Nicotine Exposure during Adolescence Leads to Changes of Synaptic Plasticity and Intrinsic Excitability of Mice Insular Pyramidal Cells at Later Life.

To find satisfactory treatment for nicotine addiction, synaptic and cellular mechanisms should be investigated comprehensively. Synaptic transmission, plasticity and intrinsic excitability in various brain regions are known to be altered by acute nicotine exposure. However, it has not been addressed whether and how nicotine exposure during adolescence alters these synaptic events and intrinsic excitability in the insular cortex in adulthood. To address this question, we performed whole-cell patch-clamp recordings to examine the effects of adolescent nicotine exposure on synaptic transmission, plasticity and intrinsic excitability in layer V pyramidal neurons (PNs) of the mice insular cortex five weeks after the treatment. We found that excitatory synaptic transmission and potentiation were enhanced in these neurons. Following adolescent nicotine exposure, insular layer V PNs displayed enhanced intrinsic excitability, which was reflected in changes in relationship between current strength and spike number, inter-spike interval, spike current threshold and refractory period. In addition, spike-timing precision evaluated by standard deviation of spike timing was decreased following nicotine exposure. Our data indicate that adolescent nicotine exposure enhances synaptic transmission, plasticity and intrinsic excitability in layer V PNs of the mice insular cortex at later life, which might contribute to severe nicotine dependence in adulthood.

Evaluation of childhood nutrition by dietary survey and stable isotope analyses of hair and breath.

OBJECTIVES: The natural abundances of carbon, nitrogen, and sulfur stable isotopes in hair, and of carbon isotopes in breath serve as quantitative biomarkers of protein and carbohydrate sources, but applicability of isotopes for evaluating children's diet has not been demonstrated. In this study, we sought to describe the stable isotope patterns observed in the hair and breath of children and to assess dietary variations in relation to age and ethnicity, hypothesizing that these would reflect dietary differences across age and ethnic groups and would correlate with intake variables derived from a Food Frequency Questionnaire. METHODS: Data were obtained from a cross-sectional study of non-Hispanic white (N = 115) and Hispanic (N = 97) children, aged 9-16 years, in Salt Lake City, Utah. Sampling included a hair sample, breath samples (AM and PM), and a youth/adolescent food questionnaire (YAQ). Hair was analyzed for carbon (δ13 C), nitrogen (δ15 N), and sulfur (δ34 S) isotopes, and breath samples for δ13 CAM/PM of respired CO2 . RESULTS: Non-Hispanic whites had lower δ13 C, δ15 N, δ13 CAM , and δ13 CPM values than Hispanics. Hair δ13 C and δ15 N values were correlated with protein sources, particularly for non-Hispanics. Breath δ13 C values were correlated with carbohydrate sources, particularly for Hispanic students. Non-Hispanic white students reported greater intake of total protein, animal protein, dairy, and grain than Hispanic students. Hispanic students reported higher intake of carbohydrates, particularly sweetened beverages. CONCLUSION: While YAQ and stable isotope data reflected strong cultural influences in diet, no significant gender-based nor age-based differences were detected. Significant covariation between YAQ and isotopes existed and demonstrate the potential of stable isotopes for characterizing children's diet.

New Approaches: Changing Lives.

Juvenile justice reform is improving the odds that at-risk youth become productive adults.

Factors related to obesity and overweight among Black adolescent girls in the United States.

In the United States, Black adolescents have the highest prevalence of pediatric obesity and overweight among girls. While Black girls are disproportionately affected, the reasons for this health disparity remain unclear. The authors conducted a systematic review to investigate the factors related to obesity and overweight among Black adolescent girls. The authors searched four databases for relevant English-language publications using all publication years through 2015. Fifty-one studies met the inclusion criteria and were used for this review. Using a configuration approach to synthesis, three categories were identified, paralleling the bioecological theory of human development: (1) individual, (2) interpersonal, and (3) community and societal factors. A description of each factor's association with obesity among Black adolescent girls is presented. From this review, the authors identified a diverse and vast set of individual, interpersonal, and community and societal factors explored for their relationship with obesity and overweight. Given the insufficient repetition and limited significant findings among most factors, the authors believe that multiple gaps in knowledge exist across all categories regarding the factors related to obesity and overweight among Black adolescent girls. To improve the quality of research in this area, suggested research directions and methodological recommendations are provided.

Ecological correlates of multiple sexual partnerships among adolescents and young adults in urban Cape Town: a cumulative risk factor approach.

Studies in South Africa have reported unsafe levels of risky sexual behvaiours among adolescents and young adults, with the country reporting the highest burden of HIV/AIDS globally, as well as a high rate of teenage pregnancy. While determinants of risky sexual behaviours have been investigated for factors occurring at the individual and household levels, not fully explored in the literature is the effect of community level factors. Furthermore, it is unclear whether risk factors occurring within the ecology of adolescents and young adults act cumulatively to influence their sexual practices. This article aims to address this knowledge gap using a case study of the Cape Area Panel Study of adolescents and young adults in urban Cape Town, South Africa. The ecological framework was adopted to guide the selection of risk factors at the individual, household, and community levels. Multivariate linear discriminant function analyses were used to select significant risk factors for multiple sexual partnerships and used to produce risk indices for the respondents. The cumulative risk approach was applied to test whether significant risk factors acted cumulatively. Findings point to the importance of ecological factors in influencing outcomes of multiple sexual partnerships among respondents and further demonstrate that ecological risk factors may act cumulatively. These findings are important for South Africa that is grappling with teenage pregnancy and disproportionate HIV epidemic among the youth.

From Caregivers to Peers: Puberty Shapes Human Face Perception.

Puberty prepares mammals to sexually reproduce during adolescence. It is also hypothesized to invoke a social metamorphosis that prepares adolescents to take on adult social roles. We provide the first evidence to support this hypothesis in humans and show that pubertal development retunes the face-processing system from a caregiver bias to a peer bias. Prior to puberty, children exhibit enhanced recognition for adult female faces. With puberty, superior recognition emerges for peer faces that match one's pubertal status. As puberty progresses, so does the peer recognition bias. Adolescents become better at recognizing faces with a pubertal status similar to their own. These findings reconceptualize the adolescent "dip" in face recognition by showing that it is a recalibration of the face-processing system away from caregivers toward peers. Thus, in addition to preparing the physical body for sexual reproduction, puberty shapes the perceptual system for processing the social world in new ways.

Perceived and Objectively-Measured Neighborhood Violence and Adolescent Psychological Distress.

Prior research examining links between neighborhood violence and mental health has not been able to establish whether it is perceived levels of neighborhood violence, or actual levels of violent crime, that matter most for adolescents' psychological well-being. In this study, we ascertained both perceived neighborhood safety and objectively-measured neighborhood-level violent crime (using a novel geospatial index of police-reported crime incidents) for 4464 adolescent respondents from the California Health Interview Survey (CHIS 2011-2014). We used propensity score-matched regression models to examine associations between these measures and CHIS adolescents' symptoms of psychological distress. We found that adolescents who perceived their neighborhood to be unsafe were two times more likely than those who perceived their neighborhood to be safe to report serious psychological distress (OR = 2.4, 95 % CI = 1.20, 4.96). Adolescents who lived in areas objectively characterized by high levels of violent crime, however, were no more likely than their peers in safer areas to be distressed (OR = 1.41; 95 % CI = 0.60, 3.32). Our results suggest that, at the population level, adolescents' perceptions of neighborhood violence, rather than objective levels of neighborhood crime, are most salient for their mental health.

Volume of hippocampal subfields and episodic memory in childhood and adolescence.

Episodic memory critically depends on the hippocampus to bind the features of an experience into memory. Episodic memory develops in childhood and adolescence, and hippocampal changes during this period may contribute to this development. Little is known, however, about how the hippocampus contributes to episodic memory development. The hippocampus is comprised of several cytoarchitectural subfields with functional significance for episodic memory. However, hippocampal subfields have not been assessed in vivo during child development, nor has their relation with episodic memory been assessed during this period. In the present study, high-resolution T2-weighted images of the hippocampus were acquired in 39 children and adolescents aged 8 to 14 years (M=11.30, SD=2.38), and hippocampal subfields were segmented using a protocol previously validated in adult populations. We first validated the method in children and adolescents and examined age-related differences in hippocampal subfields and correlations between subfield volumes and episodic memory. Significant age-related increases in the subfield volume were observed into early adolescence in the right CA3/DG and CA1. The right CA3/DG subfield volumes were positively correlated with accurate episodic memory for item-color relations, and the right CA3/DG and subiculum were negatively correlated with item false alarm rates. Subfield development appears to follow a protracted developmental trajectory, and likely plays a pivotal role in episodic memory development.

Estimating volumes of the pituitary gland from T1-weighted magnetic-resonance images: effects of age, puberty, testosterone, and estradiol.

The pituitary gland is a key structure in the hypothalamic-pituitary-gonadal (HPG) axis--it plays an important role in sexual maturation during puberty. Despite its small size, its volume can be quantified using magnetic resonance imaging (MRI). Here, we study a cohort of 962 typically developing adolescents from the Saguenay Youth Study and estimate pituitary volumes using a newly developed multi-atlas segmentation method known as the MAGeT Brain algorithm. We found that age and puberty stage (controlled for age) each predicts adjusted pituitary volumes (controlled for total brain volume) in both males and females. Controlling for the effects of age and puberty stage, total testosterone and estradiol levels also predict adjusted pituitary volumes in males and pre-menarche females, respectively. These findings demonstrate that the pituitary gland grows during adolescence, and its volume relates to circulating plasma-levels of sex steroids in both males and females.

The neuroendocrine control of the circadian system: adolescent chronotype.

Scientists, public health and school officials are paying growing attention to the mechanism underlying the delayed sleep patterns common in human adolescents. Data suggest that a propensity towards evening chronotype develops during puberty, and may be caused by developmental alterations in internal daily timekeeping. New support for this theory has emerged from recent studies which show that pubertal changes in chronotype occur in many laboratory species similar to human adolescents. Using these species as models, we find that pubertal changes in chronotype differ by sex, are internally generated, and driven by reproductive hormones. These chronotype changes are accompanied by alterations in the fundamental properties of the circadian timekeeping system, including endogenous rhythm period and sensitivity to environmental time cues. After comparing the developmental progression of chronotype in different species, we propose a theory regarding the ecological relevance of adolescent chronotype, and provide suggestions for improving the sleep of human adolescents.

Adolescence: a foundation for future health.

Adolescence is a life phase in which the opportunities for health are great and future patterns of adult health are established. Health in adolescence is the result of interactions between prenatal and early childhood development and the specific biological and social-role changes that accompany puberty, shaped by social determinants and risk and protective factors that affect the uptake of health-related behaviours. The shape of adolescence is rapidly changing-the age of onset of puberty is decreasing and the age at which mature social roles are achieved is rising. New understandings of the diverse and dynamic effects on adolescent health include insights into the effects of puberty and brain development, together with social media. A focus on adolescence is central to the success of many public health agendas, including the Millennium Development Goals aiming to reduce child and maternal mortality and HIV/AIDS, and the more recent emphases on mental health, injuries, and non-communicable diseases. Greater attention to adolescence is needed within each of these public health domains if global health targets are to be met. Strategies that place the adolescent years centre stage-rather than focusing only on specific health agendas-provide important opportunities to improve health, both in adolescence and later in life.

Tpeak -tend interval in 12-lead electrocardiogram of healthy children and adolescents tpeak -tend interval in childhood.

BACKGROUND: Tpeak (Tp) to the Tend (Te) interval is an index of transmural dispersion of repolarization. Prolongation of this interval predisposes to life-threatening ventricular arrhythmias in long QT syndrome, polymorphic catecholaminergic ventricular tachycardia, Brugada syndrome and short QT syndrome and may be an indicator of increased risk of sudden cardiac death. Very little is known about TpTe interval in children and adolescents. METHODS: In 131 healthy children (64 girls) aged from 2.3 to 18.5 years (mean 9.1 years) the RR, QT, JT and TpTe intervals were measured manually in all leads of resting electrocardiogram (ECG). The statistical analysis were performed. RESULTS: TpTe intervals vary significantly (P < 0.0001) between individual leads-the longest were in lead V3 , the shortest ones in leads III and V1 . Boys had longer TpTe intervals, with statistically significant differences in leads I, aVR and precordial V2 -V6 . Greater values were also observed in older children. TpTe dispersion varied from 6 to 80 ms (mean 38.6 ms ± 14.6 ms, median 40 ms) with no gender differences and greater values in older subjects (P = 0.003). In most leads, higher TpTe/QT and TpTe/JT ratios were seen in boys regardless of age. The TpTe intervals lengthens with lowering heart rate. CONCLUSIONS: In healthy children and adolescents, TpTe intervals vary between individual leads of ECG, with the longest in lead V3 . The TpTe interval is longer in boys and in older children and prolongs as heart rate decelerates. TpTe/QT and TpTe/JT ratios are higher in boys. TpTe interval should be measured in precordial leads.

Perioperative care of adolescents.

PURPOSE OF REVIEW: To describe adolescent development within the context of perioperative anesthetic management. RECENT FINDINGS: Most adolescent deaths are as a result of unintentional injury. Motor vehicle accidents are the most common cause, with homicide the second most common cause of intentional injury. Suicide is also a significant cause of adolescent death. The thinning of gray matter following preadolescence overtakes synaptogenesis, resulting in a more efficient, adult-like brain. Although adolescent substance use has declined over the last 30 years, cigarette smoking, alcohol and illicit drug use, sexual activity, and violent behavior remain significant concerns in perioperative care. The tremendous increase in physical working capacity and maximum oxygen consumption during adolescence commonly results in the pursuit of muscularity, substance use and abuse, dieting regimens, and muscle dysmorphia. Childhood obesity has risen by more than 50% in the last 10 years. Anorexics die at a rate of 10-20% from complications of starvation or from suicide. Up to 8% of adolescents are diagnosed with major depressive disorder. Poorly controlled perioperative pain is still common. Many adolescents have decision-making capacity and therefore assent to surgery becomes an important perioperative consideration. SUMMARY: Adolescents are a very healthy population subject to unintentional and intentional injury. Emotional and judgmental maturation is a cofactor in these injuries, better appreciated through improved understanding of developmental neurobiology. In addition, increases in muscle mass, requirements for nutrition and rest, maladaptive behavior, and health choices are important for optimal perioperative care.

Imaging brain development: the adolescent brain.

The past 15 years have seen a rapid expansion in the number of studies using neuroimaging techniques to investigate maturational changes in the human brain. In this paper, I review MRI studies on structural changes in the developing brain, and fMRI studies on functional changes in the social brain during adolescence. Both MRI and fMRI studies point to adolescence as a period of continued neural development. In the final section, I discuss a number of areas of research that are just beginning and may be the subject of developmental neuroimaging in the next twenty years. Future studies might focus on complex questions including the development of functional connectivity; how gender and puberty influence adolescent brain development; the effects of genes, environment and culture on the adolescent brain; development of the atypical adolescent brain; and implications for policy of the study of the adolescent brain.

Focus on methodology: salivary bioscience and research on adolescence: an integrated perspective.

The characterization of the salivary proteome and advances in biotechnology create an opportunity for developmental scientists to measure multi-level components of biological systems in oral fluids and identify relationships with developmental processes and behavioral and social forces. The implications for developmental science are profound because from a single oral fluid specimen, information can be obtained about a broad array of biological systems and the genetic polymorphisms related to their function. The purpose of this review is to provide a conceptual and tactical roadmap for investigators interested in integrating these measurement tools into research on adolescent health and development.

Sleep improvements on days with later school starts persist after 1 year in a flexible start system.

Early school times fundamentally clash with the late sleep of teenagers. This mismatch results in chronic sleep deprivation posing acute and long-term health risks and impairing students' learning. Despite immediate short-term benefits for sleep, the long-term effects of later starts remain unresolved. In a pre-post design over 1 year, we studied a unique flexible school start system, in which 10-12th grade students chose daily between an 8:00 or 8:50AM-start. Missed study time (8:00-8:50) was compensated for during gap periods or after classes. Based on 2 waves (6-9 weeks of sleep diary each), we found that students maintained their ~ 1-h-sleep gain on later days, longitudinally (n = 28) and cross-sectionally (n = 79). This gain was independent of chronotype and frequency of later starts but attenuated for boys after 1 year. Students showed persistently better sleep quality and reduced alarm-driven waking and reported psychological benefits (n = 93) like improved motivation, concentration, and study quality on later days. Nonetheless, students chose later starts only infrequently (median 2 days/week), precluding detectable sleep extensions in the flexible system overall. Reasons for not choosing late starts were the need to make up lost study time, preference for extra study time and transport issues. Whether flexible systems constitute an appealing alternative to fixed delays given possible circadian and psychological advantages warrants further investigation.

The shape of things to come? household dependency ratio and adolescent nutritional status in rural and urban Ethiopia.

Several related demographic trends are occurring in developing countries: youth comprise a large portion of populations, fertility rates are declining, and urban dwellers are increasing. As fertility rates decline and populations age, the decline in the ratio of young dependents to working age adults is expected to free up household resources, which can be invested in human capital, including youth nutritional wellbeing. We test this hypothesis in a sample of youth (n = 1,934) in Southwestern Ethiopia. Multiple measures of achieved growth and nutritional status are explored (weight, height, mid-upper arm circumference (MUAC), body mass index (BMI) and body mass index for age z-score (BMIZ), weight for age z-score (WAZ), and height for age z-score (HAZ)). In multivariable models controlling for the effects of income, age, gender, and youth workloads, youth living in rural settings had significantly lower weight (1.24 kg lighter), MUAC (0.67 cm lower), BMI (0.45 BMI lower), BMIZ (0.27 lower), HAZ (0.14 HAZ lower), and WAZ (0.3 WAZ lower) than urban youth (all P < 0.01). Compared with youth in the lowest dependency ratio households, results show that youth in households with the highest dependency ratios were estimated to be 1.3 kg lighter, have 0.67 cm smaller MUAC, and BMI that was 0.59 lower (all P<0.01). Similar results were found for WAZ (0.21 lower) and BMIZ (0.36 lower). Youth height and HAZ were not associated with household dependency. These results may point toward increasing levels of human capital investments in Ethiopian youth as fertility levels decline and populations urbanize.

[Factors related to subjective fatigue symptoms of adolescent girls].

OBJECTIVES: To assess changes in subjective fatigue symptoms of adolescent girls over a 15-year period and investigate factors related to these symptoms. METHODS: A total of 86 items on physical health (including subjective fatigue symptoms), dietary life, and daily living were investigated and five items on physical activity were measured for approximately 100 female first-year dietetic students at a junior college each October over the 15-year period from 1994 to 2008. A total of 1,547 students (mean age, 19.2 +/- 0.3 years) were studied. Subjects were first divided into two groups using the median subjective fatigue score as the cutoff point, and annual changes in the proportion of students in the high subjective fatigue group were investigated by simple regression analysis. In addition, relationships between the two subjective fatigue groups and each item were investigated. RESULTS: 1) The proportion of students with many subjective fatigue symptoms showed a significantly increasing trend over the 15-year period. 2) Investigation of relationships between subjective fatigue symptoms and each factor revealed significance for many items, including dietary habits, life satisfaction, amount of sleep, and desire for a positive body image. 3) In order to determine which of the items were most strongly related to subjective fatigue symptoms, multiple logistic regression analysis was performed for the 15-year period as well as three 5-year periods into which it was divided. The results showed that the dietary habits score (an indicator of dietary habits) and life satisfaction were related to subjective fatigue symptoms during all four periods. As for other items, relationships were observed for amount of sleep in three, diet and salt intake score in two, and liking for coffee/tea, juice drinks, and oily food, bedtime snack, desire for body image, self-assessment of body type, and health consciousness in one. CONCLUSION: These findings indicate that perspectives in education for promoting the health of adolescent girls must include attention to dietary habits, satisfaction with life, and correct awareness of body type.

[The second birth. Some considerations about brain development in adolescence]. / El segundo nacimiento. Algunas consideraciones acerca del desarrollo cerebral durante la adolescencia.

Adolescence is a stage of life characterized by body changes as well as cognitive and behavioral modifications. The paper summarizes some of the brain changes that occur during this period, their possibilities to be impacted by experience and the resulting potential vulnerability.

Developmental changes in the human sleep EEG during early adolescence.

STUDY OBJECTIVES: To use time-frequency analysis to characterize developmental changes in the human sleep electroencephalogram (EEG) across early adolescence. DESIGN: Sleep EEG was recorded when children were 9/10 years old and 1 to 3 years later after sleeping at home on a fixed schedule for at least one week. SETTING: A 4-bed sleep laboratory. PARTICIPANTS: Fourteen (5 girls) healthy children ages 9/10 (mean = 10.13, SD = +/- 0.51) years at initial and 11 to 13 (mean = 12.28, SD = +/- 0.62) years at follow-up. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: All-night polysomnography was performed at each assessment and sleep stages were scored with Rechtschaffen and Kales criteria. Slow wave sleep minutes decreased from the initial to the follow-up session by 29%, while minutes of stage 2 increased by 17%. NREM and REM sleep EEG spectra from two central and two occipital leads were examined for developmental changes. All-night analyses showed a significant decrease of EEG power from the initial to follow-up session across a range of frequencies during NREM and REM sleep. This decline occurred across leads and states in the delta/theta bands (3.8 - 7 Hz). Time-frequency analyses indicated that this effect was consistent across the night. The decline in power with age was most pronounced in the left central and right occipital leads. The frequency of greatest power in the sigma band (11 - 16 Hz) was significantly higher at follow-up. CONCLUSIONS: This longitudinal analysis highlights asymmetrical frequency-specific declines in sleep EEG spectral power with early adolescent maturation, which may reflect early signs of the cortical synaptic pruning in the healthy adolescent.