Family environments, adrenarche, and sexual maturation: a longitudinal test of a life history model

How does childhood socioeconomic hardship affect reproductive strategy? Pathways of development

Objectives

In high‐income populations, evidence suggests that socioeconomic disadvantage early in life is correlated with reproductive strategy. Children growing up in unfavorable rearing environments tend to experience earlier sexual maturity and first births. Earlier first births may be associated with higher fertility, but links between socioeconomic disadvantage and larger family size have rarely been tested. The pathways through which early disadvantage influences reproduction are unknown. We test whether physiological factors link childhood adversity to age at first birth and total children.

Methods

Using data from the Newcastle Thousand Families Study, a 1947 British birth cohort, we developed path models to identify possible physiological traits linking childhood socioeconomic status, and poor housing standards, to two reproductive outcomes: age at first birth and total children. We explored birth weight, weight gain after birth, childhood illnesses, body mass index at age 9, age at menarche, and adult height as possible mediators.

Results

We found direct, negative effects of socioeconomic status (SES) and housing on age at first birth, and of housing on fertility. Although we found links between childhood disadvantage and menarche and height, neither of these were significantly correlated with either reproductive outcome. Age at first birth completely mediates the relationship between childhood adversity and total fertility, which we believe has not been empirically demonstrated before.

Conclusions

While there are some links between childhood adversity and child health, we find little evidence that physiological pathways, such as child health and growth, link early childhood adversity to reproductive outcomes in this relatively well‐nourished population. Am. J. Hum. Biol. 28:356–363, 2016. © 2015 The Authors American Journal of Human Biology Published by Wiley Periodicals, Inc.

Neuroendocrine coupling across adolescence and the longitudinal influence of early life stress

Drawing on conceptual models illustrating the advantages of a multisystemic, interactive, developmental approach to understanding development, the present study examines the covariation of stress and sex hormones across the adolescent transition and the effect of early life stress (ELS) on neuroendocrine coupling to gain insight into atypical development. Morning levels of cortisol, testosterone, and dehydroepiandrosterone (DHEA) were assessed at ages 11, 13, and 15; ELS was assessed during the infancy and preschool periods. Hierarchical linear modeling revealed that cortisol-DHEA coupling patterns progressed to tight, positive coupling across adolescence. Cortisol-testosterone coupling was positive at age 11 but became more negative at ages 13 and 15. Exposure to ELS resulted in more adultlike neuroendocrine coupling patterns earlier in life than non-exposed youth; however the effect of ELS on cortisol-testosterone coupling was unique to girls. Results illustrate trajectories of neuroendocrine coupling that may be unique to adolescence. Moderation by ELS suggests that early stress exposure may prompt earlier adultlike neuroendocrine coupling, particularly within girls, which may contribute to early pubertal development.

Father absence and reproduction-related outcomes in Malaysia, a transitional fertility population

Father absence is consistently associated with children’s reproductive outcomes in industrialized countries. It has been suggested that father absence acts as a cue to particular environmental conditions that influence life history strategies. Much less is known, however, about the effects of father absence on such outcomes in lower-income countries. Using data from the 1988 Malaysian Family Life Survey (n = 567), we tested the effect of father absence on daughters’ age at menarche, first marriage, and first birth; parity progression rates; and desired completed family size in Malaysia, a country undergoing an economic and fertility transition. Father absence during later childhood (ages 8 to 15), although not during earlier childhood, was associated with earlier progressions to first marriage and first birth, after controlling for other confounders. Father absence does not affect age at menarche, desired family size, or progression from first to second birth. The patterns found in this transitional population partly mirror those in developed societies, where father absence accelerates reproductive events. There is, however, a notable contrast between the acceleration in menarche for father-absent girls consistently found in developed societies and the lack of any association in our findings. The mechanisms through which father absence affects reproduction may differ in different ecological contexts. In lower-income contexts, direct paternal investment or influence may be of more importance in determining reproductive behavior than whether fathers act as a cue to environmental conditions.

Early adversity, elevated stress physiology, accelerated sexual maturation, and poor health in females

Evolutionary-minded developmentalists studying predictive-adaptive-response processes linking childhood adversity with accelerated female reproductive development and health scientists investigating the developmental origins of health and disease (DOoHaD) may be tapping the same process, whereby longer-term health costs are traded off for increased probability of reproducing before dying via a process of accelerated reproductive maturation. Using data from 73 females, we test the following propositions using path analysis: (a) greater exposure to prenatal stress predicts greater maternal depression and negative parenting in infancy, (b) which predicts elevated basal cortisol at 4.5 years, (c) which predicts accelerated adrenarcheal development, (d) which predicts more physical and mental health problems at age 18. Results prove generally consistent with these propositions, including a direct link from cortisol to mental health problems. DOoHaD investigators should consider including early sexual maturation as a core component linking early adversity and stress physiology with poor health later in life in females.

Methodologically sound: Evaluating the psychometric approach to the assessment of human life history [reply to Copping, Campbell, and Muncer, 2014]

Copping, Campbell, and Muncer (2014) have recently published an article critical of the psychometric approach to the assessment of life history (LH) strategy. Their purported goal was testing for the convergent validation and examining the psychometric structure of the High-K Strategy Scale (HKSS). As much of the literature on the psychometrics of human LH during the past decade or so has emanated from our research laboratory and those of close collaborators, we have prepared this detailed response. Our response is organized into four main sections: (1) A review of psychometric methods for the assessment of human LH strategy, expounding upon the essence of our approach; (2) our theoretical/conceptual concerns regarding the critique, addressing the broader issues raised by the critique regarding the latent and hierarchical structure of LH strategy; (3) our statistical/methodological concerns regarding the critique, examining the validity and persuasiveness of the empirical case made specifically against the HKSS; and (4) our recommendations for future research that we think might be helpful in closing the gap between the psychometric and biometric approaches to measurement in this area. Clearly stating our theoretical positions, describing our existing body of work, and acknowledging their limitations should assist future researchers in planning and implementing more informed and prudent empirical research that will synthesize the psychometric approach to the assessment of LH strategy with complementary methods.

Pubertal timing and sexual risk behaviors among rural African American male youth: testing a model based on life history theory

Life History Theory (LHT), a branch of evolutionary biology, describes how organisms maximize their reproductive success in response to environmental conditions. This theory suggests that challenging environmental conditions will lead to early pubertal maturation, which in turn predicts heightened risky sexual behavior. Although largely confirmed among female adolescents, results with male youth are inconsistent. We tested a set of predictions based on LHT with a sample of 375 African American male youth assessed three times from age 11 to age 16. Harsh, unpredictable community environments and harsh, inconsistent, or unregulated parenting at age 11 were hypothesized to predict pubertal maturation at age 13; pubertal maturation was hypothesized to forecast risky sexual behavior, including early onset of intercourse, substance use during sexual activity, and lifetime numbers of sexual partners. Results were consistent with our hypotheses. Among African American male youth, community environments were a modest but significant predictor of pubertal timing. Among those youth with high negative emotionality, both parenting and community factors predicted pubertal timing. Pubertal timing at age 13 forecast risky sexual behavior at age 16. Results of analyses conducted to determine whether environmental effects on sexual risk behavior were mediated by pubertal timing were not significant. This suggests that, although evolutionary mechanisms may affect pubertal development via contextual influences for sensitive youth, the factors that predict sexual risk behavior depend less on pubertal maturation than LHT suggests.

Dual-axis hormonal covariation in adolescence and the moderating influence of prior trauma and aversive maternal parenting

Adversity early in life can disrupt the functioning of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes and increase risk for negative health outcomes. The interplay between these axes and the environment is complex, and understanding needs to be advanced by the investigation of the multiple hormonal relationships underlying these processes. The current study examined basal hormonal associations between morning levels of cortisol, testosterone, and dehydroepiandrosterone in a cohort of adolescents (mean age 15.56 years). The moderating influence of childhood adversity was also examined, as indexed by self-reported trauma (at mean age 14.91), and observed maternal aggressive parenting (at mean age 12.41). Between-person regressions revealed significant associations between hormones that were moderated by both measures of adversity. In females, all hormones positively covaried, but also interacted with adversity, such that positive covariation was typically only present when levels of trauma and/or aggressive parenting were low. In males, hormonal associations and interactions were less evident; however, interactions were detected for cortisol-testosterone - positively covarying at high levels of aggressive parenting but negatively covarying at low levels - and DHEA-cortisol - similarly positively covarying at high levels of parental aggression. These results demonstrate associations between adrenal and gonadal hormones and the moderating role of adversity, which is likely driven by feedback mechanisms, or cross-talk, between the axes. These findings suggest that hormonal changes may be the pathway through which early life adversity alters physiology and increases health risks, but does so differentially in the sexes; however further study is necessary to establish causation.

Associations between early adrenarche, affective brain function and mental health in children

Early timing of adrenarche, associated with relatively high levels of Dehydroepiandrosterone (DHEA) in children, has been associated with mental health and behavioral problems. However, little is known about effects of adreneracheal timing on brain function. The aim of this study was to investigate the effects of early adrenarche (defined by high DHEA levels independent of age) on affective brain function and symptoms of psychopathology in late childhood (N = 83, 43 females, M age 9.53 years, s.d. 0.34 years). Results showed that higher DHEA levels were associated with decreased affect-related brain activity (i) in the mid-cingulate cortex in the whole sample, and (ii) in a number of cortical and subcortical regions in female but not male children. Higher DHEA levels were also associated with increased externalizing symptoms in females, an association that was partly mediated by posterior insula activation to happy facial expressions. These results suggest that timing of adrenarche is an important moderator of affect-related brain function, and that this may be one mechanism linking early adrenarche to psychopathology.

The association of puberty and young adolescent alcohol use: do parents have a moderating role?

PURPOSE

To explore the extent to which parent-adolescent emotional closeness, family conflict, and parental permissiveness moderate the association of puberty and alcohol use in adolescents (aged 10-14).

METHODS

Cross-sectional survey of 7631 adolescents from 231 Australian schools. Measures included pubertal status, recent (30day) alcohol use, parent-adolescent emotional closeness, family conflict, parental permissiveness of alcohol use and peer alcohol use. The analysis was based on a two-level (individuals nested within schools) logistic regression model, with main effects entered first, and interaction terms added second.

RESULTS

The interaction of family factors and pubertal stage did not improve the fit of the model, so a main effect model of family factors and pubertal stage was adopted. There were significant main effects for pubertal stage with boys in middle puberty at increased odds of alcohol use, and girls in advanced puberty at increased odds of alcohol use.

CONCLUSIONS

Puberty and family factors were strong predictors of adolescent alcohol use, but family factors did not account for variation in the association of pubertal stage and alcohol use.

Experiences in the military may impact dual-axis neuroendocrine processes in veterans

Military stressors such as survival training can affect endocrine functioning in the short term, and combat has been associated with endocrine changes linked to psychopathology. However, studies with military samples examining whether there are individual differences in these changes as part of normal development, or as an adaptive mechanism in adulthood are lacking. This study examined whether exposure to combat in a sample of veterans was associated with differential endocrine activity to a laboratory frustration task. Results indicated that Army veterans demonstrated significant testosterone reactivity to frustration and negative coupling between cortisol and testosterone. Alternatively, Navy and Marine veterans demonstrated little testosterone reactivity to frustration and positive coupling between cortisol and testosterone. Positive cortisol-testosterone coupling was stronger among individuals who had more dangerous combat experiences. This latter pattern may better prepare individuals for stressful life experiences and supports the contention that adulthood stressors may calibrate endocrine systems. Results are explained in the context of the Adaptive Calibration Model (Ellis et al., 2012, Developmental Psychology, 48(3), 598-623) which proposes that exposure to key environmental dimensions during endocrinologically malleable life stages (e.g., puberty) can change stress responsivity, resulting in a faster life history trajectory (e.g., increased risk-taking and aggression).

Growing up or growing old? Cellular aging linked with testosterone reactivity to stress in youth

BACKGROUND

Given the established relation between testosterone and aging in older adults, we tested whether buccal telomere length (TL), an established cellular biomarker of aging, was associated with testosterone levels in youth.

METHODS

Children, mean age 10.2 years, were recruited from the greater New Orleans area, and salivary testosterone was measured diurnally and during an acute stressor. Buccal TL was measured using monochrome multiplex quantitative real-time polymerase chain reaction. Testosterone and TL data were available on 77 individuals. The association between buccal TL and testosterone was tested using multivariate generalized estimating equations to account for clustering of children within families.

RESULTS

Greater peak testosterone levels (β = -0.87, P < 0.01) and slower recovery (β = -0.56, P < 0.01) and reactivity (β = -1.22, P < 0.01) following a social stressor were significantly associated with shorter buccal TL after controlling for parental age at conception, child age, sex, sociodemographic factors and puberty. No association was initially present between diurnal measurements of testosterone or morning basal testosterone levels and buccal TL. Sex significantly moderated the relation between testosterone reactivity and buccal TL.

CONCLUSIONS

The association between testosterone and buccal TL supports gonadal maturation as a developmentally sensitive biomarker of aging within youth. As stress levels of testosterone were significantly associated with buccal TL, these findings are consistent with the growing literature linking stress exposure and accelerated maturation. The lack of association of diurnal testosterone or morning basal levels with buccal TL bolsters the notion of a shared stress-related maturational mechanism between cellular stress and the hypothalamic pituitary gonadal axis. These data provide novel evidence supporting the interaction of aging, physiologic stress and cellular processes as an underlying mechanism linking negative health outcomes and early life stress.

Early menarche predicts increased depressive symptoms and cortisol levels in Quebec girls ages 11 to 13

Earlier age of menarche is believed to confer greater vulnerability to depressive symptoms via increased reactivity to stressors associated with adolescence. In this longitudinal study, we measured depressive symptoms and salivary cortisol levels in 198 boys and 142 girls between the ages of 11 and 13 tested four times during Grade 7 as they transitioned from elementary school to secondary school as per Quebec's education system. Results showed that girls who had already reached menarche before starting secondary school had significantly higher depressive symptoms and salivary cortisol levels across the school year in comparison to girls who had not reached menarche, who in turn presented higher depressive scores than boys. When we divided menarcheal girls as a function of menarcheal timing in subanalyses, we found that girls with early menarche presented consistently elevated depressive symptoms across the school year while girls with on-time menarche presented transient depressive symptoms but no differences in salivary cortisol levels. Collectively, these results show that early menarche is associated with high depressive symptoms and cortisol levels in adolescent girls. This developmental milestone may render girls more vulnerable to environmental stressors and therefore represents a critical period to intervene to promote mental health.

Age at menarche and risks of all-cause and cardiovascular death: a systematic review and meta-analysis

We conducted a systematic review and meta-analysis to investigate the associations between menarcheal age and all-cause and cardiovascular death. Medline, Embase, Scopus, and Web of Knowledge were searched for articles published prior to March 2013 reporting on the associations between menarcheal age and death from all causes or from cardiovascular disease (total cardiovascular disease, ischemic heart disease (IHD), and stroke) in adult women. Nine articles were eligible for inclusion; these reported 5 estimates each for death from all causes and total cardiovascular death, 6 estimates for IHD, and 7 estimates for death from stroke. Our meta-analysis showed that each 1-year increase in age at menarche was associated with a 3% lower relative risk of death from all causes (pooled hazard ratio = 0.97, 95% confidence interval: 0.96, 0.98) with low heterogeneity (I² = 32.2%). Meta-analysis of 2 cohorts showed a higher risk of death from all causes for women who experienced early menarche (at <12 years of age) versus “not early” menarche (at ≥12 years of age) (pooled hazard ratio = 1.23, 95% confidence interval: 1.10, 1.38; I² = 0%). An inverse association between age at menarche and death from IHD was observed only among nonsmoking populations or populations with low prevalence of smoking. We found no evidence of association between age at menarche and death from all cardiovascular diseases or stroke. Early menarche was consistently associated with higher risk of death from all causes. Further studies are needed to clarify the role of menarcheal age on cardiovascular outcomes and to investigate the potential modifying role of smoking.

A life history theory of father absence and menarche: a meta-analysis

Is the absence of biological fathers related to their daughters' earlier age at menarche? Drawing on evolutionary psychology and life history theory, prior research has suggested such a relationship (Belsky, Steinberg, and Draper, 1991; Draper and Harpending, 1982; Ellis, 2004). Although qualitative reviews have shown narrative support for this relationship (Allison and Hyde, 2013; Ellis, 2004; Kim, Smith, and Palermiti, 1997; Susman and Dorn, 2009), no quantitative review exists to provide empirical support for this relationship or to explain mixed results. Thus, we conducted a random-effects meta-analysis of correlations (Card, 2012) on father absence and daughter menarcheal age (k=33; N=70,403). The weighted mean correlation was .14, 95% CI [.09, .19], suggesting that father absence was significantly related to earlier menarche; effect sizes were heterogeneous. Egger's regression (Egger, Smith, Schneider, and Minder, 1997) showed no evidence of publication bias (file-drawer effect; r=.34, p=.052). Outcome measure differences (menarcheal age vs. menarcheal age embedded in a multi-item pubertal timing scale) did not moderate effect sizes. Study year effects (Schooler, 2011) were also non-significant. Our findings support one aspect of the life history model and provide groundwork for subsequent examination of other pathways in the model.

Role of intensive training in the growth and maturation of artistic gymnasts

Short stature and later maturation of youth artistic gymnasts are often attributed to the effects of intensive training from a young age. Given limitations of available data, inadequate specification of training, failure to consider other factors affecting growth and maturation, and failure to address epidemiological criteria for causality, it has not been possible thus far to establish cause–effect relationships between training and the growth and maturation of young artistic gymnasts. In response to this ongoing debate, the Scientific Commission of the International Gymnastics Federation (FIG) convened a committee to review the current literature and address four questions: (1) Is there a negative effect of training on attained adult stature? (2) Is there a negative effect of training on growth of body segments? (3) Does training attenuate pubertal growth and maturation, specifically, the rate of growth and/or the timing and tempo of maturation? (4) Does training negatively influence the endocrine system, specifically hormones related to growth and pubertal maturation? The basic information for the review was derived from the active involvement of committee members in research on normal variation and clinical aspects of growth and maturation, and on the growth and maturation of artistic gymnasts and other youth athletes. The committee was thus thoroughly familiar with the literature on growth and maturation in general and of gymnasts and young athletes. Relevant data were more available for females than males. Youth who persisted in the sport were a highly select sample, who tended to be shorter for chronological age but who had appropriate weight-for-height. Data for secondary sex characteristics, skeletal age and age at peak height velocity indicated later maturation, but the maturity status of gymnasts overlapped the normal range of variability observed in the general population. Gymnasts as a group demonstrated a pattern of growth and maturation similar to that observed among short-, normal-, late-maturing individuals who were not athletes. Evidence for endocrine changes in gymnasts was inadequate for inferences relative to potential training effects. Allowing for noted limitations, the following conclusions were deemed acceptable: (1) Adult height or near adult height of female and male artistic gymnasts is not compromised by intensive gymnastics training. (2) Gymnastics training does not appear to attenuate growth of upper (sitting height) or lower (legs) body segment lengths. (3) Gymnastics training does not appear to attenuate pubertal growth and maturation, neither rate of growth nor the timing and tempo of the growth spurt. (4) Available data are inadequate to address the issue of intensive gymnastics training and alterations within the endocrine system.

Developmental and contextual considerations for adrenal and gonadal hormone functioning during adolescence: Implications for adolescent mental health

Substantial research has implicated the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes independently in adolescent mental health problems, though this literature remains largely inconclusive. Given the cross-talk between the HPA and HPG axes and their increased activation in adolescence, a dual-axis approach that examines both axes simultaneously is proposed to predict the emergence and persistence of adolescent mental health problems. After briefly orienting readers to HPA and HPG axis functioning, we review the literature examining associations between hormone levels and changes with behavior during adolescence. Then, we provide a review of the literature supporting examination of both axes simultaneously and present the limited research that has taken a dual-axis approach. We propose future directions including consideration of between-person and within-person approaches to address questions of correlated changes in HPA and HPG hormones. Potential moderators are considered to increase understanding of the nuanced hormone-behavior associations during key developmental transitions.

Child maltreatment and household dysfunction: associations with pubertal development in a British birth cohort

BACKGROUND

We aimed to establish the association between adverse childhood experiences (maltreatment and household dysfunction) and pubertal maturation, which is associated with later health outcome(s).

METHODS

The 1958 British birth cohort (n = 17 638) includes all born in one week, March 1958, followed up to mid adulthood. Pubertal stage was rated by medical personnel at 11 and 16 years of age (y). Childhood maltreatment (neglect or abuse) and household dysfunction scores were constructed from information ascertained in childhood and at 45 y.

RESULTS

Childhood neglect, assessed at 7 y, was associated with late pubertal development on several markers after adjusting for early life circumstances: relative risk ratio (RRRadjusted) was 1.13 (95% CI: 1.06,1.21) and 1.06 (1.00,1.12) for late menarche and breast development (females) per unit increase in neglect score ranging 0-7, respectively; 1.14 (1.08,1.20) for late voice change and 1.07 (1.02,1.13) for pubic hair growth (males). The RRRadjusted for late pubic hair (females) and genitalia and facial hair (males) development was 1.04 (P = 0.052 to 0.085). Abuse score (0-3, for physical, sexual or psychological abuse) was associated in females with late menarche [RRRadjusted = 1.17 (1.01,1.36)] and in males with late pubic hair growth [RRRadjusted = 1.16 (1.01,1.34)] per unit increase, but not with other pubertal markers. Neither score (neglect or abuse) was associated with early puberty, but sexual abuse was associated with early [RRRadjusted = 1.86 (1.06,3.29)] as well as late menarche [RRRadjusted = 1.66 (1.02,2.71)] and witnessing abuse with early genitalia development [RRRadjusted = 1.57 (1.02,2.41)]. Household dysfunction score was not associated consistently with pubertal markers.

CONCLUSIONS

Cumulative neglect by 7 y was associated with delayed development of several pubertal markers. The underlying role of pubertal development in linking childhood neglect with future adult health warrants further consideration.

Study protocol: the Childhood to Adolescence Transition Study (CATS)

Background

Puberty is a multifaceted developmental process that begins in late-childhood with a cascade of endocrine changes that ultimately lead to sexual maturation and reproductive capability. The transition through puberty is marked by an increased risk for the onset of a range of health problems, particularly those related to the control of behaviour and emotion. Early onset puberty is associated with a greater risk of cancers of the reproductive tract and cardiovascular disease. Previous studies have had methodological limitations and have tended to view puberty as a unitary process, with little distinction between adrenarche, gonadarche and linear growth. The Childhood to Adolescence Transition Study (CATS) aims to prospectively examine associations between the timing and stage of the different hormonally-mediated changes, as well as the onset and course of common health and behavioural problems that emerge in the transition from childhood to adolescence. The initial focus of CATS is on adrenarche, the first hormonal process in the pubertal cascade, which begins for most children at around 8 years of age.

Methods/Design

CATS is a longitudinal population-based cohort study. All Grade 3 students (8–9 years of age) from a stratified cluster sample of schools in Melbourne, Australia were invited to take part. In total, 1239 students and a parent/guardian were recruited to participate in the study. Measures are repeated annually and comprise student, parent and teacher questionnaires, and student anthropometric measurements. A saliva sample was collected from students at baseline and will be repeated at later waves, with the primary purpose of measuring hormonal indices of adrenarche and gonadarche.

Discussion

CATS is uniquely placed to capture biological and phenotypic indices of the pubertal process from its earliest manifestations, together with anthropometric measures and assessment of child health and development. The cohort will provide rich detail of the development, lifestyle, external circumstances and health of children during the transition from childhood through to adolescence. Baseline associations between the hormonal measures and measures of mental health and behaviour will initially be examined cross-sectionally, and then in later waves longitudinally. CATS will make a unique contribution to the understanding of adrenarche and puberty in children’s health and development.

Breastfeeding and adolescent blood pressure: evidence from Hong Kong's "Children of 1997" Birth Cohort

Observationally, breastfeeding is associated with lower blood pressure in Western developed settings, whereas little association exists in developing settings. However, postnatal characteristics (e.g., breast milk substitutes, infection rates, underweight, and pubertal timing) differ between these settings. We examined the association of breastfeeding with blood pressure at ∼13 years, using multivariable linear regression, in 5,247 term births in 1997 from a population-representative Hong Kong Chinese birth cohort where socioeconomic patterning of breastfeeding differs from that of Western and developing settings but standard of living, social infrastructure, and postnatal characteristics are similar to those of Western settings. Higher education is associated with short-term breastfeeding but recent migration with longer-term breastfeeding. Compared with never breastfeeding, exclusive breastfeeding for ≥3 months was not associated with blood pressure (systolic mean difference = 0.82 mm Hg, 95% confidence interval (CI): -0.46, 2.11 and diastolic mean difference = 0.49 mm Hg, 95% CI: -0.22, 1.21), nor was partial breastfeeding for any length of time or exclusive breastfeeding for <3 months (systolic mean difference = 0.01 mm Hg, 95% CI: -0.64, 0.66 and diastolic mean difference = 0.16 mm Hg, 95% CI: -0.20, 0.52), adjusted for socioeconomic position and infant characteristics. Lack of association in a non-Western developed setting further suggests that observations concerning breastfeeding and blood pressure vary with setting, thereby casting doubt on causality.

The evolution of predictive adaptive responses in human life history

Many studies in humans have shown that adverse experience in early life is associated with accelerated reproductive timing, and there is comparative evidence for similar effects in other animals. There are two different classes of adaptive explanation for associations between early-life adversity and accelerated reproduction, both based on the idea of predictive adaptive responses (PARs). According to external PAR hypotheses, early-life adversity provides a 'weather forecast' of the environmental conditions into which the individual will mature, and it is adaptive for the individual to develop an appropriate phenotype for this anticipated environment. In internal PAR hypotheses, early-life adversity has a lasting negative impact on the individual's somatic state, such that her health is likely to fail more rapidly as she gets older, and there is an advantage to adjusting her reproductive schedule accordingly. We use a model of fluctuating environments to derive evolveability conditions for acceleration of reproductive timing in response to early-life adversity in a long-lived organism. For acceleration to evolve via the external PAR process, early-life cues must have a high degree of validity and the level of annual autocorrelation in the individual's environment must be almost perfect. For acceleration to evolve via the internal PAR process requires that early-life experience must determine a significant fraction of the variance in survival prospects in adulthood. The two processes are not mutually exclusive, and mechanisms for calibrating reproductive timing on the basis of early experience could evolve through a combination of the predictive value of early-life adversity for the later environment and its negative impact on somatic state.

The hypothalamic-pituitary-gonadal axis: a switch-controlled, condition-sensitive system in the regulation of life history strategies

This article is part of a Special Issue "Puberty and Adolescence". Life history theory provides an overarching framework for explaining the development of individual differences in reproductive strategies and highlights the role of familial and ecological conditions in regulating pubertal timing. Parental investment and sexual selection models afford a powerful framework for explaining the emergence of sex differences in reproductive strategies and suggest that pubertal timing in males and females is differentially sensitive to psychosocial stress. The West-Eberhard's (2003) model of switch-controlled modular systems provides the foundation for a comprehensive analysis of variation in reproductive strategies at the level of mechanism and development. Applied to puberty, this model provides a framework for explaining how genes and environments interact over development, are modulated by extant phenotypic characteristics, and operate through control of regulatory switch mechanisms across multiple levels of the hypothalamic-pituitary-gonadal axis. Taken together, life history theory, parental investment and sexual selection models, and the West-Eberhard framework enable an integrated evolutionary-developmental analysis of between-sex variation and within-sex variation in pubertal processes and their role in regulating alternative life history strategies.

Early puberty and childhood social and behavioral adjustment

PURPOSE

Early puberty has been linked to higher rates of mental health problems in adolescence. However, previous studies commencing after the initiation of puberty have been unable to explore whether early puberty is preceded by higher rates of these problems. In a large national study, we aimed to determine whether difficulties in behavior and psychosocial adjustment are evident before as well as during the early pubertal transition.

METHODS

The Longitudinal Study of Australian Children recruited a nationally representative cohort of 4,983 children at age 4-5 years in 2004. This analysis includes 3,491 of these children (70.1%) followed up at ages 6-7, 8-9, and 10-11 years, with a completed parent report of stage of pubertal maturation at age 8-9 years. Parents reported behavior difficulties (Strengths and Difficulties Questionnaire) and psychosocial adjustment (Pediatric Quality of Life Inventory) at all four waves from ages 4-5 to 10-11 years.

RESULTS

Both boys and girls who entered puberty early (i.e., by age 8-9 years) also experienced poorer psychosocial adjustment at this age. These psychosocial differences were already evident at ages 4-5 and 6-7 years, and persisted to at least age 10-11 years. Similar patterns were evident for behavior difficulties, but only for boys; early puberty was not related to behavior difficulties in girls.

CONCLUSIONS

Children with early puberty have different patterns of behavior and social adjustment from the preschool years through early adolescence. At least in part, the association between early-onset puberty and poor mental health appears to result from processes under way well before the onset of puberty.

Family adversity and autonomic reactivity association with immune changes in HIV-affected school children

OBJECTIVE

To explore whether primary school entry is associated with changes in immune system parameters in HIV-affected children. HIV-affected children are vulnerable to psychosocial stressors, regardless of their own HIV serological status.

METHODS

Data from 38 HIV-positive and 29 HIV-negative children born to seropositive women were obtained. Measures included family adversity questionnaires, autonomic nervous system (ANS) reactivity, and enumerative and functional changes in peripheral blood immune parameters.

RESULTS

In comparison with children who were HIV-negative, children who were HIV-positive at baseline had fewer CD4(+) T lymphocytes (mean [M] = 916 versus 1206 cells/mm(3) × 10(3); F = 7.8, p = .007), more CD8(+) cells (M = 1046 versus 720 cells/mm(3) × 10(3); F = 7.98, p = .006), and diminished natural killer cell cytotoxicity (M = -0.29 versus 0.41; F = 8.87, p = .004). School entry was associated with changes in immune parameters, but HIV status was not associated with the magnitude of changes. Changes in immune parameters after school entry were associated with family stress and preschool entry ANS reactivity. Highly ANS reactive children had either the greatest increase in CD8(+) cells after school entry or the greatest decrease, depending on reported levels of family adversity (B = 215.35; t = 3.74, p < .001). Changes in functional immune assays were significantly associated with the interactions between HIV status and ANS reactivity.

CONCLUSIONS

These results suggest that autonomic reactivity is associated with increased immunological sensitivity to adverse or challenging social contexts among children affected by HIV.

Puberty and adolescent sexuality

This article is part of a Special Issue "Puberty and Adolescence". Sexuality emerges as a major developmental element of puberty and the adolescent years that follow. However, connecting the sexuality that emerges with puberty and elements of adult sexuality is difficult because much adolescent sexuality research addresses the transition to partnered sexual behaviors (primarily coitus) and consequences such as unplanned pregnancy and sexually transmitted infections. This review proposes a framework of an expanded understanding of puberty and adolescent sexuality from the perspective of four hallmarks of adult sexuality: sexual desire; sexual arousal; sexual behaviors; and, sexual function. This approach thus addresses important gaps in understanding of the ontogeny of sex and the continuum of sexuality development from adolescence through the adult lifespan.

Concurrent and longitudinal associations between diurnal cortisol and body mass index across adolescence

PURPOSE

Childhood and adolescent obesity have reached epidemic levels; however, little is known about the psychobiological underpinnings of obesity in youth and whether these differ from the mechanisms identified in adults. The current study examines concurrent (i.e., measured at the same point in time) and longitudinal (i.e., using earlier cortisol measures to predict later body mass index [BMI]) associations between diurnal cortisol and BMI across adolescence.

METHODS

Adolescent diurnal cortisol was measured over 3 days at each 11, 13, and 15 years. Hierarchical linear modeling was used to extract average measures of predicted morning, afternoon, evening levels of cortisol and the diurnal slope at each assessment. Adolescent BMI (kg/m(2)) was measured at 11, 13, 15, and 18 years. Sex, family socioeconomic status, mother's BMI, pubertal status, and adolescent mental health were examined as possible confounding variables.

RESULTS

Linear regressions revealed that blunted patterns of adolescent cortisol were associated with increased measures of BMI across adolescence both concurrently and longitudinally, particularly when examining measures of cortisol in early adolescence. Multinomial logistic regressions extended the linear regression findings beyond BMI scores to encompass categories of obesity.

CONCLUSIONS

The current study builds on previous research documenting diurnal cortisol-obesity findings in adults by demonstrating similar findings exist both concurrently and longitudinally in adolescents. Findings suggest the association between cortisol and BMI is developmentally influenced and that blunted diurnal cortisol patterns can be identified in overweight individuals at a younger age than previously thought.

Identifying opportunities for cancer prevention during preadolescence and adolescence: puberty as a window of susceptibility

PURPOSE

Early life exposures during times of rapid growth and development are recognized increasingly to impact later life. Epidemiologic studies document an association between exposures at critical windows of susceptibility with outcomes as diverse as childhood and adult obesity, timing of menarche, and risk for hypertension or breast cancer.

METHODS

This article briefly reviews the concept of windows of susceptibility for providers who care for adolescent patients.

RESULTS

The theoretical bases for windows of susceptibility is examined, evaluating the relationship between pubertal change and breast cancer as a paradigm, and reviewing the underlying mechanisms, such as epigenetic modification.

CONCLUSIONS

The long-term sequela of responses to early exposures may impact other adult morbidities; addressing these exposures represents an important challenge for contemporary medicine.

Evo-devo of human adolescence: beyond disease models of early puberty

Despite substantial heritability in pubertal development, much variation remains to be explained, leaving room for the influence of environmental factors to adjust its phenotypic trajectory in the service of fitness goals. Utilizing evolutionary development biology (evo-devo), we examine adolescence as an evolutionary life-history stage in its developmental context. We show that the transition from the preceding stage of juvenility entails adaptive plasticity in response to energy resources, other environmental cues, social needs of adolescence and maturation toward youth and adulthood. Using the evolutionary theory of socialization, we show that familial psychosocial stress fosters a fast life history and reproductive strategy rather than early maturation being just a risk factor for aggression and delinquency. Here we explore implications of an evolutionary-developmental-endocrinological-anthropological framework for theory building, while illuminating new directions for research.

A systematic review of the relationships between family functioning, pubertal timing and adolescent substance use

AIMS

Experiences linked to poor family functioning and pubertal timing have each been associated with increased risk of substance misuse in adolescence. However, it remains unclear to what extent family functioning and pubertal timing combine to put adolescents at particular risk.

METHOD

A systematic review was planned, undertaken and reported according to the 27 items of the PRISMA statement. Databases World of Knowledge, PsycINFO and PubMed were searched. Fifty-eight papers were retained and are discussed in this review after screening titles, abstracts and full papers against pre-established exclusion criteria.

RESULTS

The combination of off-time pubertal timing and poor parent-adolescent relationship quality has been related to higher levels of substance use. However, this is an under-studied area of research and the evidence is less strong for boys than girls.

CONCLUSIONS

Adolescents experiencing both poor parent-adolescent relationship quality and off-time pubertal timing may represent a high-risk group that can benefit from approaches aimed at reducing risk of substance misuse.

Family relationships in childhood, pubertal timing, and subsequent reproductive strategies among adolescents

The evolutionary theory of socialization of Belsky, Steinberg, and Draper was investigated on the empirical basis of a longitudinal sample of 26 adolescent girls and boys who were born in Berlin during German reunification, as well as their mothers. Consistent with the theory, pubertal timing of the girls (but not of the boys) was predicted by the quality of parental relations in childhood, and pubertal timing of the girls (but not of the boys) was a significant predictor of the age at first intercourse. The results suggest that there are different developmental pathways for girls and boys with respect to the predictions of the evolutionary theory of socialization of Belsky et al. The findings also support the hypothesis that early onset of reproduction and frequent reproduction may be two different aspects of a quantitative reproductive strategy.

Childhood adversity and pubertal timing: understanding the origins of adulthood cardiovascular risk

OBJECTIVE

To determine whether greater childhood adversity relates to younger menarcheal age; whether younger menarcheal age relates to increased CVD risk; and whether greater childhood adversity relates to increased CVD risk, directly or indirectly (mediated by menarcheal age).

METHODS

Among 650 pre-menopausal women (ages 25-45; M=34.9[5.6]), SEM was performed to estimate relations between childhood adversity, menarcheal age, and CVD risk.

RESULTS

Results supported a covariate-adjusted model (RMSEA=0.035; CFI=0.983) in which greater childhood adversity was related to younger menarcheal age (β=-.13, p<.01) and younger menarcheal age was related to greater CVD risk (β=-.18, p<.05). Direct and indirect effects of childhood adversity on CVD risk were non-significant. Re-evaluation of the same model with additional covariate-adjustment for adulthood body composition showed the relation between menarcheal age and CVD risk attenuated (β=-.03, p=.376).

CONCLUSIONS

Cross-sectional evidence suggests family-related adversity experiences in childhood confer risk for earlier menarche which, in turn, relates to increased CVD risk in adulthood, possibly via post-pubertal body size.

Childhood abuse and age at menarche

PURPOSE

Physical and sexual abuse are prevalent social hazards. We sought to examine the association between childhood physical and sexual abuse and age at menarche.

METHODS

Among 68,505 participants enrolled in the Nurses' Health Study II, we investigated the association between childhood physical abuse and sexual abuse and menarche before age 11 years (early) or after age 15 years (late) using multivariate logistic regression analysis, mutually adjusting for both types of abuse.

RESULTS

Fifty-seven percent of respondents reported some form of physical or sexual abuse in childhood. We found a positive dose-response association between severity of sexual abuse in childhood and risk for early menarche. Compared with women who reported no childhood sexual abuse, the adjusted odds ratio (AOR) for early menarche in women who reported childhood sexual abuse was 1.20 (95% confidence interval [CI]: 1.10, 1.37) for sexual touching and 1.49 (95% CI: 1.34, 1.66) for forced sexual activity. Severe physical abuse predicted early menarche (AOR = 1.22, 95% CI: 1.10, 1.37). Childhood physical abuse had a dose-response association with late age at menarche: AOR 1.17 (95% CI: 1.04, 1.32) for mild, 1.20 (95% CI: 1.08, 1.33) for moderate, and 1.50 (95% CI: 1.27, 1.77) for severe physical abuse. Sexual abuse was not associated with late menarche.

CONCLUSIONS

Childhood abuse was prevalent in this large cohort of U.S. women. Severity of childhood sexual abuse was associated with risk for early onset of menarche, and physical abuse was associated with both early and late onset of menarche.

Life-course origins of the ages at menarche and menopause

A woman's age at menarche (first menstrual period) and her age at menopause are the alpha and omega of her reproductive years. The timing of these milestones is critical for a woman's health trajectory over her lifespan, as they are indicators of ovarian function and aging. Both early and late timing of either event are associated with risk for adverse health and psychosocial outcomes. Thus, the search for a relationship between age at menarche and menopause has consequences for chronic disease prevention and implications for public health. This article is a review of evidence from the fields of developmental biology, epidemiology, nutrition, demography, sociology, and psychology that examine the menarche-menopause connection. Trends in ages at menarche and menopause worldwide and in subpopulations are presented; however, challenges exist in constructing trends. Among 36 studies that examine the association between the two sentinel events, ten reported a significant direct association, two an inverse association, and the remainder had null findings. Multiple factors, including hormonal and environmental exposures, socioeconomic status, and stress throughout the life course are hypothesized to influence the tempo of growth, including body size and height, development, menarche, menopause, and the aging process in women. The complexity of these factors and the pathways related to their effects on each sentinel event complicate evaluation of the relationship between menarche and menopause. Limitations of past investigations are discussed, including lack of comparability of socioeconomic status indicators and biomarker use across studies, while minority group differences have received scant attention. Suggestions for future directions are proposed. As research across endocrinology, epidemiology, and the social sciences becomes more integrated, the confluence of perspectives will yield a richer understanding of the influences on the tempo of a woman's reproductive life cycle as well as accelerate progress toward more sophisticated preventive strategies for chronic disease.

Social and emotional predictors of the tempo of puberty in female rhesus monkeys

A cascade of neuroendocrine events regulates the initiation and progression of female puberty. However, the factors that determine the timing of these events across individuals are still uncertain. While the consequences of puberty on subsequent emotional development and adult behavior have received significant attention, what is less understood are the social and environmental factors that actually alter the initiation and progression of puberty. In order to more fully understand what factors influence pubertal timing in females, the present study quantified social and emotional behavior; stress physiology; and growth and activity measures in juvenile female rhesus monkeys to determine what best predicts eventual puberty. Based on previous reports, we hypothesized that increased agonistic behavior resulting from subordinate status in their natal group, in combination with slowed growth, reduced prosocial behavior, and increased emotional reactivity would predict delayed puberty. The analyses were restricted to behavioral and physiological measures obtained prior to the onset of puberty, defined as menarche. Together, our findings indicate that higher rates of aggression but lower rates of submission received from group mates; slower weight gain; and greater emotional reactivity, evidenced by higher anxiety, distress and appeasing behaviors, and lower cortisol responsivity in response to a potentially threatening situation, predicts delayed puberty. Together the combination of these variables accounted for 58% of the variance in the age of menarche, 71% in age at first ovulation, and 45% in the duration of adolescent sterility. While early puberty may be more advantageous for the individual from a fertility standpoint, it presents significant health risks, including increased risk for a number of estrogen dependent cancers and as well as the emergence of mood disorders during adulthood. On the other hand, it is possible that increased emotional reactivity associated with delayed puberty could persist, increasing the risk for emotional dysregulation to socially challenging situations. The data argue for prospective studies that will determine how emotional reactivity shown to be important for pubertal timing is affected by early social experience and temperament, and how these stress-related variables contribute to body weight accumulation, affecting the neuroendocrine regulation of puberty.

A novel quantitative approach to women's reproductive strategies

The patterned way in which individuals allocate finite resources to various components of reproduction (e.g. mating effort, reproductive timing and parental investment) is described as a reproductive strategy. As energy is limited, trade-offs between and within aspects of reproductive strategies are expected. The first aim of this study was to derive aspects of reproductive strategies using complete reproductive histories from 718 parous Western Australian women. Factor analysis using a subset of these participants resulted in six factors that represented 'short-term mating strategy', 'early onset of sexual activity', 'reproductive output', 'timing of childbearing', 'breastfeeding', and 'child spacing'. This factor structure was internally validated by replication using a second independent subset of the data. The second aim of this study examined trade-offs between aspects of reproductive strategies derived from aim one. Factor scores calculated for each woman were incorporated in generalised linear models and interaction terms were employed to examine the effect of mating behaviour on the relationships between reproductive timing, parental investment and overall reproductive success. Early sexual activity correlates with early reproductive onset for women displaying more long-term mating strategies. Women with more short-term mating strategies exhibit a trade-off between child quantity and child quality not observed in women with a long-term mating strategy. However, women with a short-term mating strategy who delay reproductive timing exhibit levels of parental investment (measured as breastfeeding duration per child) similar to that of women with long-term mating strategies. Reproductive delay has fitness costs (fewer births) for women displaying more short-term mating strategies. We provide empirical evidence that reproductive histories of contemporary women reflect aspects of reproductive strategies, and associations between these strategic elements, as predicted from life history theory.

Mathematical modeling the neuroregulation of blood pressure using a cognitive top-down approach

Background:

The body′s physiological stability is maintained by the influence of the autonomic nervous system upon the dynamic interaction of multiple systems. These physiological systems, their nature and structure, and the factors which influence their function have been poorly defined. A greater understanding of such physiological systems leads to an understanding of the synchronised function of organs in each neural network i.e. there is a fundamental relationship involving sensory input and/or sense perception, neural function and neural networks, and cellular and molecular biology. Such an approach compares with the bottom-up systems biology approach in which there may be an almost infinite degree of biochemical complexity to be taken into account.

Aims:

The purpose of this article is to discuss a novel cognitive, top-down, mathematical model of the physiological systems, in particular its application to the neuroregulation of blood pressure.

Results:

This article highlights the influence of sensori-visual input upon the function of the autonomic nervous system and the coherent function of the various organ networks i.e. the relationship which exists between visual perception and pathology.

Conclusions:

The application of Grakov′s model may lead to a greater understanding of the fundamental role played by light e.g. regulating acidity, levels of Magnesium, activation of enzymes, and the various factors which contribute to the regulation of blood pressure. It indicates that the body′s regulation of blood pressure does not reside in any one neural or visceral component but instead is a measure of the brain′s best efforts to maintain its physiological stability.

A prospective study of childhood social hardships and age at menarche

PURPOSE

To determine the role of type, timing, and cumulative childhood hardships on age at menarche in a prospective cohort study.

METHODS

A longitudinal analysis was undertaken of 4524 female participants of the National Child Development Study cohort (1958-2003). Six types of childhood hardships were identified with a factor analysis methodology. Paternal absence/low involvement in childhood was an a priori hardship. Retrospective reports of abuse in childhood also were explored in relation to age at menarche. Generalized logit regression analyses explored the impact of type, timing, and cumulative hardships on age at menarche (≤ 11, 12-13, ≥ 14 years).

RESULTS

Cumulative childhood hardships were associated with a graded increase in risk for later menarche with adjusted odds ratio [AOR] of 1.37 (95% confidence interval [95% CI], 1.10-1.70), 1.50 (95% CI, 1.18-1.91), and 1.58 (95% CI, 1.29-1.92) among those with two, three, and four or more adversities, respectively. More than two hardships in early life had the strongest association with late menarche (AOR, 2.32; 95% CI, 1.12-4.80). Sexual abuse was most strongly associated with early menarche (AOR, 2.60; 95% CI, 1.40-4.81).

CONCLUSIONS

Cumulative childhood hardships increased risk for later age at menarche. Child abuse was associated with both early and late menarche, although associations varied by type of abuse.

The Development of Human Reproductive Strategies

An evolutionary-biological perspective on the effects of the extrafamilial and familial environment on multiple psychological, behavioral, and even somatic features of children’s development challenges prevailing thinking about human development, which regards some contextual conditions and their sequelae as “good” and others as “bad.” Theory and research on the development of human reproductive strategies based on such evolutionary thinking has evolved substantially over the past two decades. In this article, I review two decades of theory and research findings pertaining to the development of reproductive strategies—highlighting the contextual regulation of pubertal timing, the distinctive role of fathers, individuals’ differential susceptibility to rearing influences, mechanisms of influence, and new ways of conceptualizing influential environmental features—and outline future directions for research.

Psychological stress and reproductive aging among pre-menopausal women

BACKGROUND

Life history models suggest that biological preparation for current versus longer term reproduction is favored in environments of adversity. In this context, we present a model of reproductive aging in which environmental adversity is proposed to increase the number of growing follicles at the cost of hastening the depletion of the ovarian reserve over time. We evaluated this model by examining psychological stress in relation to reproductive aging indexed by antral follicle count (AFC), a marker of total ovarian reserve. We hypothesized that stress would be related to (i) higher AFC in younger women, reflecting greater reproductive readiness as well as (ii) greater AFC loss across women, reflecting more accelerated reproductive aging.

METHODS

In a multi-ethnic, community sample of 979 participants [ages 25-45 (mean (standard deviation) = 35.2 (5.5)); 27.5% Caucasian] in the Ovarian Aging study, an investigation of the correlates of reproductive aging, the interaction of age-x-stress was assessed in relation to AFC to determine whether AFC and AFC loss varied across women experiencing differing levels of stress. Stress was assessed by the perceived stress scale and AFC was assessed by summing the total number of antral follicles visible by transvaginal ultrasound.

RESULTS

In linear regression examining AFC as the dependent variable, covariates (race/ethnicity, socio-economic status, menarcheal age, hormone-containing medication for birth control, parity, cigarette smoking, bodymass index, waist-to-hip ratio) and age were entered on step 1, stress on step 2 and the interaction term (age-x-stress) on step 3. On step 3, significant main effects showed that older age was related to lower AFC (b = -0.882, P = 0.000) and greater stress was related to higher AFC (b = 0.545, P = 0.005). Follow-up analyses showed that the main effect of stress on AFC was present in the younger women only. A significant interaction term (b = -0.036, P = 0.031) showed the relationship between age and AFC varied as function of stress. When the sample was divided into tertiles of stress, the average follicle loss was -0.781, -0.842 and -0.994 follicles/year in the low-, mid- and high-stress groups, respectively.

CONCLUSIONS

Psychological stress was related to higher AFC among younger women and greater AFC decline across women, suggesting that greater stress may enhance reproductive readiness in the short term at the cost of accelerating reproductive aging in the long term. Findings are preliminary, however, due to the cross-sectional nature of the current study.