 38-42, subjects were tested with a food reward (EXP 1) or a play reward (EXP 2). No deficits in learning were seen when the reward was food. The 20 mg/kg/day cocaine group, however, showed impaired learning and altered play behavior when the reward was access to a play partner. Neonatal cocaine exposure thus appears to differentially affect learning based on the type of reward presented.

The effects of clonidine on rat pups neonatally exposed to cocaine

This study examined the effects of neonatal cocaine exposure on responsivity to the alpha2 noradrenergic agonist clonidine in 11-day-old rat pups. On postnatal day (PND) 4 neonatal rats were assigned to one of four treatment groups: artificially reared (AR) receiving 40 mg/kg/day cocaine hydrochloride, AR receiving 20 mg/kg cocaine, AR control receiving no drug, and a normally reared control group. Pups were maintained in this fashion from PND 4 to 9 and received no drug on PND 10. On PND 11 subjects received an IP injection of either 0, 0.25, or 1.0 mg/kg clonidine hydrochloride and were observed for locomotor activity and wall-climbing during a 15-min test session. Subjects exposed to the 40 mg/kg dose of cocaine demonstrated an enhanced sensitivity to the locomotor stimulating effects of clonidine relative to both control groups. This cocaine-related enhanced sensitivity was not observed on the wall-climbing measure. All groups showed evidence of wall-climbing, although this behavior was somewhat dampened among AR groups. The 20 mg/kg cocaine-exposed males also took longer to display wall-climbing behavior than their respective females regardless of clonidine dose, although this sex difference was not apparent for any other treatment group. These findings suggest that neonatal cocaine exposure may alter response of the noradrenergic system.