Associations of a metal mixture with iron status in U.S. adolescents: Evidence from the National Health and Nutrition Examination Survey.

Iron is needed for normal development in adolescence. Exposure to individual environmental metals (e.g., lead) has been associated with altered iron status in adolescence, but little is known about the cumulative associations of multiple metals with Fe status. We used data from the 2017-2018 National Health and Nutrition Examination Survey (NHANES) to examine associations between a metal mixture (lead, manganese, cadmium, selenium) and iron status in 588 U.S. adolescents (12-17 years). We estimated cumulative and interactive associations of the metal mixture with five iron status metrics using Bayesian Kernel Machine Regression (BKMR). Higher concentrations of manganese and cadmium were associated with lower log-transformed ferritin concentrations. Interactions were observed between manganese, cadmium, and lead for ferritin and the transferrin receptor, where iron status tended to be worse at higher concentrations of all metals. These results may reflect competition between environmental metals and iron for cellular uptake. Mixed metal exposures may alter normal iron function, which has implications for adolescent development.

Strategies and interventions for healthy adolescent growth, nutrition, and development.

Adolescence is a pivotal point in the life course, characterised by transformative physical, cognitive, and emotional growth, an openness to change, and a drive to reshape the social environment. It offers unique opportunities to adopt changes in diet and physical activity that can persist into later life. Yet pre-existing nutritional problems, including micronutrient deficiencies, food insecurity, and poor-quality diets, persist at the same time as adolescents face the rapid emergence of an obesity epidemic. Adolescent growth and nutrition has been largely overlooked in intervention and policy research. Most intervention studies have emphasised micronutrient supplementation, with few taking into account the multiple drivers of adolescent diets. This Series paper highlights that effective interventions and policies will need to cut across sectors; be supported by multifaceted and multilevel policy; and extend across education, health, food systems, social protection, and digital media. Better data standardisation and systems will be essential in coordinating and monitoring these responses. In a context of shifts in planetary ecosystems and commercial drivers, resilient food systems will need to both ensure access to healthy and affordable foods and provide the infrastructure and incentives for continuing physical activity. Intergenerational partnerships with young people will be essential in bringing about transformative change and ensuring that food policies reflect their needs and aspirations.

Gestational Age, Birth Weight, and Neurocognitive Development in Adolescents in Tanzania.

OBJECTIVES: To investigate the association between gestational age, birthweight, and birthweight adjusted for gestational age, with domains of neurocognitive development and behavioral problems in adolescents in Tanzania. STUDY DESIGN: Data from a long-term follow-up of adolescents aged 11-15 years born to women previously enrolled in a randomized controlled trial of prenatal multiple micronutrient supplementation in Dar es Salaam, Tanzania, were used. A battery of neurodevelopmental tests were administered to measure adolescent general intelligence, executive function, and behavioral problems. The INTERGROWTH-21st newborn anthropometric standards were used to derive birthweight for gestational age z-scores. We assessed the shape of relationships using restricted cubic splines and estimated the associations of gestational age, birthweight, and birthweight for gestational age z-score with adolescent development using multivariable linear regressions. RESULTS: Among adolescents studied (n = 421), higher gestational age (per week), birthweight (per 100 grams), and birthweight for gestational age z-score (per SD) were linearly associated with higher intelligence score (adjusted standardized mean difference, 0.05 SD [95% CI, 0.01-0.09], 0.04 SD [95% CI, 0.02-0.06], and 0.09 SD [95% CI, 0.01-0.17], respectively). Birthweight and birthweight for gestational age z-score, but not gestational age, were also associated with improved executive function. Low birthweight (<2500 g) was associated with lower intelligence and executive function scores. Associations between birthweight and executive function were stronger among adolescents born to women with higher education. CONCLUSIONS: The duration of gestation and birthweight were positively associated with adolescent neurodevelopment in Tanzania. These findings suggest that interventions to improve birth outcomes may also benefit adolescent cognitive function.

Functional topography of the thalamo-cortical system during development and its relation to cognition.

The thalamus has complex connections with the cortex and is involved in various cognitive processes. However, little is known about the age-related changes of thalamo-cortical connections and their relation to cognitive abilities. The present study analyzed resting-state functional connectivity between the thalamus and nine cortical functional networks (default mode network (DMN), posterior DMN, left/right executive, dorsal attention, salience, motor, visual and auditory network) in a healthy human sample (N = 95, aged 5-25 years). Cognitive abilities, including processing speed, selective attention, and cognitive flexibility were assessed using neuropsychological tests. All nine cortical resting-state networks showed functional connections to the thalamus at rest, with no effect for sex (p > 0.05). For the motor, visual, auditory, DMN, posterior DMN, salience and dorsal attention network, we found mainly bilateral thalamic projections in the mediodorsal nucleus, pulvinar and in nuclei of the lateral group. For the right and left lateralized executive network, corresponding lateralized thalamic projections were found. Thalamo-cortical connectivity strength showed significant age-related changes from distinct sub-nuclei of the thalamus to different cortical networks including the visual, DMN, salience and dorsal attention network. Further, connectivity strength of thalamo-cortical networks was associated with cognitive abilities, including processing speed, selective attention and cognitive flexibility. Better cognitive abilities were associated with increased thalamo-cortical connectivity in the pulvinar, mediodorsal nucleus, intralaminar nucleus, and nuclei from the lateral group. Alterations in the integrity of the thalamo-cortical system seem to be crucial for the development of cognitive abilities during brain maturation.

Training the anxious brain: using fMRI-based neurofeedback to change brain activity in adolescence.

Anxiety disorders are a leading cause of morbidity and entail a lot of costs. Adolescence is characterized by social fears and poor emotion regulation abilities which together increase the likelihood of the emergence of anxiety disorders. This emotion dysregulation is potentially caused by the emotion regulating brain areas, such as the prefrontal cortex and temporal cortex, that are still undergoing developmental changes throughout late adolescence. Recently, new approaches have used functional magnetic resonance imaging-based neurofeedback to help participants gain control over emotion regulation brain networks by receiving real-time feedback on their brain activity and to use effective emotion regulation abilities. In this review, we provide an overview of the developmental changes in the brain and the corresponding behavioural changes, and explore how these can be influenced during adolescence using neurofeedback. We conclude that recent studies show promising results that children and adolescents can self-regulate emotion regulation brain networks thereby supporting the development of effective emotion regulation abilities. WHAT THIS PAPER ADDS: Functional magnetic resonance imaging-based neurofeedback can be used for brain self-regulation in development. The emotion regulation networks play a key role in treating social anxiety with neurofeedback.

Bone accrual over 18 months of participation in different loading sports during adolescence.

This study investigated the impact and non-impact sports on bone mineral density accrual in adolescents over 18 months. The impact sports were beneficial for bone health (accrual of bone density). In contrast, swimmers had similar or lower bone mineral density compared with the control group depending on the skeletal site. PURPOSE: To investigate the impact and non-impact sports on bone mineral density (BMD) accrual in adolescents over a period of 18 months METHODS: The sample was composed of 71 adolescents, avarage age of 12.7 (± 1.7) years old at baseline. Bone outcomes were compared according to the loading of the sports practiced (impact sports, n = 33 [basketball, karate, and judo], non-impact sport, n = 18 [swimming], and control group, n = 20). Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry (DXA) and bone mineral apparent density (BMAD) estimated through equation. The results were compared between the groups using analysis of variance and analysis of covariance. RESULTS: Adjusted aBMD at lower limbs, whole body less head (WBLH), and adjusted WBLH BMAD were significantly greater in the impact sport group than the non-impact sport group at all time points. Adjusted upper limbs aBMD was significantly higher at the impact sports group compared to the non-impact sport group at 9 months and 18 months, besides compared to the control group at baseline and 18 months. Non-impact sport group presented a significant lower adjusted aBMD compared with control group at lower limbs and WBLH at 9 months, and at 9 months and 18 months in WBLH BMAD. There was a significant interaction (time × sport group) at upper limbs (p = 0.042) and WBLH aBMD (p = 0.006), and WBLH BMAD (p < 0.001). CONCLUSION: Impact sports were more beneficial on accumulating aBMD and BMAD over a period of 18 months, while non-impact group (swimmers) had similar and lower aBMD and BMAD compared with the control group.

Capital Femoral Epiphyseal Cupping and Extension May Be Protective in Slipped Capital Femoral Epiphysis: A Dual-center Matching Cohort Study.

BACKGROUND: Peripheral cupping of the capital femoral epiphysis over the metaphysis has been reported as a precursor of cam morphology, but may also confer stability of the epiphysis protecting it from slipped capital femoral epiphysis (SCFE). The purpose of this study was to investigate the relationship between a novel morphologic parameter of inherent physeal stability, epiphyseal cupping, and the development of SCFE in a dual-center matched-control cohort study. METHODS: We performed a dual-center age-matched and sex-matched cohort study comparing 279 subjects with unilateral SCFE and 279 radiographically normal controls from 2 tertiary children's hospitals. All SCFE patients had at least 18 months of radiographic follow-up for contralateral slip surveillance. Anteroposterior and frog lateral pelvis radiographs were utilized to measure the epiphyseal cupping ratio and the current standard measure of inherent physeal stability, the epiphyseal extension ratio. RESULTS: Control hips were found to have greater epiphyseal cupping than the contralateral uninvolved hip of SCFE subjects both superiorly (0.28±0.08 vs. 0.24±0.06; P<0.001) and anteriorly (0.22±0.07 vs. 0.19±0.06; P<0.001). The 58/279 (21%) subjects who went on to develop contralateral slip had decreased epiphyseal cupping superiorly (0.25±0.07 vs. 0.23±0.05; P=0.03) and anteriorly (0.20±0.06 vs. 0.17±0.04; P<0.001). When we compared controls with hips that did not progress to contralateral slip and hips that further developed a contralateral SCFE, 1-way ANOVA demonstrated a stepwise decrease in epiphyseal cupping and epiphyseal extension ratio in the anterior and superior planes from control hips to contralateral hips without subsequent slip to contralateral hips that developed a SCFE (P<0.01 for each). CONCLUSIONS: This study provides further evidence that epiphyseal cupping around the metaphysis is associated with decreased likelihood of SCFE and may reflect increased inherent physeal stability. Epiphyseal cupping may represent an adaptive mechanism to stabilize the epiphysis during adolescence at the long-term cost of the eventual development of associated cam-femoroacetabular impingement deformity. LEVELS OF EVIDENCE: Level III-prognostic Study.

Subcortical structural variations associated with low socioeconomic status in adolescents.

Low socioeconomic status (SES) is associated with a higher probability of multiple exposures (e.g., neighborhood violence, poor nutrition, housing instability, air pollution, and insensitive caregiving) known to affect structural development of subcortical brain regions that subserve threat and reward processing, however, few studies have examined the relationship between SES and such subcortical structures in adolescents. We examined SES variations in volume and surface morphometry of subcortical regions. The sample comprised 256 youth in eighth grade (mean age = 13.9 years), in whom high dimensional deformation mapping of structural 3T magnetic resonance imaging scans was performed. Vertex-wise linear regression analyses examined associations between income to poverty ratio and surfaces of the hippocampus, amygdala, thalamus, caudate, putamen, nucleus accumbens and pallidum, with the covariates age, pubertal status, and intracranial volume. Given sex differences in pubertal development and subcortical maturation at this age, the analyses were stratified by sex. Among males, who at this age average an earlier pubertal stage than females, the relationship between SES and local shape variation in subcortical regions was almost entirely positive. For females, the relationship between SES and local shape variation was negative. Racial identity was associated with SES in our sample, however supplementary analyses indicated that most of the associations between SES and subcortical structure were independent of it. Although these cross-sectional results are not definitive, they are consistent with a scenario where low SES delays structural maturation of subcortical regions involved with threat and reward processing. Future longitudinal studies are needed to test this hypothesis.

Effect of antenatal and infant micronutrient supplementation on middle childhood and early adolescent development outcomes in Tanzania.

BACKGROUND: There is growing evidence that nutritional interventions in the first 1000 days of life may influence long-term health and development outcomes. Few studies have examined the effect of maternal and infant micronutrient supplementation on development outcomes in sub-Saharan Africa. METHODS: We conducted a follow-up study of two randomized trials of antenatal and infant micronutrient supplementation conducted in Dar es Salaam, Tanzania. We assessed the effect of maternal multiple micronutrient (MMN) supplementation in pregnancy on development of children at 11-14 years of age. We also examined the effect of infant zinc and MMN supplementation on development at 6-8 years of age. We used generalized linear models to assess standardized mean differences (SMDs) in general intelligence, executive function, and mental health scores. RESULTS: We followed up 446 children whose mothers were enrolled in the maternal MMN supplementation trial and 365 children who were enrolled in the infant zinc and MMN supplementation trial. We found no effect of maternal MMN supplementation on general intelligence (SMD: -0.03; 95% CI: -0.15, 0.09), executive function (SMD: 0.00; 95% CI: -0.11, 0.11), and mental health scores (SMD: 0.06; 95% CI: 10.10, 0.22). We also found no effect of either infant zinc or MMN supplementation on any of the three development domains (p-values > 0.05). CONCLUSIONS: We found that antenatal MMN supplementation and infant zinc and MMN supplementation did not have a large effect on development outcomes in middle childhood and early adolescence in Tanzania.

Impact of physical growth, body adiposity and lifestyle on muscular strength and cardiorespiratory fitness of adolescents.

OBJECTIVE: To investigate the impact of physical growth, body adiposity and lifestyle on cardiorespiratory fitness and muscle strength of pubescent and post-pubescent adolescents. METHODS: Cross-sectional study with 1132 adolescents (14-19 years) in Brazil. Aerobic fitness was measured using the modified Canadian Aerobic Fitness Test. Muscle strength was assessed using manual dynamometer. Maturational stages were defined through the Tanner criteria. RESULTS: Boys at pubertal maturation stage showed higher VO2max values than those at the post-pubertal stage when the influence of body adiposity and lifestyle was disregarded. Girls at pubertal maturation stage showed higher VO2max values than those in the post-pubertal stage when the influence of age was disregarded. For muscle strength, no significant differences were found. CONCLUSIONS: The variables that influence the association between VO2max and maturational stage are different for boys and girls.

Adolescent development of insula-dependent interoceptive regulation.

Adolescence is hypothesized to be a critical period for the maturation of self-regulatory capacities, including those that depend on interoceptive sensitivity, but the neural basis of interoceptive regulation in adolescence is unknown. We used functional magnetic resonance imaging and psychophysiology to study interoceptive regulation in healthy adolescent females. Participants regulated their gut activities in response to a virtual roller coaster by deep breathing aided by visually monitoring their online electrogastrogram (EGG) activity through a virtual thermometer (i.e. gut biofeedback), or without biofeedback. Analyses focused on the insula, given its putative role in interoception. The bilateral posterior insula showed increased activation in the no-biofeedback compared to biofeedback condition, suggesting that the participants relied more on interoceptive input when exteroceptive feedback was unavailable. The bilateral dorsal anterior insula showed activation linearly associated with age during both induction and regulation, and its activation during regulation correlated positively with change of EGG in the tachygastria frequency band from induction to regulation. Induction-related activation in the bilateral ventral anterior insula was nonlinearly associated with age and peaked at mid-adolescence. These results implicate different developmental trajectories of distinct sub-regions of the insula in interoceptive processes, with implications for competing neurobiological theories of female adolescent development.

Practice of martial arts and bone mineral density in adolescents of both sexes / Prática de artes marciais e densidade mineral óssea em adolescentes de ambos os sexos

Objective: The purpose of this study was to analyze the relationship between martial arts practice (judo, karate and kung-fu) and bone mineral density in adolescents. Methods: The study was composed of 138 (48 martial arts practitioners and 90 non-practitioners) adolescents of both sexes, with an average age of 12.6 years. Bone mineral density was measured using Dual-Energy X-ray Absorptiometry in arms, legs, spine, trunk, pelvis and total. Weekly training load and previous time of engagement in the sport modality were reported by the coach. Partial correlation tested the association between weekly training load and bone mineral density, controlled by sex, chronological age, previous practice and somatic maturation. Analysis of covariance was used to compare bone mineral density values according to control and martial arts groups, controlled by sex, chronological age, previous practice and somatic maturation. Significant relationships between bone mineral density and muscle mass were inserted into a multivariate model and the slopes of the models were compared using the Student t test (control versus martial art). Results: Adolescents engaged in judo practice presented higher values of bone mineral density than the control individuals (p-value=0.042; Medium Effect size [Eta-squared=0.063]), while the relationship between quantity of weekly training and bone mineral density was significant among adolescents engaged in judo (arms [r=0.308] and legs [r=0.223]) and kung-fu (arms [r=0.248] and spine [r=0.228]). Conclusions: Different modalities of martial arts are related to higher bone mineral density in different body regions among adolescents.

Objetivo: Analisar a relação entre a prática de artes marciais (judô, karatê e kung-fu) e a densidade mineral óssea em adolescentes. Métodos: O estudo foi composto por 138 adolescentes (48 praticantes de artes marciais e 90 não praticantes) de ambos os sexos, com média de 12,6 anos. A densidade mineral óssea foi medida com absortometria radiológica de dupla energia em braços, pernas, coluna, tronco, pelve e total. A carga de treinamento semanal e o tempo anterior de envolvimento na modalidade esportiva foram relatados pelo treinador. A correlação parcial testou a associação entre a carga semanal de treinamento e a densidade mineral óssea, controlada para sexo, idade cronológica, prática anterior e maturação somática. A análise de covariância foi usada para comparar os valores de densidade mineral óssea de acordo com os grupos controle e de artes marciais, controlados para sexo, idade cronológica, prática anterior e maturação somática. Associações significativas entre a densidade mineral óssea e a massa muscular foram inseridas em um modelo multivariado e as inclinações dos modelos foram comparadas com o teste t de Student (controle versus arte marcial). Resultados: Os adolescentes envolvidos na prática de judô apresentaram valores maiores de densidade mineral óssea do que os do grupo controle (p=0,042; tamanho de efeito médio [eta-quadrado=0,063]), enquanto a relação entre a quantidade de treinos semanais e a densidade mineral óssea foi significativa entre os adolescentes praticantes de judô (braços [r=0,308] e pernas [r=0,223]) e kung-fu (braços [r=0,248] e coluna [r=0,228]). Conclusões: Diferentes modalidades de artes marciais estão relacionadas com maior densidade mineral óssea em diferentes regiões do corpo em adolescentes.

Transcending as a driver of development.

This paper draws from three different bodies of research to discuss the hypothesis that age-appropriate experiences enhance brain and cognitive development throughout the life span. These age-appropriate experiences could be considered as the drivers of development at each age, including drivers to foster development beyond adult abstract thinking, as described in Piaget's formal operational stage. We explore how a nurturing caregiver is the driver in the first 2 years of life, how language learning is the driver from 3 to 10 years, and how problem solving is the driver in the teenage years. To develop beyond adult rational thinking, we suggest that the driver is transcending thought, which can result when practicing meditations in the automatic self-transcending category, such as Transcendental Meditation.

Dispositional mindfulness is predicted by structural development of the insula during late adolescence.

Adolescence is a critical period of development, in which the increasing social and cognitive demands of independence need to be met by enhanced self-regulatory abilities. The cultivation of mindfulness has been associated with improved self-regulation in adult populations, and it is theorized that one neurodevelopmental mechanism that supports this capacity is the development of the prefrontal cortex. The current study examined the neurodevelopmental mechanisms associated with dispositional mindfulness in adolescence. Using a longitudinal within-persons design, 82 participants underwent structural magnetic resonance imaging (MRI) assessments at approximately ages 16 and 19, and also completed self-reported measurements of mindfulness at age 19. It was hypothesized that adolescents who demonstrated greater thinning of frontal cortical regions between the age of 16 and 19 would exhibit higher dispositional mindfulness levels at age 19. Results indicated that, contrary to predictions, adolescents with higher levels of mindfulness demonstrated less thinning in the left anterior insula. By contrast, higher IQ was associated with greater thinning of the right caudal middle frontal and right superior frontal regions. The involvement of insula development in mindfulness is consistent with a direct role for this structure in managing self-regulation, and in doing so concords with recent models of self-referential interoceptive awareness.

Kung-fu versus swimming training and the effects on balance abilities in young adolescents.

OBJECTIVE: Our purpose is to investigate the static balance control of young adolescents practicing kung-fu and swimming in order to find out which of these physical activities is the most effective in developing specific balance abilities in young adolescents. DESIGN: Comparative experimental study. SETTING: University laboratory research. PARTICIPANTS: Three groups of 11-13-year-old boys (12 practicing Kung-Fu, 12 practicing swimming and 12 controls). MAIN OUTCOME MEASURES: Center of pressure (CoP) excursions were registered in upright bipedal and unipedal stances on a stabilometric force platform in eyes open (EO) and eyes closed (EC) conditions. RESULTS: Kung-fu practitioners control their balance (P < .05) better than controls and swimmers in the unipedal posture when visual inputs are available. Kung-fu training improved (P < .05) the bipedal balance control in the EO condition. However, swimming training developed (P < .05) bipedal balance control in both EO and EC conditions. The swimmers showed a lower reliance on vision (P < .05) compared to kung-fu practitioners. CONCLUSIONS: Both of these physical activities could be recommended for young adolescents as recreational or rehabilitation programs as they develop specific balance abilities that could be important for improving and maintaining optimal health.

Mindfulness training for adolescents: A neurodevelopmental perspective on investigating modifications in attention and emotion regulation using event-related brain potentials.

Mindfulness training is increasingly being introduced in schools, yet studies examining its impact on the developing brain have been scarce. A neurodevelopmental perspective on mindfulness has been advocated as a powerful tool to enhance our understanding of underlying neurocognitive changes that have implications for developmental well-being research and the implementation of mindfulness in education. To stimulate more research in the developmental cognitive neuroscience of mindfulness, this article outlines possible indexes of mindfulness-based change in adolescence, with a focus on event-related brain potential (ERP) markers. We provide methodological recommendations for future studies and offer examples of research paradigms. We also discuss how mindfulness practice could impact on the development of prefrontal brain structures and enhance attention control and emotion regulation skills in adolescents, impacting in turn on their self-regulation and coping skills. We highlight advantages of the ERP methodology in neurodevelopmental research of mindfulness. It is proposed that research using established experimental tasks targeting ERP components such as the contingent negative variability, N200, error-related negativity and error positivity, P300, and late positive potential could elucidate developmentally salient shifts in the neural plasticity of the adolescent brain induced by mindfulness practice.

Mindfulness and compassion training in adolescence: a developmental contemplative science perspective.

Adolescence is a developmental period of risk, as well as a window of opportunity for cultivating positive development and thriving. It is characterized by simultaneous changes in the brain, body, mind, and social domains that offer a platform for building new skills and habits. This chapter discusses the role that secular forms of mindfulness and compassion training may play in fostering positive development in adolescence. The emerging discipline of "Developmental Contemplative Science" (DCS) is introduced, the theoretical and empirical basis of mindfulness in adolescence is illustrated in depth, and secular mindfulness and compassion practices for youth are portrayed. Last, this chapter offers an agenda for future research on connecting mindfulness to key developmental domains in adolescence.

Learning to BREATHE: an intervention to foster mindfulness in adolescence.

During adolescence, young people are traversing exciting and also challenging stages in their development. Mindfulness, if taught in a developmentally appropriate way, has the potential to be an asset in adolescents' lives. Developmentally appropriate approaches of mindfulness intervention during adolescence need to consider adolescents' social contexts (for example, school setting, peer group, family), their cognitive and emotional stages in development, and age-specific strength and vulnerabilities. This chapter puts mindfulness education into a developmental perspective, and presents the Learning to BREATHE program as a school-based universal intervention for adolescents. The authors describe developmental dimensions and themes of the program, and discuss common challenges of program implementation in schools. A case example of bringing the Learning to BREATHE program into the school context is provided.