Stronger Working Memory Reduces Sexual Risk Taking in Adolescents, Even After Controlling for Parental Influences.

This study examined the prospective influence of adolescent working memory (WM) on changes in impulsivity and sexual risk taking and assessed whether this relation could be explained by confounding effects of parental influences. Data from 360 community adolescents (Mage  = 13.5 ± 0.95 years; 52% female; 56% non-Hispanic White; low-mid socioeconomic status (SES); recruited from Philadelphia area in 2004-2005) were analyzed using structural equation modeling to predict changes in impulsivity and sexual risk taking over a 2-year follow-up, using baseline assessments of WM, parental monitoring, parental involvement, and SES. Stronger WM predicted reduced involvement in sexual risk taking at follow-up, effects channeled through changes in impulsivity dimensions of "acting without thinking" and "inability to delay gratification." Parental variables had a protective influence on adolescent impulsivity and risk involvement, but the effects of WM operated independently of parental influences.

Experimentation versus progression in adolescent drug use: A test of an emerging neurobehavioral imbalance model.

Based on an emerging neuroscience model of addiction, this study examines how an imbalance between two neurobehavioral systems (reward motivation and executive control) can distinguish between early adolescent progressive drug use and mere experimentation with drugs. Data from four annual assessments of a community cohort (N = 382) of 11- to 13-year-olds were analyzed to model heterogeneity in patterns of early drug use. Baseline assessments of working memory (an indicator of the functional integrity of the executive control system) and three dimensions of impulsivity (characterizing the balance between reward seeking and executive control systems) were used to predict heterogeneous latent classes of drug use trajectories from early to midadolescence. Findings revealed that an imbalance resulting from weak executive control and heightened reward seeking was predictive of early progression in drug use, while heightened reward seeking balanced by a strong control system was predictive of occasional experimentation only. Implications of these results are discussed in terms of preventive interventions that can target underlying weaknesses in executive control during younger years, and potentially enable at-risk adolescents to exercise greater self-restraint in the context of rewarding drug-related cues.

Working memory ability predicts trajectories of early alcohol use in adolescents: the mediational role of impulsivity.

AIMS: (i) To evaluate the role of pre-existing weakness in working memory ability (WM) as a risk factor for early alcohol use as mediated by different forms of impulsivity and (ii) to assess the adverse effects of progressive alcohol use on variations in WM over time. DESIGN, SETTING AND PARTICIPANTS: A community sample of 358 adolescents [48% males, mean(age) (baseline) = 11.4 ± 0.87 years] from a longitudinal cohort design, assessed annually over 4 consecutive years with less than 6% attrition. MEASUREMENTS: Repeated assessments were conducted for the following key variables: WM (based on performance on four separate tasks), frequency of alcohol use (AU) and three forms of impulsivity, namely sensation seeking (SS), acting without thinking (AWT) and delay discounting (DD). Latent growth curve modeling procedures were used to identify individual trajectories of change for all key variables. FINDINGS: Weakness in WM (at baseline) predicted significantly both concurrent alcohol use and increased frequency of use over the four waves (P < 0.05). This effect was entirely mediated by two forms of impulsivity, AWT and DD, both of which were characterized by underlying weakness in WM. No individual variation was observed in the slopes of WM, which suggests that individual variations in alcohol use were not associated with changes in WM in our early adolescent sample. CONCLUSIONS: Early adolescent alcohol use may be a consequence of (pre-existing) weaknesses in working memory (WM) rather than a cause of it. Efforts to reduce early alcohol use should consider the distinct roles of different impulsivity dimensions, in addition to WM, as potential targets of intervention.

Suicidal ideation and self-harm behavior in a community sample of preadolescent youth: a case-control study.

OBJECTIVE: Research has focused on understanding risk factors associated with suicidal ideation and self-harm behaviors in older youth, but less is known regarding these behaviors in preadolescents. We examined characteristics associated with suicidal ideation and self-harm behavior in youth aged 10-13 years. DESIGN/METHODS: A community sample of 387 youth was enrolled in a prospective study assessing precursors of risk behaviors. Twenty-three subjects endorsing items regarding suicidal ideation or self-harm behaviors (Achenbach's Youth Self-Report) (endorsers) were matched with 23 non-endorsers. Groups were compared on problem behaviors, impulsivity, neurocognitive function, risk behaviors, and other variables. RESULTS: Endorsers had higher levels of impulsivity, were more likely in borderline/clinical range on 5 of 8 Youth Self-Report Syndrome scales, and reported more risk taking. Endorsers and non-endorsers were similar in neurocognitive function. More non-endorsers were on stimulants, but groups were similar in parental monitoring and parental report of behavioral/emotional issues, socioeconomic status, and marital status. CONCLUSION: In this study, preadolescent endorsers report significantly more problem behaviors than non-endorsers. However, parental monitoring and parent report of problems were similar between groups. Given these findings, we suggest that at-risk youth may be underrecognized at young ages.

Early adolescent sexual debut: the mediating role of working memory ability, sensation seeking, and impulsivity.

Although deficits in working memory ability have been implicated in suboptimal decision making and risk taking among adolescents, its influence on early sexual initiation has so far not been examined. Analyzing 2 waves of panel data from a community sample of adolescents (N = 347; Mean age[baseline] = 13.4 years), assessed 1 year apart, the present study tested the hypothesis that weak working memory ability predicts early sexual initiation and explored whether this relationship is mediated by sensation seeking and 2 forms of impulsivity, namely acting-without-thinking and temporal discounting. The 2 forms of impulsivity were expected to be positively associated with early sexual initiation, whereas sensation seeking was hypothesized to be unrelated or to have a protective influence, due to its positive association with working memory. Results obtained from structural equation modeling procedures supported these predictions and in addition showed that the effects of 3 prominent risk factors (Black racial identity, low socioeconomic background, and early pubertal maturation) on early sexual initiation were entirely mediated by working memory and impulsivity. The findings are discussed in regard to their implications for preventing early sexual onset among adolescents.

Is executive cognitive function associated with youth gambling?

Our objectives for this report were to identify trajectories of youth gambling behavior, and to examine their relation to executive cognitive function (ECF) and associated problem behaviors. Philadelphia school children, enrolled at ages 10-12 years (n = 387; 49% male), completed three annual assessments of risk behaviors, ECF, impulsivity, problem behaviors and demographics. Across ages 10-15 years, using methods from Nagin et al., two groups were identified: Early Gamblers (n = 111) initiated early and continued in later assessments, and Later Gamblers (n = 276) initiated at later ages and gambled less. Betting money on cards and sports were the most frequently reported gambling behaviors. Using gambling group as outcome, final backward selection logistic regression model showed Early Gamblers are more likely male (P = 0.001), report more active coping (P = 0.042), impulsive behaviors (P ≤ 0.008), and have friends who gamble (P = 0.001). Groups were similar in ECF, parental monitoring, marital status, SES, and race. Early Gamblers had higher incidence of problem behaviors and drug use (all P ≤ 0.006). Two gambling groups were identified in early adolescence with Early Gamblers showing higher levels of impulsivity and comorbid problems but similar levels of ECF compared to Late Gamblers. As more gambling groups are identified through later adolescence, ECF may emerge as a relevant precursor of problem gambling at this later time.

Does adolescent risk taking imply weak executive function? A prospective study of relations between working memory performance, impulsivity, and risk taking in early adolescence.

Studies of brain development suggest that the increase in risk taking observed during adolescence may be due to insufficient prefrontal executive function compared to a more rapidly developing subcortical motivation system. We examined executive function as assessed by working memory ability in a community sample of youth (n = 387, ages 10 to 12 at baseline) in three annual assessments to determine its relation to two forms of impulsivity (sensation seeking and acting without thinking) and a wide range of risk and externalizing behavior. Using structural equation modeling, we tested a model in which differential activation of the dorsal and ventral striatum produces imbalance in the function of these brain regions. For youth high in sensation seeking, both regions were predicted to develop with age. However, for youth high in the tendency to act without thinking, the ventral striatum was expected to dominate. The model predicted that working memory ability would exhibit (1) early weakness in youth high in acting without thinking but (2) growing strength in those high in sensation seeking. In addition, it predicted that (3) acting without thinking would be more strongly related to risk and externalizing behavior than sensation seeking. Finally, it predicted that (4) controlling for acting without thinking, sensation seeking would predict later increases in risky and externalizing behavior. All four of these predictions were confirmed. The results indicate that the rise in sensation seeking that occurs during adolescence is not accompanied by a deficit in executive function and therefore requires different intervention strategies from those for youth whose impulsivity is characterized by early signs of acting without thinking.

Adolescents with and without gestational cocaine exposure: Longitudinal analysis of inhibitory control, memory and receptive language.

Preclinical studies of gestational cocaine exposure (GCE) show evidence of changes in brain function at the anatomical, physiological, and behavioral levels, to include effects on developing dopaminergic systems. In contrast, human studies have produced less consistent results, with most showing small effects or no effects on developmental outcomes. Important changes in brain structure and function occur through adolescence, therefore it is possible that prenatal cocaine exposure has latent effects on neurocognitive (NC) outcome that do not manifest until adolescence or young adulthood. We examined NC function using a set of 5 tasks designed to tap 4 different systems: inhibitory control, working memory, receptive language, and incidental memory. For each NC task, data were collected longitudinally at ages 12, 14.5 and 17 years and examined using generalized estimating equations. One hundred and nine children completed at least two of the three evaluations. Covariates included in the final model were assessment number, gender, participant age at first assessment, caregiver depression, and two composites from the Home Observation for Measurement of the Environment (HOME), Environmental Stimulation and Parental Nurturance. We found no cocaine effects on inhibitory control, working memory, or receptive language (p=0.18). GCE effects were observed on incidental face memory task (p=0.055), and GCE by assessment number interaction effects were seen on the incidental word memory task (p=0.031). Participant performance on inhibitory control, working memory, and receptive language tasks improved over time. HOME Environmental Stimulation composite was associated with better receptive language functioning. With a larger sample size smaller differences between groups may have been detected. This report shows no evidence of latent effects of GCE on inhibitory control, working memory, or receptive language. GCE effects were observed on the incidental face memory task, and GCE by assessment number interaction effects was seen on the incidental word memory task.

Early parental care is important for hippocampal maturation: evidence from brain morphology in humans.

The effects of early life experience on later brain structure and function have been studied extensively in animals, yet the relationship between childhood experience and normal brain development in humans remains largely unknown. Using a unique longitudinal data set including ecologically valid in-home measures of early experience during childhood (at age 4 and 8 years) and high-resolution structural brain imaging during adolescence (mean age 14 years), we examined the effects on later brain morphology of two dimensions of early experience: parental nurturance and environmental stimulation. Parental nurturance at age 4 predicts the volume of the left hippocampus in adolescence, with better nurturance associated with smaller hippocampal volume. In contrast, environmental stimulation did not correlate with hippocampal volume. Moreover, the association between hippocampal volume and parental nurturance disappears at age 8, supporting the existence of a sensitive developmental period for brain maturation. These findings indicate that variation in normal childhood experience is associated with differences in brain morphology, and hippocampal volume is specifically associated with early parental nurturance. Our results provide neuroimaging evidence supporting the important role of warm parental care during early childhood for brain maturation.

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.

Executive cognitive functions and impulsivity as correlates of risk taking and problem behavior in preadolescents.

Initiation of drug use and other risky behavior in preadolescence is associated with poor developmental outcomes. In this research, we examine models that ascribe the trajectory to (a) weak executive cognitive function (ECF), (b) early manifestation of externalizing problems, or (c) heightened levels of trait impulsivity. We test the explanatory power of these factors in a structural equation model with a community sample of 387 preadolescents ages 10-12 years. Participants were tested with a computerized battery of tasks to assess three facets of ECF (working memory, cognitive control, and reward processing) as well as with an audio assisted computerized self-interview to obtain reports of impulsivity and risk behaviors (use of cigarettes and alcohol as well as engaging in fighting and gambling for money) and a self-administered questionnaire to assess externalizing and internalizing problems. The best fitting model explained both early risk taking and externalizing symptoms as the result of individual differences in impulsivity. Although no ECF was directly related to risk taking, working memory and one measure of reward processing performance (reversal learning) were inversely related to impulsivity. The results are discussed in regard to theories of early risk taking with particular focus on the potential relation between ECF and impulsive behavior tendencies and the implications for early intervention to prevent the dysfunctional trajectory associated with early risk behavior.

Environmental stimulation, parental nurturance and cognitive development in humans.

The effects of environmental stimulation and parental nurturance on brain development have been studied extensively in animals. Much less is known about the relations between childhood experience and cognitive development in humans. Using a longitudinally collected data set with ecologically valid in-home measures of childhood experience and later in-laboratory behavioral measures of cognitive ability, we were able to test hypotheses concerning the effects of environmental stimulation and parental nurturance. A double dissociation was found: On the one hand, there was a selective relation between parental nurturance and memory development, consistent with the animal literature on maternal buffering of stress hormone effects on hippocampal development. On the other hand, there was a selective relation between environmental stimulation and language development. The relevance of these findings to socioeconomic gradients in cognitive ability is discussed.

Gambling initiation in preadolescents.

Gambling has increased in the past decade, with growing opportunities for initiation by adolescents. More limited data, however, are available regarding gambling in preadolescents. In the investigation reported here, gambling for money was the most common risk behavior in 10- to 12-year-olds. Gamblers were more likely to be white, have tried alcohol, have positive affect toward gambling, and have friends who gamble.

Functional magnetic resonance imaging and working memory in adolescents with gestational cocaine exposure.

OBJECTIVE: To assess the effect of gestational cocaine exposure on the prefrontal cortex (PFC) with functional magnetic resonance imaging (fMRI). STUDY DESIGN: Using an n-back task, we obtained fMRI with a 3T Siemens scanner on 49 adolescents, 25 who were exposed to cocaine and 24 who were not exposed. The primary outcome was PFC activation during task performance. Five functionally derived regions of interest (ROI) were defined; in addition, 2 a priori anatomical ROIs were generated for Brodmann regions 10 and 46. RESULTS: Of the 49 adolescents who underwent imaging, data from 17 who were exposed to cocaine and 17 who were not exposed were in the final analysis. Groups had similar performance on the n-back task (P >/= .4), with both showing a fewer number of correct responses on the 2-back than the 1-back (P < .001), indicating increased demands on working memory with greater task difficulty. In functionally derived ROIs, imaging results showed increased activation for both groups in the 2-back versus the 1-back condition. In anatomical ROIs, both groups showed greater activation in the 2-back versus the 1-back condition, with activation in the non-exposed group proportionally greater for the left prefrontal region (P = .05). CONCLUSION: In this sample of adolescents, participants who were exposed to cocaine and participants who were not exposed were similar in performance on an executive function task and in fMRI activation patterns during task performance.

Effects of heavy in utero cocaine exposure on adolescent caudate morphology.

We assess the effects of in utero cocaine and polysubstance exposure on the adolescent caudate nucleus through high-resolution magnetic resonance imaging. Cocaine exposure may compromise the developing brain through disruption of neural ontogeny in dopaminergic systems, effects secondary to fetal hypoxemia, or altered cerebrovascular reactivity. Cocaine exposure may also lead to neonatal lesions in the caudate. However, long-term or latent effects of intrauterine cocaine exposure are rarely found. We use T(1)-weighted magnetic resonance imaging to quantify caudate nucleus morphology in matched control and exposed groups. The literature suggests that in utero cocaine exposure consequences in adolescents may be subtle, or masked by other variables. Our comparison focuses on contrasting the control group with high-exposure subjects (mothers who reported 2 median of 117 days of cocaine use during pregnancy; 82% tested positive for cocaine use at term). We use advanced image registration and segmentation tools to quantify left and right caudate morphology. Our results indicate that the caudate is significantly larger in controls versus subjects (P < 0.0025), implying cocaine exposure-related detriments to the dopaminergic system. The right (P < 0.025) and left (P < 0.035) caudate, studied independently, show the same significant trend. Permutation testing and the false discovery rate were used to assess significance.

Childhood poverty: specific associations with neurocognitive development.

Growing up in poverty is associated with reduced cognitive achievement as measured by standardized intelligence tests, but little is known about the underlying neurocognitive systems responsible for this effect. We administered a battery of tasks designed to tax-specific neurocognitive systems to healthy low and middle SES children screened for medical history and matched for age, gender and ethnicity. Higher SES was associated with better performance on the tasks, as expected, but the SES disparity was significantly nonuniform across neurocognitive systems. Pronounced differences were found in Left perisylvian/Language and Medial temporal/Memory systems, along with significant differences in Lateral/Prefrontal/Working memory and Anterior cingulate/Cognitive control and smaller, nonsignificant differences in Occipitotemporal/Pattern vision and Parietal/Spatial cognition.

School performance of children with gestational cocaine exposure.

OBJECTIVE: To document school performance (pass/fail, grade point average, reading level, standardized test scores, absences) of cocaine-exposed and control children. DESIGN: A total of 135 children (62 with gestational cocaine exposure and 73 without), who were enrolled at birth, followed prospectively and have completed the fourth grade, were evaluated using report card data, standardized test results, teacher and parent report, and natal and early childhood data. Successful grade progression was defined as completing grades 1 through 4 without being retained. RESULTS: Cocaine-exposed (cocaine-exposed presented first) and control children were similar in school performance: successful grade progression (71% vs. 84%), Grade Point Average (2.4+/-0.8 vs. 2.6+/-0.7), reading below grade level (30% vs. 28%) and standardized test scores below average (reading [32% vs. 35%], math [57% vs. 44%], science [39% vs. 36%]); all p > or = 0.10. Children with successful progression, regardless of cocaine exposure, had higher Full Scale Intelligence Quotient and better home environments. CONCLUSION: In this inner-city cohort, cocaine-exposed and control children had similar poor school performance. Better home environment and higher Intelligence Quotient conferred an advantage for successful grade progression, regardless of gestational cocaine exposure.

Attentional functioning and impulse control in cocaine-exposed and control children at age ten years.

Children with gestational cocaine exposure may be at risk of difficulties in attentional functioning and impulse control. We administered the Gordon Diagnostic System and subtests of the Halstead-Reitan Battery to inner-city children with (COC) and without (CON) gestational cocaine exposure at age 10 years. Subtle differences were found between groups, with differences in Gordon Delay (Efficiency Ratio) and Gordon Distractibility (Total Commissions). With these two exceptions, children had similar performance, with both groups performing poorly. Attentional functioning and impulse control were also assessed in school. Teachers did not distinguish between COC and CON, although both groups presented behavioral problems. We conclude that gestational cocaine exposure may be associated with subtle problems in attention and impulse control, putting exposed children at higher risk of developing significant behavioral problems as cognitive demands increase.