Adolescent sedentary behavior and body composition in early adulthood: results from a cohort study.

BACKGROUND: This study investigates the cross-sectional and prospective associations between accelerometer-measured sedentary behavior and body composition from adolescence to early adulthood. METHODS: Data from the Santiago Longitudinal Study were analyzed (n = 212). Sedentary time was measured at age 16 years, and body composition (body mass index [BMI], waist circumference, waist-to-height ratio [WHtR], fat mass percentage, and lean mass percentage) was examined at both age 16 and 23 years. Adjusted linear regression models estimated associations between sedentary time, sedentary bout duration, and body composition, overall and by sex. RESULTS: In all analyses, mean sedentary bout duration was not associated with body composition. In cross-sectional analyses, more sedentary time during adolescence was significantly associated with lower BMI, waist circumference, WHtR, fat mass percentage, and higher lean mass percentage (p < 0.05). One standard deviation increase in daily sedentary time was prospectively associated with lower body mass index (ß = -1.22 kg/m2, 95% CI: -2.02, -0.42), waist circumference (ß = -2.39 cm, 95% CI: -4.03, -0.75), and WHtR (ß = -0.014, 95% CI: -0.024, -0.004). Sedentary time at 16 years was not associated with changes in body composition from 16 to 23 years. CONCLUSIONS: Sedentary behavior in adolescence is not adversely associated with body composition profiles in early adulthood. IMPACT: Little is known about the effect of device-measured sedentary behavior on body composition during the transition from adolescence to early adulthood. Among participants in the Santiago Longitudinal Study, more accelerometer-measured sedentary time during adolescence was associated with lower BMI, waist circumference, and waist-to-height ratio in early adulthood though point estimates were generally small in magnitude. Sedentary behavior in adolescence was not detrimentally associated with healthy body composition profiles in early adulthood. Public health interventions aimed at reducing obesity rates could consider other behaviors, such as physical activity and healthy diet, instead of sitting time.

Iron supplementation given to nonanemic infants: neurocognitive functioning at 16 years.

OBJECTIVE: There is concern that high iron uptake during the critical period of early brain development carries potential risks, especially for nonanemic infants. This study examined the neurocognitive functioning of 16-year-olds who were nonanemic as infants and received iron supplementation. METHODS: We studied 562 Chilean adolescents (M 16.2 years; 52.7% female) who participated in a randomized controlled iron supplementation trial in infancy. Between 6 and 12 months, 346 consumed an iron-fortified formula (12.7 Fe mg/L) or, if primarily breastfed, liquid vitamins with 15 mg elemental iron as ferrous sulfate, and 216 consumed unmodified cow milk without iron or liquid vitamins without iron if primarily breastfed. RESULTS: Compared to adolescents in the no-added iron condition in infancy, those in the iron-supplemented condition had poorer visual-motor integration, quantitative reasoning skills, and incurred more errors on neurocognitive tasks. Consuming larger amounts of iron-fortified formula in infancy was associated with lower arithmetic achievement. Of adolescents who had high hemoglobin at 6 months (Hb ≥ 125 g/L), those in the iron supplemented condition had poorer performance on arithmetic, quantitative reasoning, and response inhibition tests than those in the no-added iron condition. Of adolescents who had marginally low 6-month hemoglobin (Hb > 100 and < 110 g/L), those who received no-added iron incurred more errors on a visual searching task than those in the iron-supplemented condition. CONCLUSION: The physiologic need for iron during the period of rapid and critical brain development in young infants should be considered vis-à-vis the risks associated with supplementing nonanemic infants with high levels of iron.Clinical Trials number: NCT01166451.

Early-life adversity is associated with poor iron status in infancy.

Exposure to early-life adversity (ELA) and iron deficiency early in life are known risk factors for suboptimal brain and socioemotional development. Iron deficiency may arise from and co-occur with ELA, which could negatively affect development. In the present study, we investigated whether ELA is associated with iron deficiency in infants receiving no iron supplementation. This study is a secondary analysis of extant data collected in the 1990s; participants were healthy infants from working-class communities in Santiago, Chile (N = 534, 45.5% female). We measured stressful life events, maternal depression, and low home support for child development during infancy and assessed iron status when the infant was 12 months old. Slightly more than half of the infants were iron-deficient (51%), and 25.8% were iron-deficient anemic at 12 months. Results indicated that ELA was associated with lower iron levels and iron deficiency at 12 months. The findings are consistent with animal and human prenatal models of stress and iron status and provide evidence of the association between postnatal ELA and iron status in humans. The findings also highlight a nutritional pathway by which ELA may impact development and present a nutritionally-focused avenue for future research on ELA and psychopathology.

Iron Deficiency in Infancy and Sluggish Cognitive Tempo and ADHD Symptoms in Childhood and Adolescence.

OBJECTIVE: To determine whether iron deficiency in infancy is associated with sluggish cognitive tempo (SCT) or attention-deficit/hyperactive-impulsive (AD-HI) symptoms in childhood and adolescence, and whether such behaviors contribute concurrently and predictively to lower verbal and mathematical abilities. METHOD: Chilean children (N = 959; 50% male, of Spanish or indigenous descent from working-class backgrounds) were rated by mothers for SCT or AD-HI symptoms at ages 5, 10, and 16 years. Children completed standardized tests assessing verbal and mathematical abilities at ages 5, 10, and 16. At ages 12 and 18 months, children were assessed for iron deficiency. RESULTS: Adjusting for a comprehensive panel of covariates, greater severity of iron deficiency in infancy was associated with more frequent SCT and AD-HI symptoms at all ages studied. Most effects of iron deficiency on children's verbal and math skills were indirect, mediated through AD-HI behaviors. Children's AD-HI symptoms related to lower verbal and math test scores within age and across age. CONCLUSIONS: The long-term associations found between infant iron deficiency and SCT and AD-HI behaviors suggest that the neurodevelopmental alterations that stem from postnatal iron deficiency might play an etiological role in the development of ADHD. Screening for early-life nutritional deficiencies among children with SCT or ADHD symptoms might prove useful, and behavioral screening of children with a history of iron deficiency seems warranted. Interventions that support brain development after early nutritional deprivation also would be beneficial.

Young adult outcomes associated with lower cognitive functioning in childhood related to iron-fortified formula in infancy.

Objective: This study examined how the lower cognitive skills in children who consumed iron-fortified formula in infancy relate to outcomes in young adulthood.Methods: Participants were 443 Chilean young adults (M age = 21.2y, 55% female) who took part in a randomized controlled iron-deficiency anemia preventive trial during infancy (6-12 m). Slightly over half of participants (n = 237) received iron-fortified formula (12.7 mg/L) and 206 received a low-iron formula (2.3 mg/L). Spatial memory, IQ, and visual-motor integration were measured at age 10, and neurocognition, emotion regulation, educational level, and attainment of adult developmental milestones were assessed at age 21.Results: Consumption of iron-fortified formula in infancy was associated with poorer performance on neurocognitive tests in childhood, and these effects related to poorer neurocognitive, emotional, and educational outcomes in young adulthood. Dosage effects associated with consumption of iron-fortified formula were found for lower educational attainment and, marginally, slower mental processing. Those who received iron-fortified formula and had low age 10 cognitive abilities performed most poorly on neurocognitive tests at age 21.Conclusion: Findings suggest that the long-term development of infants who consume iron-fortified formula may be adversely affected.Clinical Trials number: NCT01166451.

Adolescent Internalizing, Externalizing, and Social Problems Following Iron Deficiency at 12-18 Months: The Role of Maternal Responsiveness.

This study tested whether maternal responsiveness moderated or mediated pathways from iron deficiency (ID) at 12-18 months to adolescent behavior problems. Participants were part of a large Chilean cohort (N = 933). Iron status was assessed at 12 and 18 months. Maternal responsiveness was assessed at 9 months and 5 years. Parents reported their child's symptomology at 5 years, 10 years, and adolescence (11-17 years; M = 14.4). Structural equation modeling identified a previously unrecognized pathway by which child externalizing problems and negative maternal responsiveness at 5 years mediated associations between ID at 12-18 months and adolescent internalizing, externalizing, and social problems. Positive maternal responsiveness in infancy did not buffer those with ID anemia from developing 5-year internalizing problems.

Sensitive periods for psychosocial risk in childhood and adolescence and cardiometabolic outcomes in young adulthood.

Greater psychosocial risk in childhood and adolescence predicts poorer cardiometabolic outcomes in adulthood. We assessed whether the timing of psychosocial risk from infancy through adolescence predicts cardiometabolic outcomes in young adulthood. Young adults and their mothers participated in a longitudinal study beginning in infancy in Santiago, Chile (N = 1040). At infancy, 5 years, 10 years, and adolescence, mothers reported on depressive symptoms, stressful experiences, support for child development in the home, father absence, parental education, and socioeconomic status (SES) to create a psychosocial risk composite at each time point. Young adults (52.1% female; 21-27 years) provided fasting serum samples and participated in anthropometric and blood pressure (BP) assessments, including a dual-energy X-ray absorptiometry (DXA) scan for measuring body fat. Greater infant psychosocial risk was associated with a greater young adult metabolic syndrome score (ß = 0.07, 95% confidence intervals (CI): 0.01 to 0.13, p = 0.02), a higher body mass index and waist circumference composite (ß = 0.08, 95% CI: 0.03 to 0.13, p = 0.002), and a higher body fat (DXA) composite (ß = 0.07, 95% CI: 0.01 to 0.12, p = 0.02). No psychosocial risk measure from any time point was associated with BP. Infant psychosocial risk predicted cardiometabolic outcomes in young adulthood better than psychosocial risk at 5 years, 10 years, or adolescence, mean of psychosocial risk from infancy through adolescence, and maximum of psychosocial risk at any one time. Consistent with the Developmental Origins of Health and Disease model, findings suggest that infancy is a sensitive period for psychosocial risk leading to poorer cardiometabolic outcomes in young adulthood.

Risk taking, sensation seeking and personality as related to changes in substance use from adolescence to young adulthood.

INTRODUCTION: This study examined changes in substance use from adolescence to young adulthood as related to adolescents' risk taking, sensation seeking, antisocial activities, and personality traits. METHODS: Chilean youth (N = 890, 52% female) were studied in adolescence (14.5 and 16.2 years) and young adulthood (M age 21.3 years). Risk taking was assessed via a laboratory-based performance task (Balloon Analogue Risk Task), and self-administered questionnaires assessed sensation seeking, antisocial behaviors, personality and substance use. RESULTS: Frequent involvement in sensation seeking and antisocial activities were associated with increased odds of continued marijuana use from adolescence to young adulthood and of illicit substance use at young adulthood. High risk taking was associated with a reduced likelihood of discontinuing marijuana use at young adulthood, and high agreeableness and conscientiousness were associated with reduced likelihood of new onset marijuana use and illicit substance use at young adulthood. CONCLUSIONS: Results highlight specific risk-taking tendencies and personality characteristics that relate to initiating, continuing, or discontinuing substance use at entry into adulthood. Sensation seeking and involvement in antisocial activities were the two foremost risk factors for continued use, which is a forecaster of drug dependence. Findings suggest potential prevention and intervention targets for abstaining from or discontinuing substance use as youth transition to adulthood.

Associations Among Household Chaos, School Belonging and Risk Behaviors in Adolescents.

We examined the associations between adolescent risk behaviors and household chaos, and whether associations varied by adolescents' sense of school belonging. We collected data from 801 Chilean adolescents from working-class families (M age 16.2 years). Approximately, one-quarter of participants reported past-month cigarette use, and 8% and 9% reported past-month binge drinking and marijuana use, respectively. More than half of youth reported having sex (52%), 23% of youth reported having unprotected sex at their last encounter, and 14% reported having multiple sex partners. Within the past year, 16%, 36%, and 23% reported carrying a weapon, physically attacking someone, and threatening to physically hurt someone, respectively. Greater household chaos was related to increased odds of each risk behavior except unprotected sex. These associations did not vary significantly by level of school belonging. Results are compared to previously reported results using a U.S., largely Latinx sample in attempts to replicate findings across culture and context.

Associations Among Mothers' Depression, Emotional and Learning-Material Support to Their Child, and Children's Cognitive Functioning: A 16-Year Longitudinal Study.

This study examined the associations among maternal depression, mothers' emotional and material investment in their child, and children's cognitive functioning. Middle-class Chilean mothers and children (N = 875; 52% males) were studied when children were 1, 5, 10, and 16 years (1991-2007). Results indicated that highly depressed mothers provided less emotional and material support to their child across all ages, which related to children's lower IQ. Children with lower mental abilities at age 1 received less learning-material support at age 5, which led to mothers' higher depression at child age 10. Mothers' low support was more strongly linked to maternal depression as children got older. Findings elucidate the dynamic and enduring effects of depression on mothers' parenting and children's development.

Effect of Infant Iron Deficiency on Children's Verbal Abilities: The Roles of Child Affect and Parent Unresponsiveness.

BACKGROUND: Infants who are iron-deficient anemic seek and receive less stimulation from their caregivers, predisposing such children to be functionally isolated. OBJECTIVES: To test the sequence whereby iron deficiency in infancy contributes to children's disengagement from the environment, which reduces parent stimulation which, in turn, contributes to children's poor verbal skills. METHODS: Chilean children (N = 875, 54% male) were studied, 45% of whom were iron deficient or iron-deficient anemic in infancy. We used structural equation modeling to test the sequence outlined above and to examine the effect of infant iron status on children's verbal performance at ages 5 and 10 years including the roles of child and parent intermediate variables. RESULTS: Severity of iron deficiency in infancy was associated with higher levels of children's dull affect and social reticence at 5 years (ß = .10, B = .26, SE = .12, p < .05), and these behaviors were associated with parent unresponsiveness (ß = .29, B = .13, SE = .03, p < .001), which related to children's lower verbal abilities at age 5 (ß = - .29, B = - 2.33, SE = .47, p < .001) and age 10 (ß = - .22, B = - 3.04, SE = .75, p < .001). An alternate model where poor iron status related directly to children's verbal ability was tested but not supported. CONCLUSIONS: Findings support functional isolation processes resulting from a nutritional deficiency, with iron-deficient anemic infants showing affective and behavioral tendencies that limit developmentally stimulating caregiving which, in turn, hinder children's verbal abilities.

Associations Among Infant Iron Deficiency, Childhood Emotion and Attention Regulation, and Adolescent Problem Behaviors.

This study examined whether iron deficiency (ID) in infancy contributes to problem behaviors in adolescence through its influence on poor regulatory abilities in childhood. Chilean infants (N = 1,116) were studied when there was no national program for iron fortification (1991-1996), resulting in high rates of ID (28%) and iron-deficiency anemia (IDA, 17%). Infants (54% male) were studied at childhood (Mage  = 10 years) and adolescence (Mage  = 14 years). IDA in infancy was related to excessive alcohol use and risky sexual behavior in adolescence through its effect on poor emotion regulation in childhood. Attentional control deficits at age 10 were also related to both infant IDA and heightened risk taking in adolescence. Findings elucidate how poor childhood regulatory abilities associated with infant IDA compromise adjustment in adolescence.

Risk and protective factors for sexual and dating violence victimization: a longitudinal, prospective study of Latino and African American adolescents.

Teen dating violence and sexual victimization are serious public health concerns. Although research has highlighted the correlates and consequences of such abuse, little is known about early antecedents. The current study sought to identify the risk and protective factors evident in early adolescence that are associated with sexual and dating violence victimization in late adolescence. The sample involved 236 (52% female) low-income Latino (69%) and African American (31%) youth, their older sisters, and their mothers who were studied when youth were, on average, ages 13 and 18 years. The results indicated that early indicators of a risky lifestyle (e.g., getting drunk, having sex) and having deviant friends and siblings were associated with a higher likelihood of subsequent victimization. Mothers' early strictness, monitoring, and conservative sexual attitudes predicted a lower likelihood of subsequent assault and served as significant buffers given specific risks, particularly for girls and Latinos. The findings suggest that behavior and social network patterns established relatively early in life increase one's vulnerability to victimization later in life, as well as point to aspects of parenting that serve a protective function against such outcomes.

Associations between Adolescent Alcohol Use and Neurocognitive Functioning in Young Adulthood.

This study examined the associations between excessive alcohol intake during adolescence and neurocognitive functioning in young adulthood and whether these relations varied by sex. Participants were working-class Chilean adolescents (N = 692; Mage 16.0 years; 54.5% female) who provided frequency of past 30-day bingeing and past-year intoxication. Neurocognitive measures were completed in young adulthood (Mage 21.2 years). Illicit substance users were excluded a priori and other substance use was controlled. When males and females were considered simultaneously, no main effects of intoxication or bingeing were found. However, several sex-specific effects emerged for intoxication, such that more frequent intoxication was associated with poorer visual memory, attention, processing speed, response inhibition, and cognitive flexibility in females, while frequent intoxication related to better attention and processing speed in males. In general, effect sizes were small. No relations emerged for verbal memory, working memory, or spatial learning. Possible factors that contribute to divergent sex effects are discussed.

Sibling Caretaking Among Mexican American Youth: Conditions That Promote and Hinder Personal and School Success.

This study examined how Mexican American youths' extent of sibling caretaking is related to their personal and school adjustment, and whether mothers' gender-role attitudes and youths' familistic beliefs moderate these associations. One hundred and ninety-five Mexican American youth (M age 14.8 years; 64% girls) and their mothers participated in the study. Youth completed questionnaires about their extent of sibling caretaking, their educational aspirations, school involvement, school absences, grades, and their prosocial tendencies. Results indicated that, when examined singly, frequent sibling caretaking was related to youths' higher educational aspirations, greater prosocial tendencies, and more school engagement for older youth, but also to more school absences. When extensive sibling care was coupled with mothers' sex-stereotyped attitudes, youth experienced poorer outcomes. Youth who held strong familistic beliefs and were highly involved in sibling care reported lower educational aspirations, particularly girls. Findings underscore the importance of considering socialization influences when evaluating associations between sibling caretaking and youths' development.

Breastfeeding Duration and Timing of Bottle Supplementation: Associations with Body Mass Index from Childhood to Young-Adulthood.

Evidence for the association between breastfeeding (BF) duration and later body mass index (BMI) is inconsistent. We explored how BF duration and BF type (exclusive or partial) related to BMI from childhood to young adulthood in a Chilean cohort. Infants were recruited at 6 months between 1994 and 1996 in Santiago, Chile (n = 821). Mothers reported date of first bottle and last BF; anthropometry was measured at 1, 5, 10, 16, and 23 years. We tested whether: (1) type of BF at 6 months (none, partial, exclusive) and (2) duration of exclusive BF (<1 month, 1 to <3 months, 3 to <6 months, and ≥6 months) related to BMI. At 6 months, 35% received both breastmilk and formula ("partial BF") and 38% were exclusively breastfed. We found some evidence of an association between longer BF and lower BMI z-scores at young ages but observed null effects for later BMI. Specifically, BF for 3 to <6 months compared to <1 month related to lower BMI z-scores at 1 and 5 years (both p < 0.05). Our results are in partial accordance with others who have not found a protective effect of longer BF for lower BMI.

Socioeconomic position and executive functioning from childhood to young adulthood: Evidence from Santiago, Chile.

BACKGROUND: Optimizing cognitive development through early adulthood has implications for population health. This study aims to understand how socioeconomic position (SEP) across development relates to executive functioning. We evaluate three frameworks in life-course epidemiology - the sensitive period, accumulation, and social mobility hypotheses. METHODS: Participants were young adults from Santiago, Chile who were studied from 6 months to 21 years. Family SEP was measured at ages 1 y, 10 y, and 16 y with the modified Graffar Index. Executive functioning was assessed at ages 16 y and 21 y by the Trail Making Test Part B (Trails B). Analyses estimating 16 y and 21 y executive function involved 581 and 469 participants, respectively. Trails B scores were modeled as a function of SEP at 1 y, 10 y, and 16 y, as the total accumulation of disadvantage, and as change in SEP between 1 y and 10 y and between 10 y and 16 y. RESULTS: Participants were low- to middle-income in infancy and, on average, experienced upwards mobility across childhood. Half of participants (58%) improved Trails B scores from 16 y and 21 y. Most (68%) experienced upward social mobility between infancy and 16 y. When examined independently, worse SEP measured at 10 y and 16 y related to worse (longer time to complete) Trails B scores at Age 21 but did not relate to the other outcomes. After mutual adjustment as a test of the sensitivity hypothesis, no SEP measure was independently related to any outcome. Testing the accumulation hypothesis, cumulative low SEP was associated with worse cognitive performance at 21 y (ß = 3.6, p = 0.04). Results for the social mobility hypothesis showed no relation to cognitive scores or to change in cognitive scores. Comparing all hypotheses, SEP at 16 y explained the most variability in executive functioning at 21 y, providing support for the sensitive period hypothesis. CONCLUSIONS: Results indicate that experiencing cumulatively low socioeconomic position from infancy to adolescence can have a negative impact on cognitive functioning in young adulthood. Findings also provide evidence in support of adolescence as a key developmental period during which SEP can most strongly impact cognitive functioning.

The younger siblings of childbearing adolescents: parenting influences on their academic and social-emotional adjustment.

The younger siblings of childbearing adolescents have poorer school outcomes and exhibit more internalizing and externalizing problems compared to their peers without a childbearing sister. We test a model where living with an adolescent childbearing sister constitutes a major family stressor that disrupts mothers' parenting and well-being, and through which, adversely affect youths' adjustment. Data came from 243 Latino younger siblings (62% female, M age 13.7 years) and their mothers, 121 of whom lived with a childbearing adolescent sister and 122 of whom did not. Individual fixed-effects models controlled for earlier measures of each respective model construct, thereby reducing omitted variable bias from pre-existing group differences. Results show that, for boys, the relationship between living with a childbearing adolescent sister and youth outcomes was sequentially mediated through mothers' stress and parenting (i.e., monitoring and nurturance). For girls, however, the relationship was mediated through mothers' monitoring only. Findings elucidate the within-family processes that contribute to the problematic outcomes of youth living with childbearing adolescent older sisters.

Associations between adverse home environments and appetite hormones, adipokines, and adiposity among Chilean adolescents.

Little is known regarding the relationship between adverse home environments and hormones important in regulation of appetite and their impact on obesity in children and adolescents. In this study, we examined the impact of socioeconomic economic status, family stress and maternal depressive symptoms on appetite hormones, adipokines and adiposity. To determine whether adverse home environments in childhood and adolescence relate to adiposity in adolescence and disruptions in appetite hormones and adipokines, specifically lower levels of adiponectin and ghrelin and elevated levels of leptin and orexin. Adversity in the home (maternal depressive symptoms, family stress, socioeconomic disadvantage) was measured in the households of 593 Chilean youth at age 10 years (52.3% male) and in 606 youth at 16 years. At 16 years, participants provided fasting blood samples for assessment of adipokines and appetite hormones. Waist-to-height ratio was used to assess central adiposity. Correlational analyses examined associations between continuous levels of adversity in childhood and adolescence and appetite hormones and adiposity in adolescence. Multinomial logistic regressions compared hormone levels by tertiles of adversity. Participants were 52% male, with average age at the 16 years hormone assessment being 16.8 (n = 606, SD = 0.26). Those with highest maternal depression at age 10 had lower adiponectin OR = 0.95 [95% CI: 0.91, 0.99], p = 0.005) and ghrelin levels (OR = 0.98 [95% CI: 0.98, 1.00), p = 0.022) than those in the lowest maternal depression group at age 16. Those with the highest family stress at 16 years had lower adiponectin levels (OR = 0.93 [95% CI: 0.89, 0.98), p = 0.004) and higher central adiposity (OR = 1.05 [1.01, 1.08], p = 0.009) than the lowest family stress group. There were no significant associations found between socioeconomic status at either 10 or 16 years and appetite hormones. Results add new evidence regarding the relationship between household adversity to appetite hormones and adipokines, with the most consistent results for adiponectin. Current findings suggest that the relationship between home environment and adipokines and appetite hormones may play a role in altered adiposity in children and adolescents.

Effects of Adolescent Childbearing on Latino Siblings: Changes in Family Dynamics and Feelings Toward the Teen Mother.

Latinos have had the highest teenage birthrate of any racial or ethnic group in the United States for the past 15 years, yet little is known about how Latino families are affected by a teenage daughter's childbearing. In-depth interviews were conducted with 32 Mexican American younger siblings of parenting teens to discern how their sister's childbearing had affected them and their families. The most commonly reported negative effects were increased family stress and conflict, more arguments with the parenting older sister, and less time spent with family members. Regarding benefits, all youth described a loving bond with their sister's baby, two thirds described their family becoming closer, and 81% felt closer to their older sister. The implications of these effects for Mexican American families are discussed.