Postnatal Brain Trajectories and Maternal Intelligence Predict Childhood Outcomes in Complex CHD.

Objective: To determine whether early structural brain trajectories predict early childhood neurodevelopmental deficits in complex CHD patients and to assess relative cumulative risk profiles of clinical, genetic, and demographic risk factors across early development. Study Design: Term neonates with complex CHDs were recruited at Texas Children's Hospital from 2005-2011. Ninety-five participants underwent three structural MRI scans and three neurodevelopmental assessments. Brain region volumes and white matter tract fractional anisotropy and radial diffusivity were used to calculate trajectories: perioperative, postsurgical, and overall. Gross cognitive, language, and visuo-motor outcomes were assessed with the Bayley Scales of Infant and Toddler Development and with the Wechsler Preschool and Primary Scale of Intelligence and Beery-Buktenica Developmental Test of Visual-Motor Integration. Multi-variable models incorporated risk factors. Results: Reduced overall period volumetric trajectories predicted poor language outcomes: brainstem ((ß, 95% CI) 0.0977, 0.0382-0.1571; p = 0.0022) and white matter (0.0023, 0.0001-0.0046; p = 0.0397) at 5 years; brainstem (0.0711, 0.0157-0.1265; p = 0.0134) and deep grey matter (0.0085, 0.0011-0.0160; p = 0.0258) at 3 years. Maternal IQ was the strongest contributor to language variance, increasing from 37% at 1 year, 62% at 3 years, and 81% at 5 years. Genetic abnormality's contribution to variance decreased from 41% at 1 year to 25% at 3 years and was insignificant at 5 years. Conclusion: Reduced postnatal subcortical-cerebral white matter trajectories predicted poor early childhood neurodevelopmental outcomes, despite high contribution of maternal IQ. Maternal IQ was cumulative over time, exceeding the influence of known cardiac and genetic factors in complex CHD, underscoring the importance of heritable and parent-based environmental factors.

Quantitative Magnetic Resonance Cerebral Spinal Fluid Flow Properties and Executive Function Cognitive Outcomes in Congenital Heart Disease.

Cerebrospinal fluid (CSF) circulation has recently been shown to be important in nutrient distribution, waste removal, and neurogenesis. Increased CSF volumes are frequently observed in congenital heart disease (CHD) and are associated with neurodevelopmental deficits. This suggests prolonged perturbation to the CSF system and possible interference to its homeostatic function, which may contribute to the neurodevelopmental deficits in CHD. CSF flow has yet to be studied in CHD patients, but the pulsatile flow of CSF throughout the brain is driven mainly by cardiopulmonary circulation. Given the underlying heart defects in CHD, the cardiopulmonary circulatory mechanisms in CHD might be impaired with resultant perturbation on the CSF circulation. In this study, we determine whether CSF flow, using MRI measurements of static and dynamic pulsatile flow, is abnormal in youths with CHD compared to healthy controls in relation to executive cognitive function. CSF flow measurements were obtained on a total of 58 child and young adult participants (CHD=20, healthy controls = 38). The CSF flow was measured across the lumen of the Aqueduct of Sylvius using cardiac-gated phase-contrast MRI at 3.0T. Static pulsatility was characterized as anterograde and retrograde peak velocities, mean velocity, velocity variance measurements, and dynamic pulsatility calculated as each participant's CSF flow deviation from the study cohort's consensus flow measured with root mean squared deviation (RMSD) were obtained. The participants had neurocognitive assessments for executive function with focus on inhibition, cognitive flexibility, and working memory domains. The CHD group demonstrated greater dynamic pulsatility (higher overall flow RMSD over the entire CSF flow cycle) compared to controls (p=0.0353), with no difference detected in static pulsatility measures. However, lower static CSF flow pulsatility (anterograde peak velocity: p=0.0323) and lower dynamic CSF flow pulsatility (RMSD: p=0.0181) predicted poor inhibitory executive function outcome. Taken together, while the whole CHD group exhibited higher dynamic CSF flow pulsatility compared to controls, the subset of CHD subjects with relatively reduced static and dynamic CSF flow pulsatility had the worst executive functioning, specifically the inhibition domain. These findings suggest that altered CSF flow pulsatility may be central to not only brain compensatory mechanisms but can also drive cognitive impairment in CHD. Further studies are needed to investigate possible mechanistic etiologies of aberrant CSF pulsatility (i.e. primary cardiac hemodynamic disturbances, intrinsic brain vascular stiffness, altered visco-elastic properties of tissue, or glial-lymphatic disturbances), which can result in acquired small vessel brain injury (including microbleeds and white matter hyperintensities).

Complex Regulation of Protocadherin Epigenetics on Aging-Related Brain Health.

Life expectancy continues to increase in the high-income world due to advances in medical care; however, quality of life declines with increasing age due to normal aging processes. Current research suggests that various aspects of aging are genetically modulated and thus may be slowed via genetic modification. Here, we show evidence for epigenetic modulation of the aging process in the brain from over 1800 individuals as part of the Framingham Heart Study. We investigated the methylation of genes in the protocadherin (PCDH) clusters, including the alpha (PCHDA), beta (PCDHB), and gamma (PCDHG) clusters. Reduced PCDHG, elevated PCDHA, and elevated PCDHB methylation levels were associated with substantial reductions in the rate of decline of regional white matter volume as well as certain cognitive skills, independent of overall accelerated or retarded aging as estimated by a DNA clock. These results are likely due to the different effects of the expression of genes in the alpha, beta, and gamma PCHD clusters and suggest that experience-based aging processes related to a decline in regional brain volume and select cognitive skills may be slowed via targeted epigenetic modifications.

Psychometric properties of the NIH Toolbox Cognition and Emotion Batteries among children and adolescents with congenital heart defects.

The NIH Toolbox offers brief, computerized measures of cognitive and psychosocial functioning. However, its psychometric properties were established among typically developing children and adolescents. The current study provides the first comprehensive assessment of its psychometric properties among young patients with congenital heart defects (CHD). We prospectively recruited 58 patients with CHD and 80 healthy controls between the ages of 6 and 17. Participants completed the NIH Toolbox Cognition and Emotion Batteries, a battery of clinician-administered neuropsychological tests, and ratings of their quality of life. Their parents also completed ratings of their functioning. On the Cognition Battery, we found expectable group differences and developmentally expected gains across ages. For the most part, composites and subtests were significantly correlated with neuropsychological measures of similar constructs. Higher scores were generally associated with ratings of better day-to-day functioning among children with CHD. On the Emotion Battery, we found no significant group differences, echoing prior research. For the most part, scales showed acceptable internal consistency among both groups. There was adequate construct coherence for most of questionnaires among healthy control but not participants with CHD. Correlations with a comparison tool were largely within expectable directions. The NIH Toolbox may provide a valid and useful assessment of cognitive functioning among youths with CHD. While it may offer reliable and valid scales of psychosocial functioning, further research is needed to understand the meaningfulness of the scales for participants with CHD.

Academic achievement, same- and cross-ethnic positive peer regard among Asian American and Latinx adolescents.

This article presents a short-term longitudinal study examining bidirectional associations between academic achievement and positive peer regard among Asian American and Latinx adolescents. Specifically, our investigation distinguished between positive peer regard within and across different ethnic groups in a diverse school setting. Three hundred and thirty-five middle school students (52.8% girls; 65% Asian American, 35% Latinx; assessment at the first time point Mage = 12.27 years, SD = 0.71) were followed across two consecutive school years. Participants completed a peer-nomination inventory assessing multiple dimensions of positive peer regard (i.e., reciprocal friendship, social acceptance, and respect), and grades were obtained from school records. Academic achievement was predictive of prospective positive peer regard received from same-ethnic peers only for Asian American adolescents. In contrast, academic achievement predicted prospective positive peer regard received from cross-ethnic peers only for Latinx adolescents. These results suggest that academic achievement was linked to social gains with peers from different ethnic backgrounds for Asian American and Latinx students. The findings underscore the importance of disentangling the sources of positive peer regard in multiethnic school environments. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Cerebral Spinal Fluid Volumetrics and Paralimbic Predictors of Executive Dysfunction in Congenital Heart Disease: A Machine Learning Approach Informing Mechanistic Insights.

The relationship between increased cerebral spinal fluid (CSF) ventricular compartments, structural and microstructural dysmaturation, and executive function in patients with congenital heart disease (CHD) is unknown. Here, we leverage a novel machine-learning data-driven technique to delineate interrelationships between CSF ventricular volume, structural and microstructural alterations, clinical risk factors, and sub-domains of executive dysfunction in adolescent CHD patients. We trained random forest regression models to predict measures of executive function (EF) from the NIH Toolbox, the Delis-Kaplan Executive Function System (D-KEFS), and the Behavior Rating Inventory of Executive Function (BRIEF) and across three subdomains of EF - mental flexibility, working memory, and inhibition. We estimated the best parameters for the random forest algorithm via a randomized grid search of parameters using 10-fold cross-validation on the training set only. The best parameters were then used to fit the model on the full training set and validated on the test set. Algorithm performance was measured using root-mean squared-error (RMSE). As predictors, we included patient clinical variables, perioperative clinical measures, microstructural white matter (diffusion tensor imaging- DTI), and structural volumes (volumetric magnetic resonance imaging- MRI). Structural white matter was measured using along-tract diffusivity measures of 13 inter-hemispheric and cortico-association fibers. Structural volumes were measured using FreeSurfer and manual segmentation of key structures. Variable importance was measured by the average Gini-impurity of each feature across all decision trees in which that feature is present in the model, and functional ontology mapping (FOM) was used to measure the degree of overlap in feature importance for each EF subdomain and across subdomains. We found that CSF structural properties (including increased lateral ventricular volume and reduced choroid plexus volumes) in conjunction with proximate cortical projection and paralimbic-related association white matter tracts that straddle the lateral ventricles and distal paralimbic-related subcortical structures (basal ganglia, hippocampus, cerebellum) are predictive of two-specific subdomains of executive dysfunction in CHD patients: cognitive flexibility and inhibition. These findings in conjunction with combined RF models that incorporated clinical risk factors, highlighted important clinical risk factors, including the presence of microbleeds, altered vessel volume, and delayed PDA closure, suggesting that CSF-interstitial fluid clearance, vascular pulsatility, and glymphatic microfluid dynamics may be pathways that are impaired in CHD, providing mechanistic information about the relationship between CSF and executive dysfunction.

Increased Cerebello-Prefrontal Connectivity Predicts Poor Executive Function in Congenital Heart Disease.

BACKGROUND: Children and adolescents with congenital heart disease (CHD) are at risk for cognitive impairments, such as executive function deficits and motor delays, which can impact their academic and adaptive functioning as well as their quality of life. We investigated whether alterations in connectivity between the prefrontal and cerebellar brain structures exist between CHD and control cohorts and if these alterations could predict cognitive or motor impairment among youths with CHD. METHODS: 53 participants with CHD and 73 healthy control participants completed multi-modal magnetic resonance imaging (MRI) of the brain, including high-resolution diffusion tensor imaging at 3T. We measured connectivity from masked regions of interest in the cerebellum to the frontal cortex using a probabilistic tractography method. Participants also completed neuropsychological tests of cognitive and motor skills using the NIH Toolbox. RESULTS: In the CHD group, fractional anisotropy (FA) was increased in the cognitive loop connectivity pathways, including from the right cerebellum to the left thalamus (p = 0.0002) and from the left thalamus to the left medial frontal gyrus (MFG) (p = 0.0048) compared with the healthy control group. In contrast, there were no differences between CHD and controls in motor loop connectivity pathways. An increase in FA from the right thalamus to the MFG tract in the cognitive loop (posterior subdivision) predicted (p = 0.03) lower scores on the NIHTB tests, including those of executive functioning. A transient increase in connectivity of the cognitive loop in the adolescent group was observed relative to the child and adult groups. CONCLUSIONS: Our results suggest that selective alteration of cerebellum-cerebral connectivity circuitry within the cognitive loops predicts cognitive dysfunction in CHD youth. Our study suggests a critical period of cerebellar circuitry plasticity in the adolescent period in CHD subjects that drives neurocognitive function. Further replication and validation in other pediatric CHD cohorts is warranted for future work.

Core components of a rehabilitation program in pediatric cardiac disease.

There is increasing effort in both the inpatient and outpatient setting to improve care, function, and quality of life for children with congenital heart disease, and to decrease complications. As the mortality rates of surgical procedures for congenital heart disease decrease, improvement in perioperative morbidity and quality of life have become key metrics of quality of care. Quality of life and function in patients with congenital heart disease can be affected by multiple factors: the underlying heart condition, cardiac surgery, complications, and medical treatment. Some of the functional areas affected are motor abilities, exercise capacity, feeding, speech, cognition, and psychosocial adjustment. Rehabilitation interventions aim to enhance and restore functional ability and quality of life for those with physical impairments or disabilities. Interventions such as exercise training have been extensively evaluated in adults with acquired heart disease, and rehabilitation interventions for pediatric patients with congenital heart disease have similar potential to improve perioperative morbidity and quality of life. However, literature regarding the pediatric population is limited. We have gathered a multidisciplinary team of experts from major institutions to create evidence- and practice-based guidelines for pediatric cardiac rehabilitation programs in both inpatient and outpatient settings. To improve the quality of life of pediatric patients with congenital heart disease, we propose the use of individualized multidisciplinary rehabilitation programs that include: medical management; neuropsychology; nursing care; rehabilitation equipment; physical, occupational, speech, and feeding therapies; and exercise training.

Psychometric Properties of the NIH Toolbox Cognition and Emotion Batteries Among Children and Adolescents with Congenital Heart Defects.

Objective: The NIH Toolbox offers brief, computerized measures of cognitive and psychosocial functioning. However, its psychometric properties were established among typically developing children and adolescents. The current study provides the first comprehensive assessment of its psychometric properties among young patients with congenital heart defects (CHD). Study Design: We prospectively recruited 58 patients with CHD and 80 healthy controls between the ages of 6 and 17. Participants completed the NIH Toolbox Cognition and Emotion Batteries, a battery of clinician-administered neuropsychological tests, and ratings of their quality of life. Their parents also completed ratings of their functioning. Results: On the Cognition Battery, we found expectable group differences and developmentally expected gains across ages. For the most part, composites and subtests were significantly correlated with neuropsychological measures of similar constructs. Higher scores were generally associated with ratings of better day-to-day functioning among children with CHD. On the Emotion Battery, we found no significant group differences, echoing prior research. For the most part, scales showed acceptable internal consistency among both groups. There was adequate construct coherence for most of questionnaires among healthy control but not participants with CHD. Correlations with a comparison tool were largely within expectable directions. Conclusion: The NIH Toolbox may provide a valid and useful assessment of cognitive functioning among children and adolescents with CHD. While it may offer reliable and valid scales of psychosocial functioning, further research is needed to understand the meaningfulness of the scales for participants with CHD.

Impaired Neurovascular Function Underlies Poor Neurocognitive Outcomes and Is Associated with Nitric Oxide Bioavailability in Congenital Heart Disease.

We use a non-invasive MRI proxy of neurovascular function (pnvf) to assess the ability of the vasculature to supply baseline metabolic demand, to compare pediatric and young adult congenital heart disease (CHD) patients to normal referents and relate the proxy to neurocognitive outcomes and nitric oxide bioavailability. In a prospective single-center study, resting-state blood-oxygen-level-dependent (BOLD) and arterial spin labeling (ASL) MRI scans were successfully obtained from 24 CHD patients (age = 15.4 ± 4.06 years) and 63 normal referents (age = 14.1 ± 3.49) years. Pnvf was computed on a voxelwise basis as the negative of the ratio of functional connectivity strength (FCS) estimated from the resting-state BOLD acquisition to regional cerebral blood flow (rCBF) as estimated from the ASL acquisition. Pnvf was used to predict end-tidal CO2 (PETCO2) levels and compared to those estimated from the BOLD data. Nitric oxide availability was obtained via nasal measurements (nNO). Pnvf was compared on a voxelwise basis between CHD patients and normal referents and correlated with nitric oxide availability and neurocognitive outcomes as assessed via the NIH Toolbox. Pnvf was shown as highly predictive of PETCO2 using theoretical modeling. Pnvf was found to be significantly reduced in CHD patients in default mode network (DMN, comprising the ventromedial prefrontal cortex and posterior cingulate/precuneus), salience network (SN, comprising the insula and dorsal anterior cingulate), and central executive network (CEN, comprising posterior parietal and dorsolateral prefrontal cortex) regions with similar findings noted in single cardiac ventricle patients. Positive correlations of Pnvf in these brain regions, as well as the hippocampus, were found with neurocognitive outcomes. Similarly, positive correlations between Pnvf and nitric oxide availability were found in frontal DMN and CEN regions, with particularly strong correlations in subcortical regions (putamen). Reduced Pnvf in CHD patients was found to be mediated by nNO. Mediation analyses further supported that reduced Pnvf in these regions underlies worse neurocognitive outcome in CHD patients and is associated with nitric oxide bioavailability. Impaired neuro-vascular function, which may be non-invasively estimated via combined arterial-spin label and BOLD MR imaging, is a nitric oxide bioavailability dependent factor implicated in adverse neurocognitive outcomes in pediatric and young adult CHD.

Cerebellar and Prefrontal Structures Associated With Executive Functioning in Pediatric Patients With Congenital Heart Defects.

Objective: Children, adolescents, and young adults with congenital heart defects (CHD) often display executive dysfunction. We consider the prefrontal and cerebellar brain structures as mechanisms for executive dysfunction among those with CHD. Methods: 55 participants with CHD (M age = 13.93) and 95 healthy controls (M age = 13.13) completed magnetic resonance imaging (MRI) of the brain, from which we extracted volumetric data on prefrontal and cerebellar regions. Participants also completed neuropsychological tests of executive functioning; their parents completed ratings of their executive functions. Results: Compared to healthy controls, those with CHD had smaller cerebellums and lateral, medial, and orbital prefrontal regions, they performed more poorly on tests of working memory, inhibitory control, and mental flexibility, and their parents rated them as having poorer executive functions across several indices. Across both groups, there were significant correlations for cerebellar and/or prefrontal volumes with cognitive assessments of working memory, mental flexibility, and inhibitory control and with parent-completed ratings of task initiation, working memory, and planning/organization. Greater prefrontal volumes were associated with better working memory, among those with larger cerebellums (with group differences based on the measure and the prefrontal region). Greater prefrontal volumes were related to better emotional regulation only among participants with CHD with smaller cerebellar volumes, and with poorer inhibition and emotional regulation only among healthy controls with larger cerebellar volumes. Conclusion: The cerebellum not only contributes to executive functioning among young individuals with CHD but may also modulate the relationships between prefrontal regions and executive functioning differently for pediatric patients with CHD vs. health controls.

Is aggression associated with biased perceptions of one's acceptance and rejection in adolescence?

In adolescence, being rejected by one's peers is positively associated with aggression. However, whether self-perceptions of being rejected or accepted by peers, and biases in these perceptions, are linked to aggression remains unclear, as the literature points to 2 perspectives: Youth are more likely to be aggressive when they (a) know or believe that they are rejected or (b) overestimate their acceptance. By addressing some of the limitations of prior studies, this study aimed to clarify how self-perceptions of status are related to concurrent and future aggression, and whether high levels of aggression are predictive of biased self-perceptions of acceptance and rejection. Data were collected in 2 consecutive school years from 572 high school students (Mage = 15.06, SD = .75; 55.4% girls). The ethnic/racial composition of the sample was 47.5% Asian, 43.1% Latino/Hispanic, 4.0% White, and 5.3% other. For well-liked youth, awareness of one's acceptance was positively associated with concurrent relational aggression, whereas for highly rejected youth, awareness of one's rejection was positively associated with concurrent overt aggression. Awareness of being rejected (i.e., high levels of both self-perceived and actual rejection) was associated with elevated levels of aggression over time. There was no evidence that youth with high levels of aggression had more biased perceptions of their status (concurrently or longitudinally) than youth with low levels of aggression. These findings help clarify how youth's status-related perceptions relate to the development of aggression. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Relationships Between Regional Cerebral Blood Flow and Neurocognitive Outcomes in Children and Adolescents With Congenital Heart Disease.

To identify regional cerebral blood flow (rCBF) alterations in children and adolescents with congenital heart disease (CHD) in relation to neurocognitive outcomes using a nonbiased data-driven approach. This is a prospective, observational study of children and adolescents with CHD without brain injury and healthy controls using pseudo-continuous arterial spin labeling (pCASL) MRI. Quantitative rCBF was compared between participants with CHD and healthy controls using a voxelwise data-driven method. Mediation analysis was then performed on a voxelwise basis, with the grouping variable as the independent variable, neurocognitive outcomes (from the NIH Toolbox Cognitive Battery) as the dependent variables, and rCBF as the mediator. After motion correction, a total of 80 studies were analyzable (27 for patients with CHD, 53 for controls). We found steeper age-related decline in rCBF among those with CHD compared to normal controls in the insula/ventromedial prefrontal regions (salience network) and the dorsal anterior cingulate and precuneus/posterior cingulate (default mode network), and posterior parietal/dorsolateral prefrontal (central executive network) (FWE-corrected P< 0.05). The reduced rCBF in the default mode/salience network was found to mediate poorer performance on an index of crystallized cognition from the NIH Toolbox Cognitive Battery in those with CHD compared to controls. In contrast, reduced rCBF in the central executive network/salience network mediated reduced deficits in fluid cognition among patients with CHD compared to controls. Regional cerebral blood flow alterations mediate domain-specific differences in cognitive performance in children and adolescents with CHD compared to healthy controls, independent of injury, and are likely related to brain and cognitive reserve mechanisms. Further research is needed to evaluate the potential of interventions in CHD targeting regional cerebral blood flow across lifespan.

The Relationship Between Dating Status and Academic and Social Functioning in Middle Adolescence.

Dating relationships are normative in middle adolescence, but the academic and social implications of different types of dating involvement remains unclear. To address this gap, this longitudinal study evaluates the association between dating status (i.e., never date, rarely date, casually date, steady relationship) and academic and social functioning in a sample of adolescents. Across two school years, 455 adolescents (53.8% female; 56.5% Asian American, 43.5% Latinx; T1 Mage = 15.04 years) reported on their dating status and peers provided nominations of popularity and aggression. Grades and standardized test scores were obtained from school records. For Asian American youth, abstaining from dating was negatively associated with subsequent popularity. Casual dating and being in a steady relationship were associated with relational and overt peer aggression over time. Gender moderated this association, such that boys in steady relationships, and girls in casual relationships were more relationally aggressive one year later. Implications are discussed in terms of problem behavior theory and adolescent intersexual competition.

Cross-Ethnic Friendships, Intergroup Attitudes, Intragroup Social Costs, and Depressive Symptoms among Asian-American and Latino-American Youth.

As American school districts become increasingly diverse, understanding the processes that promote positive intergroup relations is a critical task. The role of cross-ethnic friendships is one important factor, given the significance of these reciprocated peer relationships for social development. The current study examines the short-term longitudinal impact of cross-ethnic friendships on peer group attitudes and emotional adjustment. 524 student participants (54.8% female; Mage = 15.06 years, SD = 0.75; 47% Latino, 53% Asian-American) were followed for one year with two spring data collections. Students completed a self-report inventory assessing depressive symptoms and a peer nomination inventory assessed friendship, liking, disliking, popularity, and unpopularity. Cross-ethnic friendships were predictive of positive attitudes toward peers from other ethnic/racial groups and were also linked to declines in depressive symptoms for boys. Moreover, these positive effects did not come at a social cost, as cross-ethnic friendships were not associated with rejection by same-ethnic peers. Cross-ethnic friendships provide a unique environment that contributes to positive intergroup attitudes and beneficial socioemotional development for some youth.

Academic Functioning and Peer Influences: A Short-Term Longitudinal Study of Network-Behavior Dynamics in Middle Adolescence.

In this study, the associations between peer effects and academic functioning in middle adolescence (N = 342; 14-15 years old; 48% male) were investigated longitudinally. Similarity in achievement (grade point averages) and unexplained absences (truancy) was explained by both peer selection and peer influence, net of acceptance, and connectedness. Friendships were formed and maintained when adolescents had low levels of achievement or high levels of truancy. Friends influenced one another to increase rather than decrease in achievement and truancy. Moreover, friends' popularity moderated peer influences in truancy in reciprocal friendships but not in unilateral friendships, whereas friends' acceptance moderated peer influences in achievement in both unilateral and reciprocal friendships. The findings illustrate the dynamic interplay between peer effects and academic functioning.

A peer-nomination assessment of electronic forms of aggression and victimization.

The perpetration and receipt of electronic aggression have largely been assessed with self-report questionnaires. Using a sample of 573 adolescents, the current study compared the psychometric properties of a peer-nomination measure of electronic aggression and victimization to the more widely used self-report approach. Estimates of the reliability, stability, and concordance of peer- and self-report assessments were adequate, mirroring those from research on aggressive exchanges in school. Analyses of validity and utility revealed that peer-nominations, compared to self-reports, provide overlapping and distinct information on adolescents' social, emotional, and academic adjustment. Overall, these findings provide evidence that peer-nominations are a reliable, valid, and useful means for measuring electronic aggression and victimization. Future work will benefit from their incorporation into multi-method assessments.

Peer similarity and influence for weight-related outcomes in adolescence: a meta-analytic review.

Weight-related problems, including obesity and disordered eating, have emerged as major public health concerns for adolescents. To address these deviations from healthy eating and weight regulation, prevention and intervention efforts have targeted the influence of peers. Yet, evidence that peers influence weight-related outcomes, often inferred from similarity among peers, is inconsistent. This meta-analytic review evaluated peer similarity and influence not only for body size and symptoms of disordered eating, but also for key determinants of obesity (food intake and physical activity levels) and eating pathology (body dissatisfaction and weight control strategies). For each of the six outcomes, data was summarized from 9 to 24 independent studies. Results revealed significant, non-trivial similarity among peers across outcome variables, with the exception of disordered eating. Findings indicated that resemblances among peers were unlikely to be solely the reflection of cognitive biases or the selection of alike friends, but may be partially due to influence. To better understand the influence of peers, further longitudinal research is needed, particularly focusing on the factors that moderate susceptibility to conformity.

Longitudinal associations of electronic aggression and victimization with social standing during adolescence.

Prior empirical work has documented that the dynamics of social standing can play a critical role in the perpetration and receipt of aggression during adolescence. Recently, investigators have emphasized the emergence of new, electronic modalities for aggressive acts. Our longitudinal project therefore considered electronic forms of aggression and victimization as correlates of social standing. We recruited 415 ninth grade students (53% female) from a high school in Southern California. In the spring of two consecutive school years, participants completed peer nominations assessing their social standing, aggression, and victimization. More popular youths were concurrently more electronically aggressive and victimized than their peers. Popularity also was associated with increases in electronic aggression over time. In turn, electronic aggression was related to increases in popularity for girls and decreases for boys. We additionally found concurrent, positive associations between social acceptance and electronic forms of aggression and victimization, although these effects held only at the first time point. Among adolescent males, social acceptance also was related to increases in electronic victimization over time. Overall, our results suggest that adolescents may rely on electronic aggression to establish and maintain a privileged position in their peer hierarchy. Our results additionally highlight that popular and accepted youths, who likely possess a large, digitally-connected social network, may be at increased risk for electronic victimization.

How do you learn to walk? Thousands of steps and dozens of falls per day.

A century of research on the development of walking has examined periodic gait over a straight, uniform path. The current study provides the first corpus of natural infant locomotion derived from spontaneous activity during free play. Locomotor experience was immense: Twelve- to 19-month-olds averaged 2,368 steps and 17 falls per hour. Novice walkers traveled farther faster than expert crawlers, but had comparable fall rates, which suggests that increased efficiency without increased cost motivates expert crawlers to transition to walking. After walking onset, natural locomotion improved dramatically: Infants took more steps, traveled farther distances, and fell less. Walking was distributed in short bouts with variable paths--frequently too short or irregular to qualify as periodic gait. Nonetheless, measures of periodic gait and of natural locomotion were correlated, which indicates that better walkers spontaneously walk more and fall less. Immense amounts of time-distributed, variable practice constitute the natural practice regimen for learning to walk.