Increased risk of attention-deficit/hyperactivity disorder in adolescents with high salivary levels of copper, manganese, and zinc.

Exposure to toxic heavy metals has been associated with the development of attention-deficit/hyperactivity disorder (ADHD). However, fewer studies have examined the associations between abnormal levels of essential trace metals and ADHD, and none have done so using saliva. We investigated whether salivary metals were associated with ADHD in adolescents aged 12 from the Family Life Project (FLP) using a nested case-control study design that included 110 adolescents who met diagnostic criteria for inattentive (ADHD-I), hyperactive-impulsive (ADHD-H), or combined type ADHD (ADHD-C) (cases) and 173 children who did not (controls). We used inductively coupled plasma optical emission spectrophotometry to measure chromium, copper, manganese, and zinc in saliva samples. We employed logistic regression models to examine associations between quartile levels of individual metals and ADHD outcomes by subtype. Salivary copper levels were significantly associated with increased odds of any ADHD diagnosis (OR = 3.31, 95% CI: 1.08-10.12; p = 0.04) and with increased odds of ADHD-C diagnosis (OR = 8.44, 95% CI: 1.58-45.12; p = 0.01). Salivary zinc levels were significantly associated with increased odds of ADHD-C diagnosis (OR = 4.06, 95% CI: 1.21-13.69; p = 0.02). Salivary manganese levels were also significantly associated with increased odds of ADHD-C diagnosis (OR = 5.43, 95% CI: 1.08-27.27, p = 0.04). This is the first study using saliva to assess metal exposure and provide a potential link between salivary levels of copper, manganese, and zinc and ADHD diagnoses in adolescents. Public health interventions focused on metal exposures might reduce ADHD incidence in low-income, minority communities.

Short report: Improving motor competence skills in early childhood has corollary benefits for executive function and numeracy skills.

Previous studies have documented that individual differences in fine and gross motor skills are associated with executive function (EF) skills. This study used an experimental design to test whether participating in cognitively challenging motor skills activities was causally related to improvements in motor skills and two key indicators of school readiness: executive function and early numeracy skills. The motor skill program involved fine and gross motor game-like activities that were delivered in a small group format. Activities were socially engaging and progressively challenged children based on their motor competencies. Fifty-three preschool-aged children participated in 16 motor skill sessions across 8 weeks. There were significant treatment effects for all outcomes, such that children in the treatment condition exhibited significant improvements in motor, EF, and early numeracy skills, compared to their peers in the waitlist control condition. Treatment effects on EF skills were stronger for inhibitory control than working memory. Improvements in numeracy were most pronounced for children with initially lower levels of ability. Motor skill-based interventions are an ecologically valid and developmentally appropriate approach for fostering school readiness skills in early childhood.

Attachment quality assessed from children's family drawings links to child conduct problems and callous-unemotional behaviors.

OBJECTIVE: Recently, there has been considerable research on the origins of childhood conduct problems (CP) and callous-unemotional (CU) behaviors. This study examined associations between children's attachment representations and CP and CU behaviors during middle childhood. METHOD: At 1st grade, 1,292 children (57% European American, 42.5% African American, 0.5% other race; 50.9% girls) completed a drawing of their family, which was coded by trained raters to assess attachment representations. Primary caregivers reported on children's CP and CU behaviors. RESULTS: Children with disorganized representations showed more CP and CU behaviors than children with secure and resistant representations. They were also more likely than those with secure representations to show elevated CP without CU behaviors, CU behaviors only, and co-occurring CP and CU behaviors. CONCLUSION: These findings provide support for attachment disorganization as a correlate of CP and CU behaviors and suggest that attachment representations are likely important proximal influences on children's behavior.

Early childhood risk exposures and inflammation in early adolescence.

There is now reliable evidence that early psychosocial stress exposures are associated with behavioral health in children; the degree to which these same kinds of stress exposures predict physical health outcomes is not yet clear. We investigated the links between economic adversity, family and caregiving stress in early childhood and several markers of immune function in early adolescence. The sample is derived from the Family Life Project, a prospective longitudinal study of at-risk families. Socio-demographic and psychosocial risks have been assessed at regular intervals since the children were first assessed at 2 months of age. When the children were early adolescents, we conducted an in-depth health assessment of a subsample of families; blood samples were collected from venipuncture for interleukin(IL)-6, Tumor Necrosis Factor (TNF)-alpha, and C-reactive protein (CRP), as well as glucocorticoid resistance. Results indicated limited but reliable evidence of an association between early risk exposure and inflammation in adolescence. Specifically, caregiver depressive symptoms in early childhood predicted elevated CRP almost a decade later, and the prediction was significant after accounting for multiple covariates such as socio-economic adversity, health behaviors and body mass index. Our findings provide strong but limited evidence that early stress exposures may be associated with inflammation, suggesting one mechanism linking early stress exposure to compromised behavioral and somatic health.

Association between environmental tobacco smoke exposure across the first four years of life and manifestation of externalizing behavior problems in school-aged children.

BACKGROUND: Extensive literature in human and animal models has documented an association between maternal smoking during pregnancy and externalizing behavior in offspring. It remains unclear; however, the extent to which postnatal environmental smoke exposure is associated with behavioral development, particularly for children whose mothers did not smoke during pregnancy. The present study examined whether magnitude of exposure to environmental smoke across the first four years of life demonstrated a linear association with later externalizing symptoms. METHODS: Exposure was quantified through salivary cotinine measured when children were 6, 15, 24, and 48 months of age, providing a more accurate quantification of realized exposure than can be estimated from parental report of cigarettes smoked. Data were available for n = 1,096 (50% male; 44% African American) children recruited for the Family Life Project, a study of child development in areas of rural poverty. RESULTS: Analyses indicate a linear association between cotinine and children's symptoms of hyperactivity and conduct problems. This association remained significant after controlling for family poverty level, parental education, parental history of ADHD, hostility, depression, caregiver IQ, and obstetric complications. Furthermore, this association was unchanged when excluding mothers who smoked during pregnancy from the model. CONCLUSIONS: Findings are consistent with animal models demonstrating an effect of environmental exposure to nicotine on ongoing brain development in regions related to hyperactivity and impulsivity, and highlight the importance of mitigating children's exposure to environmental smoke, including sources that extend beyond the parents.

The development of executive function in early childhood is inversely related to change in body mass index: Evidence for an energetic tradeoff?

A well-established literature demonstrates executive function (EF) deficits in obese children and adults relative to healthy weight comparisons. EF deficits in obesity are associated with overeating and impulsive consumption of high calorie foods leading to excess weight gain and to problems with metabolic regulation and low-grade inflammation that detrimentally affect the structure and function of prefrontal cortex. Here, we test a complementary explanation for the relation between EF and body mass index (BMI) grounded in the energy demand of the developing brain. Recent work shows that the brain accounts for a lifetime peak of 66% of resting metabolic rate in childhood and that developmental changes in brain energetics and normative changes in body weight gain are closely inversely related. This finding suggests a trade-off in early childhood between energy used to support brain development versus energy used to support physical growth and fat deposition. To test this theorized energetic trade-off, we analyzed data from a large longitudinal sample (N = 1,292) and found that change in EF from age 3 to 5 years, as a proxy for brain development in energetically costly prefrontal cortex, is inversely related to change in BMI from age 2 to 5 years. Greater linear decline in BMI predicted greater linear increase in EF. We interpret this finding as tentative support for a brain-body energetic trade-off in early childhood with implications for lifetime obesity risk.

Prenatal Risk Predicts Preschooler Executive Function: A Cascade Model.

Little research has considered whether prenatal experience contributes to executive function (EF) development above and beyond postnatal experience. This study tests direct, mediated, and moderated associations between prenatal risk factors and preschool EF and IQ in a longitudinal sample of 1,292 children from the Family Life Project. A composite of prenatal risk factors (i.e., low birth weight, prematurity, maternal emotional problems, maternal prepregnancy obesity, and obstetric complications) significantly predicted EF and IQ at age 3, above quality of the postnatal environment. This relationship was indirect, mediated through infant general cognitive abilities. Quality of the postnatal home and child-care environments did not moderate the cascade model. These findings highlight the role of prenatal experience as a contributor to individual differences in cognitive development.

Early life predictors of attention deficit/hyperactivity disorder symptomatology profiles from early through middle childhood.

This study used repeated measures data to identify developmental profiles of elevated risk for ADHD (i.e., six or more inattentive and/or hyperactive-impulsive symptoms), with an interest in the age at which ADHD risk first emerged. Risk factors that were measured across the first 3 years of life were used to predict profile membership. Participants included 1,173 children who were drawn from the Family Life Project, an ongoing longitudinal study of children's development in low-income, nonmetropolitan communities. Four heuristic profiles of ADHD risk were identified. Approximately two thirds of children never exhibited elevated risk for ADHD. The remaining children were characterized by early childhood onset and persistent risk (5%), early childhood limited risk (10%), and middle childhood onset risk (19%). Pregnancy and delivery complications and harsh-intrusive caregiving behaviors operated as general risk for all ADHD profiles. Parental history of ADHD was uniquely predictive of early onset and persistent ADHD risk, and low primary caregiver education was uniquely predictive of early childhood limited ADHD risk. Results are discussed with respect to how changes to the age of onset criterion for ADHD in DSM5 may affect etiological research and the need for developmental models of ADHD that inform ADHD symptom persistence and desistance.

Effects of Behavioral Treatment Modified to Fit Children with Conduct Problems and Callous-Unemotional (CU) Traits.

Research suggests that children with conduct problems (CP) and callous-unemotional (CU) traits show a diminished response to behavior therapy, perhaps due to a reward-oriented, punishment insensitive learning style. Children with CP and CU may benefit from personalizing behavioral treatment for them by emphasizing rewards and de-emphasizing punishments. This hypothesis was tested in a sample of 46 children (78.3% boys), ages 7.0 to 12.6 years (M = 9.3, SD = 1.4). All participants met criteria for ODD and ADHD and 63% also met criteria for CD. Participants were oversampled for high CU, but CU scores ranged from average to high. Children received four weeks of modified behavior therapy that emphasized rewards and de-emphasized punishments and four weeks of treatment as usual, which was standard behavior therapy that balanced rewards and punishments. Treatments were implemented in a summer treatment program and compared using a within-subjects design, with order of treatment counterbalanced. Disruptive behavior was equal or slightly higher in modified behavior therapy than in standard behavior therapy on point system measures, but lower on parent weekly ratings. End of treatment ratings showed both treatments produced significant improvements compared to pre-treatment ratings but did not differ from each other. Personalizing behavior therapy for children with CP and CU produced inconsistent findings relative to standard behavior therapy. Behavior therapy is likely to be a necessary part of treatment for children with CP and CU, but treatment personalization efforts may provide some benefit by addressing other deficits shown by these children.

Measuring executive function skills in young children in Kenya: Associations with school readiness.

Most of what is known about the association between children's executive function (EF) and school readiness skills is derived from research conducted in Western countries. We tested whether these associations were evident in a middle-income country context. Participants were 1,480 children, aged 4-7 years old, who participated in an endline assessment of the Tayari program, an early childhood education (ECE) model that is being delivered by the Kenyan education system. High rates of task completion, low rates of floor effects, and high rates of assessor quality ratings supported the feasibility of large-scale direct assessments of EF with young children. Assessor ratings of children's attention-related behaviors during testing were positively associated with their performance on EF tasks (rs = 0.12-0.27). An EF composite score was not related to demographic factors or to children's exposure to the Tayari program. However, the EF composite score was uniquely associated with performance-based measures of early literacy (ß = 0.18, 95% confidence interval [CI] = 0.05, 0.31), early numeracy (ß = 0.16, 95% CI = 0.07, 26), and social-emotional competencies (ß = 0.12, 95% CI = 0.03, 0.20), even after adjustment for multiple covariates. These results are discussed with respect to the ways in which EF skills inform ongoing efforts to invest in ECE in low- and middle-income countries.

Magnitude and Chronicity of Environmental Smoke Exposure Across Infancy and Early Childhood in a Sample of Low-Income Children.

INTRODUCTION: Infants and young children may be at an increased risk for second- and thirdhand exposure to tobacco smoke because of increased respiration rate and exposure to surface residue. However, relatively fewer studies have examined biomarkers of exposure (cotinine) in children under age 4 years. This study examines the magnitude and chronicity of exposure across early childhood among children from low-income families in order to better characterize contextual risk factors associated with exposure. METHODS: A total of 1292 families were recruited in six nonurban counties of Pennsylvania and North Carolina. Cotinine was assayed from infant saliva at 6, 15, 24, and 48 months of age (N = 1218), and categorized as low (≤0.45 ng/mL), moderate (0.46-12 ng/mL), or high (≥12 ng/mL) at each time point. Categories were highly correlated across time. Latent class analysis was used to summarize patterns of exposure categories across time. RESULTS: Magnitude of exposure in this sample was high, with approximately 12% of infants registering cotinine values at least 12 ng/mL, consistent with active smoking in adults. Greater exposure was associated with lower income, less education, more residential instability, and more instability in adult occupants in the home, whereas time spent in center-based day care was associated with lower exposure. CONCLUSIONS: Young children from low-income, nonurban communities appear to bear a higher burden of secondhand smoke exposure than previous studies have reported. Results contribute to understanding populations at greater risk, as well as specific, potentially malleable, environmental factors that may be examined as direct contributors to exposure. IMPLICATIONS: Results suggest that infants from low-income, nonurban families have higher risk for environmental smoke exposure than data from nationally representative samples. Predictors of exposure offer insights into specific factors that may be targeted for risk reduction efforts, specifically conditions of children's physical space. In addition to considering the increases in risk when an adult smoker lives in a child's home, families should also attend to the possible risk embedded within the home itself, such as residual smoke from previous occupants. For high-risk children, day care appears to mitigate the magnitude of exposure by providing extended time in a smoke-free environment.

Parenting and Cortisol in Infancy Interactively Predict Conduct Problems and Callous-Unemotional Behaviors in Childhood.

This study examines observed maternal sensitivity, harsh-intrusion, and mental-state talk in infancy as predictors of conduct problems (CP) and callous-unemotional (CU) behaviors in middle childhood, as well as the extent to which infants' resting cortisol and cortisol reactivity moderate these associations. Using data from the Family Life Project (n = 1,292), results indicate that maternal sensitivity at 6 months predicts fewer CP at first grade, but only for infants who demonstrate high levels of cortisol reactivity. Maternal harsh intrusion predicts fewer empathic-prosocial behaviors, a component of CU behaviors, but only for infants who demonstrate high resting cortisol. Findings are discussed in the context of diathesis-stress and differential susceptibility models.

The benefits of adding a brief measure of simple reaction time to the assessment of executive function skills in early childhood.

Early childhood represents a period of rapid cognitive developmental change in executive function (EF) skills along with a variety of related cognitive processes, including processing speed. This leads to interpretational challenges in that children's performance on EF tasks reflects more than EF skills per se. We tested whether the inclusion of a brief measure of simple reaction time (SRT) during EF assessments could help to partially address this challenge. Data were drawn from a cross-sectional convenience sample of 830 preschool-aged children. Individual differences in SRT were significantly associated with performance on all tasks (R2s = .09-.26); slower performance on the SRT task was associated with poorer performance on each EF task. Age-related differences in individual EF tasks were reduced by approximately one half after accounting for age-related differences in SRT, and EF task scores were less coherent (i.e., less strongly intercorrelated with each other) after the removal of SRT. Age-related differences in EF were smaller (Cohen ds = 1.36 vs. 0.78), and poverty-related differences in EF were larger (Cohen ds = 0.30 vs. 0.46) after accounting for SRT-related variation. Finally, consistent with previous studies, SRT-related differences in fluid reasoning were mediated by EF skills. Results are discussed with respect to using a brief measure of SRT to partially address the problem of measurement impurity at the level of individual EF tasks.

Automated respiratory sinus arrhythmia measurement: Demonstration using executive function assessment.

Respiratory sinus arrhythmia (RSA) is a quantitative metric that reflects autonomic nervous system regulation and provides a physiological marker of attentional engagement that supports cognitive and affective regulatory processes. RSA can be added to executive function (EF) assessments with minimal participant burden because of the commercial availability of lightweight, wearable electrocardiogram (ECG) sensors. However, the inclusion of RSA data in large data collection efforts has been hindered by the time-intensive processing of RSA. In this study we evaluated the performance of an automated RSA-scoring method in the context of an EF study in preschool-aged children. The absolute differences in RSA across both scoring methods were small (mean RSA differences = -0.02-0.10), with little to no evidence of bias for the automated relative to the hand-scoring approach. Moreover, the relative rank-ordering of RSA across both scoring methods was strong (rs = .96-.99). Reliable changes in RSA from baseline to the EF task were highly similar across both scoring methods (96%-100% absolute agreement; Kappa = .83-1.0). On the basis of these findings, the automated RSA algorithm appears to be a suitable substitute for hand-scoring in the context of EF assessment.

Maternal prepregnancy body mass index and offspring attention-deficit/hyperactivity disorder: a quasi-experimental sibling-comparison, population-based design.

BACKGROUND: High maternal prepregnancy body mass index (BMI) has been associated with increased risk of offspring attention-deficit/hyperactivity disorder (ADHD). However, whether this effect is attributable to maternal or familial level confounds has been little examined. METHODS: The present study sought to examine these associations, utilizing data from the medical records of a health care system which treats 350,000 patients annually and a sibling-comparison design in a sample of 4,682 children born to 3,645 mothers. RESULTS: When examining the overall maternal effect, a linear association was observed between maternal prepregnancy BMI and child ADHD [b = 0.04, 95% confidence interval (95% CI) = 0.02-0.06, p = .0003], such that a one-unit (i.e. 1 kg/m2 ) increase in prepregnancy BMI was associated with a 4% increase in the odds of ADHD (exp b = 1.04). However, when the model was reparameterized to take full advantage of the sibling design to allow for the examination of both maternal and child-specific effects, the child-specific prepregnancy BMI effect was not reliably different from zero (b = -0.08, 95% CI = -0.23 to 0.06, p = .24). In contrast, at the maternal-level, average prepregnancy BMI was a reliably non-zero predictor of child ADHD (b = 0.04, 95% CI = 0.02-0.06, p < .0001) with each one-unit increase in maternal prepregnancy BMI associated with a 4.2% increase in the odds of ADHD (exp b = 1.04, 95% CI = 1.02-1.06). CONCLUSIONS: The association between maternal prepregnancy BMI and offspring ADHD may be better accounted for by familial or maternal confounds rather than a direct causal effect of BMI.

On the Practical Interpretability of Cross-Lagged Panel Models: Rethinking a Developmental Workhorse.

Reciprocal feedback processes between experience and development are central to contemporary developmental theory. Autoregressive cross-lagged panel (ARCL) models represent a common analytic approach intended to test such dynamics. The authors demonstrate that-despite the ARCL model's intuitive appeal-it typically (a) fails to align with the theoretical processes that it is intended to test and (b) yields estimates that are difficult to interpret meaningfully. Specifically, using a Monte Carlo simulation and two empirical examples concerning the reciprocal relation between spanking and child aggression, it is shown that the cross-lagged estimates derived from the ARCL model reflect a weighted-and typically uninterpretable-amalgam of between- and within-person associations. The authors highlight one readily implemented respecification that better addresses these multiple levels of inference.

Observed temperament from ages 6 to 36 months predicts parent- and teacher-reported attention-deficit/hyperactivity disorder symptoms in first grade.

This study tested the prospective association between observational indicators of temperament, which were obtained across multiple assessments when children were 6-36 months of age, and parent and teacher reports of children's attention-deficit/hyperactivity disorder (ADHD) behaviors, when children were in first grade. Data were drawn from the Family Life Project and included 1,074 children for whom temperament and either parent- or teacher-reported ADHD behavioral data were available. The results of variable-centered regression models indicated that individual differences in temperament regulation, but not temperamental reactivity, was uniquely predictive of parent- and teacher-reported ADHD behaviors. Latent profile analyses were used to characterize configurations of temperamental reactivity and regulation. Person-centered regression models were subsequently estimated in which temperamental profile membership replaced continuous indicators of temperamental reactivity and regulation as predictors. The results of person-centered regression models indicated that temperamental reactivity and regulation both contributed (both alone and in combination) to the prediction of subsequent ADHD behaviors. In general, the predictive associations from early temperament to later ADHD were of modest magnitude (R 2 = .10-.17). Results are discussed with respect to interest in the early identification of children who are at elevated risk for later ADHD.

Callous-Unemotional Traits Among Adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD): Associations with Parenting.

This study examined the extent to which positive and negative parenting relates to conduct problems (CP) and callous-unemotional (CU) traits among 172 adolescents (72 % males; Mage = 16.91 years, SD = .67) with attention-deficit/hyperactivity disorder and whether CU traits moderate the link between parenting and CP. Mothers reported on their adolescents' CP, CU traits, and their own parenting practices. Maternal behaviors were observed during a problem-solving communication task. Parents who engaged in more positive parenting (self-reported and observed) reported their adolescents as having lower levels of CU traits. No effect was found for negative parenting. Moderation analyses indicated that lower levels of positive maternal behavior was only associated with higher CP in the presence of higher levels of CU traits. Negative parenting was positively related to CP regardless of CU traits. Positive parenting, irrespective of measurement approach, uniquely relates to adolescents' CU traits while both positive and negative parenting relate to CP.

Emotion Recognition Deficits among Children with Conduct Problems and Callous-Unemotional Behaviors.

Deficits in emotion recognition have been associated with psychopathic and callous-unemotional (CU) behaviors among adults, adolescents, and children. However, few previous studies have examined such associations exclusively during early and middle childhood, or demographic differences in emotion recognition that may result from early emotion socialization experiences. The current study used a large, population-stratified, randomly-selected sample of 2nd grade children living in areas of high rural poverty to examine group differences in emotion recognition among children showing no conduct problems or CU behaviors (typical), conduct problems without CU behaviors (CP-only), and both CP and CU behaviors (CP+CU). Primary caregivers reported on children's conduct problems and callous-unemotional behaviors at 1st grade and children completed a computerized facial emotion recognition task at 2nd grade. Results indicated that CP/CU group differences in emotion recognition accuracy were moderated by child race, with children in the typical group showing better overall accuracy and better recognition of fearful and happy faces among European American children, whereas no group differences were found among African American children. Implications for emotion socialization, etiology of CP and CU behaviors, and future directions for research and treatment are discussed.

The interplay among socioeconomic status, household chaos, and parenting in the prediction of child conduct problems and callous-unemotional behaviors.

Child conduct problems (CP) reflect a heterogeneous collection of oppositional, aggressive, norm-violating, and sometimes violent behaviors, whereas child callous-unemotional (CU) behaviors reflect interpersonal styles of interactions reflecting a lack of guilt and empathy as well as uncaring and shallow emotional responses to others. Taken together, high levels of child CP and CU behaviors are thought to identify a relatively homogenous group of children at elevated risk for persistent and more severe problem behaviors across childhood and into adulthood. Although a large body of research has examined the developmental etiology of CP behaviors, only recently has a developmental psychopathology approach been applied to early CU behaviors. The current study examines multiple levels of contextual influences during the first years of life, including family socioeconomic status, household chaos, and parenting behaviors, on CP and CU behaviors assessed during the first-grade year. Whereas previous studies found associations between parenting behaviors and child problem behaviors moderated by household chaos, the current study found no evidence of moderation. However, path analyses suggest that the associations between child CP and CU behaviors and the contextual variables of socioeconomic status (family income and parental education) and household chaos (disorganization and instability) were mediated by maternal sensitive and harsh-intrusive parenting behavior. Analyses are presented, interpreted, and discussed with respect to both bioecological and family stress models of development.