Adrenarche and the evolution of human life history

Effects of social environments on male primate HPG and HPA axis developmental programming

Developmental plasticity is particularly important for humans and other primates because of our extended period of growth and maturation, during which our phenotypes adaptively respond to environmental cues. The hypothalamus-pituitary-gonadal (HPG) and hypothalamus-pituitary-adrenal (HPA) axes are likely to be principal targets of developmental "programming" given their roles in coordinating fitness-relevant aspects of the phenotype, including sexual development, adult reproductive and social strategies, and internal responses to the external environment. In social animals, including humans, the social environment is believed to be an important source of cues to which these axes may adaptively respond. The effects of early social environments on the HPA axis have been widely studied in humans, and to some extent, in other primates, but there are still major gaps in knowledge specifically relating to males. There has also been relatively little research examining the role that social environments play in developmental programming of the HPG axis or the HPA/HPG interface, and what does exist disproportionately focuses on females. These topics are likely understudied in males in part due to the difficulty of identifying developmental milestones in males relative to females and the general quiescence of the HPG axis prior to maturation. However, there are clear indicators that early life social environments matter for both sexes. In this review, we examine what is known about the impact of social environments on HPG and HPA axis programming during male development in humans and nonhuman primates, including the role that epigenetic mechanisms may play in this programming. We conclude by highlighting important next steps in this research area.

Temporal relation between pubertal development and peer victimization in a prospective sample of US adolescents

Peer victimization typically peaks in early adolescence, leading researchers to hypothesize that pubertal timing is a meaningful predictor of peer victimization. However, previous methodological approaches have limited our ability to parse out which puberty cues are associated with peer victimization because gonadal and adrenal puberty, two independent processes, have either been conflated or adrenal puberty timing has been ignored. In addition, previous research has overlooked the possibility of reverse causality-that peer victimization might drive pubertal timing, as it has been shown to do in non-human primates. To fill these gaps, we followed 265 adolescents (47% female) prospectively across three-time points (Mage : T1 = 9.6, T2 = 12.0, T3 = 14.4) and measured self-report peer victimization and self- and maternal-report of gonadal and adrenal pubertal development on the Pubertal Development Scale. Multilevel modeling revealed that females who were further along in adrenal puberty at age 9 were more likely to report peer victimization at age 12 (Cohen's d = 0.25, p = .005). The relation between gonadal puberty status and peer victimization was not significant for either sex. In terms of the reverse direction, the relation between early peer victimization and later pubertal development was not significant in either sex. Overall, our findings suggest that adrenal puberty status, but not gonadal puberty status, predicted peer victimization in females, highlighting the need to separate gonadal and adrenal pubertal processes in future studies.

Mothers' prenatal distress accelerates adrenal pubertal development in daughters

Human life history schedules vary, partly, because of adaptive, plastic responses to early-life conditions. Little is known about how prenatal conditions relate to puberty timing. We hypothesized that fetal exposure to adversity may induce an adaptive response in offspring maturational tempo. In a longitudinal study of 253 mother-child dyads followed for 15 years, we investigated if fetal exposure to maternal psychological distress related to children's adrenarche and gonadarche schedules, assessed by maternal and child report and by dehydroepiandrosterone sulfate (DHEA-S), testosterone, and estradiol levels. We found fetal exposure to elevated maternal prenatal psychological distress predicted earlier adrenarche and higher DHEA-S levels in girls, especially first-born girls, and that associations remained after covarying indices of postnatal adversity. No associations were observed for boys or for gonadarche in girls. Adrenarche orchestrates the social-behavioral transition from juvenility to adulthood; therefore, significant findings for adrenarche, but not gonadarche, suggest that prenatal maternal distress instigates an adaptive strategy in which daughters have earlier social-behavioral maturation. The stronger effect in first-borns suggests that, in adverse conditions, it is in the mother's adaptive interest for her daughter to hasten social maturation, but not necessarily sexual maturation, because it would prolong the duration of the daughter allomothering younger siblings. We postulate a novel evolutionary framework that human mothers may calibrate the timing of first-born daughters' maturation in a way that optimizes their own reproductive success.

Prenatal paternal anxiety symptoms predict child DHEA levels and internalizing symptoms during adrenarche

Introduction

This study examined (1) whether measures of paternal anxious and depressive symptoms collected prenatally and during a follow-up assessment when the child was in middle childhood, predict child neuroendocrine outcomes, and (2) whether neuroendocrine outcomes are intermediate factors between paternal mental health and child cognitive/behavioral outcomes. Middle childhood coincides with increased autonomy as the child transitions into grade school, and with adrenarche, as the maturing adrenal gland increases secretion of dehydroepiandrosterone (DHEA) and its sulfated metabolite (DHEA-S), hormones that are implicated in corticolimbic development which regulate emotions and cognition.

Methods

Participants were recruited from a subsample of a large prospective birth cohort study (3D study). We conducted a follow-up study when children were 6-8 years old (N = 61 families, 36 boys, 25 girls). Parental symptoms of anxiety, stress and depression were assessed via validated self-report questionnaires: prenatally using an in-house anxiety questionnaire, the Perceived Stress Scale (PSS) and the Center for Epidemiologic Studies Depression (CES-D), and at the follow up, using the Beck Anxiety and Beck Depression Inventories. Children provided salivary hormone samples, and their pituitary gland volume was measured from structural Magnetic Resonance Imaging (MRI) scans. Child behaviors were measured using the Strengths and Difficulties Questionnaire and cognitive outcomes using the WISC-V. Multiple regression analyses were used to test whether paternal mental health symptoms assessed prenatally and during childhood are associated with child neuroendocrine outcomes, adjusting for maternal mental health and child sex. Indirect-effect models assessed whether neuroendocrine factors are important intermediates that link paternal mental health and cognitive/behavioral outcomes.

Results

(1) Fathers' prenatal anxiety symptoms predicted lower DHEA levels in the children, but not pituitary volume. (2) Higher prenatal paternal anxiety symptoms predicted higher child internalizing symptoms via an indirect pathway of lower child DHEA. No associations were detected between paternal anxiety symptoms measured in childhood, and neuroendocrine outcomes. No child sex differences were detected on any measure.

Conclusion

These results highlight the often-overlooked role of paternal factors during pregnancy on child development, suggesting that paternal prenatal anxiety symptoms are associated with child neuroendocrine function and in turn internalizing symptoms that manifest at least up to middle childhood.

Human cytosolic steroid sulfotransferases: Versatile and rapid activity assays

Conjugation of steroids and sterol compounds with a sulfonate group is a major pathway in the regulation of their activity, synthesis and excretion. Three human cytosolic sulfotransferases are highly involved in the sulfonation of sterol compounds. SULT1E1 has a low nM affinity for estrogen sulfonation and also conjugates non-aromatic steroids with a significantly lower affinity. SULT2A1 is responsible for the high levels of fetal and adult dehydroepiandrosterone (DHEA) sulfate synthesis in the adrenal gland as well as many 3α and 3ß-hydroxysteroids and bile acids. SULT2B1b is responsible for the majority of cholesterol sulfation in tissues as well as conjugating 3ß-hydroxysteroids. Although there are multiple methods for assaying cytosolic SULT activity, two relatively simple, rapid and versatile assays for steroid sulfonation are described. The first method utilizes radiolabeled substrates and organic solvent extraction to isolate the radiolabeled product from the aqueous phase. The second assay utilizes 35S-3'-phosphoadenosine 5'-phosphosulfate (PAPS) to generate 35S-conjugated products that are resolved by thin layer chromatography. Both assays useful in situations requiring measurement of SULT activity in a timely manner.

The Sidama Model of Human Development

Human ontogeny has been shaped through evolution, resulting in markers of physical, cognitive, and social development that are widely shared and often used to demarcate the lifespan. Yet, development is demonstrably biocultural and strongly influenced by context. As a result, emic age categories can vary in duration and composition, constituted by both common physical markers as well as culturally meaningful indicators, with implications for our understanding of the evolution of human life history. Semi-structured group interviews (n = 24) among Sidama adults and children, as well as individual interviews with children (n = 30), were used to identify age categories across the lifespan and to specifically investigate acquisition of sociocultural skills and cognitive development. Ten major age categories were identified, covering birth through death. These largely map onto patterning of human universals, but specific cultural beliefs and behaviors were indicated as important markers of development. Adults and children are oriented toward the dynamic relationships between physical development and acquisition of skills tied to social and cultural success. Culture, ecology, and ontogeny are co-determinants of human development, and the interactions among them should be considered in studies examining human life history and its evolution.

DHEAS and nutritional status among Sidama, Ngandu, and Aka children: Effects of cortisol and implications for adrenarche

OBJECTIVE

Adrenarche, the biological event marked by rising production of dehydroepiandrosterone and its sulfate (DHEAS), may represent a sensitive period in child development, with important implications for adolescence and beyond. Nutritional status, particularly BMI and/or adiposity, has long been hypothesized as a factor in DHEAS production but findings are inconsistent, and few studies have examined this among non-industrialized societies. In addition, cortisol has not been included in these models. We here evaluate effects of height- (HAZ), weight- (WAZ), and BMI- (BMIZ) for-age on DHEAS concentrations among Sidama agropastoralist, Ngandu horticulturalist, and Aka hunter-gatherer children.

METHODS

Heights and weights were collected from 206 children aged 2-18 years old. HAZ, WAZ, and BMIZ were calculated using CDC standards. DHEAS and cortisol assays were used to determine biomarker concentrations in hair. Generalized linear modeling was used to examine effects of nutritional status on DHEAS concentrations, as well as cortisol, controlling for age, sex, and population.

RESULTS

Despite the prevalence of low HAZ and WAZ scores, the majority (77%) of children had BMI z-scores >-2.0 SD. Nutritional status has no significant effect on DHEAS concentrations, controlling for age, sex, and population. Cortisol, however, is a significant predictor of DHEAS concentrations.

CONCLUSIONS

Our findings do not support a relationship between nutritional status and DHEAS. Instead, results suggest an important role for stress and ecology in DHEAS concentrations across childhood. Specifically, effects of environment via cortisol may be influential to patterning of DHEAS. Future work should investigate local ecological stressors and their relationship to adrenarche.

Impacts of adrenarcheal DHEA levels on spontaneous cortical activity during development

Dehydroepiandrosterone (DHEA) production is closely associated with the first pubertal hormonal event, adrenarche. Few studies have documented the relationships between DHEA and functional brain development, with even fewer examining the associations between DHEA and spontaneous cortical activity during the resting-state. Thus, whether DHEA levels are associated with the known developmental shifts in the brain's idling cortical rhythms remains poorly understood. Herein, we examined spontaneous cortical activity in 71 typically-developing youth (9-16 years; 32 male) using magnetoencephalography (MEG). MEG data were source imaged and the power within five canonical frequency bands (delta, theta, alpha, beta, gamma) was computed to identify spatially- and spectrally-specific effects of salivary DHEA and DHEA-by-sex interactions using vertex-wise ANCOVAs. Our results indicated robust increases in power with increasing DHEA within parieto-occipital cortices in all frequency bands except alpha, which decreased with increasing DHEA. In the delta band, DHEA and sex interacted within frontal and temporal cortices such that with increasing DHEA, males exhibited increasing power while females showed decreasing power. These data suggest that spontaneous cortical activity changes with endogenous DHEA levels during the transition from childhood to adolescence, particularly in sensory and attentional processing regions. Sexually-divergent trajectories were only observed in later-developing frontal cortical areas.

The impact of pubertal DHEA on the development of visuospatial oscillatory dynamics

The adolescent brain undergoes tremendous structural and functional changes throughout puberty. Previous research has demonstrated that pubertal hormones can modulate sexually dimorphic changes in cortical development, as well as age-related maturation of the neural activity underlying cognitive processes. However, the precise impact of pubertal hormones on these functional changes in the developing human brain remains poorly understood. In the current study, we quantified the neural oscillatory activity serving visuospatial processing using magnetoencephalography, and utilized measures of dehydroepiandrosterone (DHEA) as an index of development during the transition from childhood to adolescence (i.e., puberty). Within a sample of typically developing youth (ages 9-15), a novel association between pubertal DHEA and theta oscillatory activity indicated that less mature children exhibited stronger neural responses in higher-order prefrontal cortices during the visuospatial task. Theta coherence between bilateral prefrontal regions also increased with increasing DHEA, such that network-level theta activity became more distributed with more maturity. Additionally, significant DHEA-by-sex interactions in the gamma range were centered on cortical regions relevant for attention processing. These findings suggest that pubertal DHEA may modulate the development of neural oscillatory activity serving visuospatial processing and attention functions during the pubertal period.

Evidence for an adolescent sensitive period to family experiences influencing adult male testosterone production

SignificanceTestosterone influences how animals devote energy and time toward reproduction, including opposing demands of mating and competition versus parenting. Reflecting this, testosterone often declines in new fathers and lower testosterone is linked to greater caregiving. Given these roles, there is strong interest in factors that affect testosterone, including early-life experiences. In this multidecade study, Filipino sons whose fathers were present and involved with raising them when they were adolescents had lower testosterone when they later became fathers, compared to sons whose fathers were present but uninvolved or were not coresident. Sons' own parenting behaviors did not explain these patterns. These results connect key social experiences during adolescence to adult testosterone, and point to possible intergenerational effects of parenting style.

Body mass index rebound and pubertal timing in girls with and without a family history of breast cancer: the LEGACY girls study

BACKGROUND

Heavier body mass index (BMI) is the most established predictor of earlier age at puberty. However, it is unknown whether the timing of the childhood switch to heavier BMI (age at BMI rebound) also matters for puberty.

METHODS

In the LEGACY Girls Study (n = 1040), a longitudinal cohort enriched with girls with a family history of breast cancer, we collected paediatric growth chart data from 852 girls and assessed pubertal development every 6 months. Using constrained splines, we interpolated individual growth curves and then predicted BMI at ages 2, 4, 6, 8 and 9 years for 591 girls. We defined age at BMI rebound as the age at the lowest BMI between ages 2 and 8 years and assessed its association with onset of thelarche, pubarche and menarche using Weibull survival models.

RESULTS

The median age at BMI rebound was 5.3 years (interquartile range: 3.6-6.7 years). A 1-year increase in age at BMI rebound was associated with delayed thelarche (HR = 0.90; 95% CI = 0.83-0.97) and menarche (HR = 0.86; 95% CI = 0.79-0.94). The magnitude of these associations remained after adjusting for weight between birth and 2 years, was stronger after adjusting for BMI at age 9, and was stronger in a subset of girls with clinically assessed breast development.

CONCLUSIONS

Earlier BMI rebound is associated with earlier pubertal timing. Our observation that BMI rebound may be a driver of pubertal timing in girls with and without a family history of breast cancer provides insight into how growth and pubertal timing are associated with breast cancer risk.

Sex-specific differences in somatic investment and strategies of physical activity among Portuguese schoolchildren

OBJECTIVES

Physical activity (PA) is required for healthy growth, development, and maturation and plays an important role in the prevention of overweight and obesity in childhood and adolescence. Sex-differences in PA levels are well documented, with boys spending more time in PA, especially in moderate-to-vigorous activities. Following the Life History Theory, our aim is to study if PA affects the fat tissues increases during childhood and juvenile phases in both sexes.

METHODS

Time spent in sedentary, light, and moderate-to-vigorous PA levels were measured in a sample of 415 Portuguese children and juveniles (207 females/208 males; aged 6-11 years), using an accelerometer for 7 days. Skinfolds related with body fat were objectively collected and socioeconomic status factors were reported using a parental questionnaire.

RESULTS

The outcomes show that girls' and boys' fat variables increased during the end of the childhood and the juvenile phase. However, these variables were differently affected by PA. Girls increased fat variables with the sedentary activity while boys decreased fat variables with moderate-to-vigorous PA. Alike, active boys but not girls reduced the fat increase tendency with age.

CONCLUSIONS

Although both sexes displayed a general fat increment with age, moderate-to-vigorous PA dampens the increase only in boys. In fact, active girls increased body fat in the same manner as non-active girls. From an evolutionary perspective, it could explain sex-specific somatic strategies related to future reproduction or, with future mating and intrasexual competition.

Pubertal development mediates the association between family environment and brain structure and function in childhood

Psychosocial acceleration theory suggests that pubertal maturation is accelerated in response to adversity. In addition, suboptimal caregiving accelerates development of the amygdala–medial prefrontal cortex circuit. These findings may be related. Here, we assess whether associations between family environment and measures of the amygdala–medial prefrontal cortex circuit are mediated by pubertal development in more than 2000 9- and 10-year-old children from the Adolescent Brain Cognitive Development Study (http://dx.doi.org/10.15154/1412097). Using structural equation modeling, demographic, child-reported, and parent-reported data on family dynamics were compiled into a higher level family environment latent variable. Magnetic resonance imaging preprocessing and compilations were performed by the Adolescent Brain Cognitive Development Study's data analysis core. Anterior cingulate cortex (ACC) thickness, area, white matter fractional anisotropy, amygdala volume, and cingulo-opercular network–amygdala resting-state functional connectivity were assessed. For ACC cortical thickness and ACC fractional anisotropy, significant indirect effects indicated that a stressful family environment relates to more advanced pubertal stage and more mature brain structure. For cingulo-opercular network–amygdala functional connectivity, results indicated a trend in the expected direction. For ACC area, evidence for quadratic mediation by pubertal stage was found. Sex-stratified analyses suggest stronger results for girls. Despite small effect sizes, structural measures of circuits important for emotional behavior are associated with family environment and show initial evidence of accelerated pubertal development.

Beyond Glucocorticoids: Integrating Dehydroepiandrosterone (DHEA) into Animal Welfare Research

Animal welfare researchers are committed to identifying novel measures for enhancing the quality of life of individual animals. Recently, welfare scientists have emphasized the need for tracking multiple indicators of an animal's behavioral, emotional and mental health. Researchers are currently focused on integrating non-invasive physiological biomarkers to gain insight into an individual's welfare status. Most commonly, the animal welfare community has analyzed glucocorticoid hormones and their metabolites as a measure of stress. While glucocorticoids provide valuable information about hypothalamic-pituitary-adrenal (HPA) axis activity, there are limitations to utilizing these hormones as the sole measure of long-term stress and welfare. Other biomarkers, such as dehydroepiandrosterone and its sulfate ester-collectively referred to as DHEA(S)-help provide a more complete picture of HPA activity. DHEA(S) counteracts the effects glucocorticoids by having anti-aging, immune-enhancing and neuroprotective properties. Recent studies have examined the ratio of glucocorticoids to DHEA(S) as a way to better understand how the HPA axis is functioning. There is evidence that this ratio serves as an indicator of immune function, mental health, cognitive performance and overall welfare. We review studies that employed the glucocorticoid:DHEA(S) ratio, outline methodological considerations and discuss how researchers can integrate glucocorticoids, DHEA(S) and the glucocorticoid:DHEA(S) ratio into welfare assessments.

"I'm not a freshi": Culture shock, puberty and growing up as British-Bangladeshi girls

Early puberty is a risk factor for adult diseases and biomedical and psychosocial research implicate growth (in height and weight) and stress as modifiable drivers of early puberty. Seldom have studies examined these drivers simultaneously or concurrently using quantitative and qualitative methods. Within the context of migration, we used mixed-methods to compare growth, stress and puberty in a study of 488 girls, aged 5–16, who were either Bangladeshi, first-generation migrant to the UK, second-generation migrant, or white British (conducted between 2009 and 2011). Using a biocultural framework, we asked the questions: 1) Does migration accelerate pubertal processes? 2) What biocultural markers are associated with migration? 3) What biocultural markers are associated with puberty? Girls self-reported pubertal stage, recalled 24-h dietary intake, and answered questions relating to dress, food, and ethnic identity. We collected anthropometrics and assayed saliva specimens for dehydroepiandrosterone-sulfate (DHEA-S) to assess adrenarcheal status. Our findings demonstrate that first-generation migrants had earlier puberty than second-generation migrants and Bangladeshi girls. British style of dress did not increase with migration, while dietary choices did, which were reflected in increasing body mass index. However, the widely-used phrase, “I'm proud of my religion, but not my culture” demonstrated that ethnic identity was aligned more with Islamic religion than ‘Bangladeshi culture.’ This was epitomized by wearing the hijab, but denial of eating rice. The social correlates of puberty, such as ‘practicing’ wearing the hijab and becoming ‘dedicated to the scarf,’ occurred at the same ages as adrenarche and menarche, respectively, among first-generation girls. We suggest that the rejection of ‘Bangladeshi culture’ might be a source of psychosocial stress for first-generation girls, and this may explain elevated DHEA-S levels and early puberty compared to their second-generation counterparts. Our results support a biocultural model of adolescence, a period for biological embedding of culture, when biological and psychosocial factors adjust developmental timing with potential positive and negative implications for long-term health.

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Compares puberty in migrant Bangladeshi girls in the UK using mixed-methods.

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Argues that stigma may explain early maturation in first-generation migrants.

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Reveals overlapping ages of biological and cultural puberty in migrant girls.

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Generates new biocultural hypotheses via hormonal, growth and social stigma data.

Hormones and human developmental plasticity

Natural selection favors the evolution of mechanisms that optimize the allocation of resources and time among competing traits. Hormones mediate developmental plasticity, the changes in the phenotype that occur during ontogeny. Despite their highly conserved functions, the flexibilities of human hormonal systems suggest a strong history of adaptation to variable environments. Physiological research on developmental plasticity has focused on the early programming effects of stress, the hypothalamus-pituitary-adrenal axis (HPAA) and the hypothalamus-pituitary-gonadal axis (HPGA) during critical periods, when the hormones produced have the strongest influence on the developing brain. Often this research emphasizes the maladaptive effects of early stressful experiences. Here we posit that the HPAA and HPAG systems in human developmental plasticity have evolved to be responsive to complex and dynamic problems associated with human sociality. The lengthy period of human offspring dependency, and its associated brain development and risks, is linked to the uniquely human combination of stable breeding bonds, extensive paternal effort in a multi-male group, extended bilateral kin recognition, grandparenting, and controlled exchange of mates among kin groups. We evaluate an evolutionary framework that integrates proximate physiological explanations with ontogeny, phylogeny, adaptive function, and comparative life history data.

A lex naturalis delineates components of a human-specific, adrenal androgen-dependent, p53-mediated 'kill switch' tumor suppression mechanism

We have recently described in this journal our detection of an anthropoid primate-specific, adrenal androgen-dependent, p53-mediated, 'kill switch' tumor suppression mechanism that reached its fullest expression only in humans, as a result of human-specific exposure to polycyclic aromatic hydrocarbons caused by the harnessing of fire - but which has components reaching all the way back to the origin of the primate lineage. We proposed that species-specific mechanisms of tumor suppression are a generalized requirement for vertebrate species to increase in body size or lifespan beyond those of species basal to their lineage or to exploit environmental niches which increase exposure to carcinogenic substances. Using empirical dynamic modeling, we have also reported our detection of a relationship between body size, lifespan, and species-specific mechanism of tumor suppression (and here add carcinogen exposure), such that a change in any one of these variables requires an equilibrating change in one or more of the others in order to maintain lifetime cancer risk at a value of about 4%, as observed in virtually all larger, longer-lived species under natural conditions. Here we show how this relationship, which we refer to as the lex naturalis of vertebrate speciation, elucidates the evolutionary steps underlying an adrenal androgen-dependent, human-specific 'kill switch' tumor suppression mechanism; and further, how it prescribes a solution to 'normalize' lifetime cancer risk in our species from its current aberrant 40% to the 4% that characterized primitive humans. We further argue that this prescription writ by the lex naturalis represents the only tenable strategy for meaningful suppression of the accelerating impact of cancer upon our species.

Emerging Adulthood, a Pre-adult Life-History Stage

The duration of human maturation has been underestimated; an additional 4-6-year pre-adult period of "emerging adulthood," should be included in models of human maturation. It is a period of brain maturation, learning about intimacy and mutual support, intensification of pre-existing friendships, family-oriented socialization, and the attainment of those social skills that are needed for mating and reproduction. We propose that emerging adulthood is a life-history stage that is a foundation of the high reproductive success of human beings. The period of emerging adulthood has an evolutionary context and developmental markers, and we present evidence that supports the idea that emerging adults require protection because they are still learning and maturing.

DHEAS and Human Development: An Evolutionary Perspective

Adrenarche, the post-natal rise of DHEA and DHEAS, is unique to humans and the African Apes. Recent findings have linked DHEA in humans to the development of the left dorsolateral prefrontal cortex (LDPFC) between the ages of 4-8 years and the right temporoparietal junction (rTPJ) from 7 to 12 years of age. Given the association of the LDLPFC with the 5-to-8 transition and the rTPJ with mentalizing during middle childhood DHEA may have played an important role in the evolution of the human brain. I argue that increasing protein in the diet over the course of human evolution not only increased levels of DHEAS, but linked meat consumption with brain development during the important 5- to-8 transition. Consumption of animal protein has been associated with IGF-1, implicated in the development of the adrenal zona reticularis (ZR), the site of DHEAS production. In humans and chimps, the zona reticularis emerges at 3-4 years, along with the onset of DHEA/S production. For chimps this coincides with weaning and peak synaptogenesis. Among humans, weaning is completed around 2 ½ years, while synaptogenesis peaks around 5 years. Thus, in chimpanzees, early cortical maturation is tied to the mother; in humans it may be associated with post-weaning provisioning by others. I call for further research on adrenarche among the African apes as a critical comparison to humans. I also suggest research in subsistence populations to establish the role of nutrition and energetics in the timing of adrenarche and the onset of middle childhood.

Human-like adrenal development in wild chimpanzees: A longitudinal study of urinary dehydroepiandrosterone-sulfate and cortisol

The development of the adrenal cortex varies considerably across primates, being most conspicuous in humans, where a functional zona reticularis-the site of dehydroepiandrosterone-sulfate (DHEA/S) production-does not develop until middle childhood (5-8 years). Prior reports suggest that a human-like adrenarche, associated with a sharp prepubertal increase in DHEA/S, may only occur in the genus Pan. However, the timing and variability in adrenarche in chimpanzees remain poorly described, owing to the lack of longitudinal data, or data from wild populations. Here, we use urine samples from East African chimpanzees (Pan troglodytes schweinfurthii) collected over 20 years at Kanyawara in Kibale National Park, Uganda, to trace the developmental trajectories of DHEAS (n = 1,385 samples, 53 individuals) and cortisol (n = 12,726 samples, 68 individuals). We used generalized additive models (GAM) to investigate the relationship between age, sex, and hormone levels. Adrenarche began earlier in chimpanzees (~2-3 years) compared with what has been reported in humans (6-8 years) and, unlike humans, male and female chimpanzees did not differ significantly in the timing of adrenarche nor in DHEAS concentrations overall. Similar to what has been reported in humans, cortisol production decreased through early life, reaching a nadir around puberty (8-11 years), and a sex difference emerged with males exhibiting higher urinary cortisol levels compared with females by early adulthood (15-16 years). Our study establishes that wild chimpanzees exhibit a human-like pattern of cortisol production during development and corroborates prior reports from captive chimpanzees of a human-like adrenarche, accompanied by significant developmental increases in DHEAS. While the role of these developmental hormone shifts are as yet unclear, they have been implicated in stages of rapid behavioral development once thought unique to humans, especially in regard to explaining the divergence of female and male social behavior before pubertal increases in gonadal hormones.

Pubertal development mediates the association between family environment and brain structure and function in childhood

Psychosocial acceleration theory suggests that pubertal maturation is accelerated in response to adversity. In addition, suboptimal caregiving accelerates development of the amygdala-medial prefrontal cortex circuit. These findings may be related. Here, we assess whether associations between family environment and measures of the amygdala-medial prefrontal cortex circuit are mediated by pubertal development in more than 2000 9- and 10-year-old children from the Adolescent Brain Cognitive Development Study (http://dx.doi.org/10.15154/1412097). Using structural equation modeling, demographic, child-reported, and parent-reported data on family dynamics were compiled into a higher level family environment latent variable. Magnetic resonance imaging preprocessing and compilations were performed by the Adolescent Brain Cognitive Development Study's data analysis core. Anterior cingulate cortex (ACC) thickness, area, white matter fractional anisotropy, amygdala volume, and cingulo-opercular network-amygdala resting-state functional connectivity were assessed. For ACC cortical thickness and ACC fractional anisotropy, significant indirect effects indicated that a stressful family environment relates to more advanced pubertal stage and more mature brain structure. For cingulo-opercular network-amygdala functional connectivity, results indicated a trend in the expected direction. For ACC area, evidence for quadratic mediation by pubertal stage was found. Sex-stratified analyses suggest stronger results for girls. Despite small effect sizes, structural measures of circuits important for emotional behavior are associated with family environment and show initial evidence of accelerated pubertal development.

In utero and postnatal programing of dehydroepiandrosterone sulfate (DHEAS) in young adult women

Fetal adrenal-derived OH-DHEAS is the primary precursor for maternal estriol, an abundant, human, placental estrogen. We measured maternal pregnancy estriol as a marker of fetal adrenal function + placenta capacity to synthesize estriol. We hypothesized that maternal estriol is directly correlated with the adrenal hormone, DHEAS, in young adult women. We tested this hypothesis in a subset of women in the Child Health and Development Studies (351 of 470 eligible). 176 of these had serum samples collected at ages 27-30 for DHEAS assays, archived maternal pregnancy serum for estriol assays, and childhood growth data. In regression analyses, both maternal estriol and accelerated growth in middle childhood were independently, directly associated with DHEAS (+19% for quartile 4 versus quartile 1 of estriol, 95%CI=+ 2%, +36% and +12% for quartile 4 versus quartile 1 for middle childhood growth, 95%CI= +3%, +21%). Adrenal function may be programmed in utero and middle childhood with long-term consequences.

A tale of two steroids: The importance of the androgens DHEA and DHEAS for early neurodevelopment

DHEA and DHEAS are neuroactive neurosteroids that interact with several major receptor systems in the brain, including sigma (σ), glutamate, and GABA-A receptors. It has been recognized as early as 1952, that the loss of DHEA/DHEAS in adult life is associated with neuropsychiatric disorders (eg schizophrenia, depression). However, the mechanistic role for DHEA/DHEAS in any of these domains remains speculative, not the least because the presence of these androgens in the adrenal gland and brain is largely confined to humans and only some non-human primates. DHEA and DHEAS are dynamically regulated from before birth and before the onset of puberty, and therefore an understanding of the synthesis, regulation, and functions of this important androgen pathway warrants attention. Here, we draw attention to the possible modulating influence of DHEA/DHEAS in early brain development from fetal life to the remarkable increase of these steroids in early childhood - the adrenarche. We propose that the pre-pubertal DHEA/DHEAS surge plays a key role in modulating early brain development, perhaps by prolonging brain plasticity during childhood to allow the pre-adolescent brain to adapt and re-wire in response to new, and ever-changing social challenges. Nonetheless, the aetiology of neurodevelopmental phenomena in relation to DHEA/DHEAS synthesis and action cannot be easily studied in humans due to the obvious ethical restrictions on mechanistic studies, the uncertainty of predicting the future mental characteristics of individuals, and the difficulty of conducting retrospective investigations based on pre-birth and/or neonatal complications. We discuss new opportunities for animal studies to resolve these important questions.

Conceptualizing Puberty as a Window of Opportunity for Impacting Health and Well-Being Across the Life Span

We promote the perspective that puberty, a separate biological process embedded in adolescence, is a "window of opportunity" for understanding and impacting health and development. First, we include a brief overview of pubertal change. Second, we propose a critical role for puberty in shaping life span health due to its connections with early life precursors, health issues and risks emerging during puberty, and health in young adulthood and beyond. Next, we discuss the importance of puberty measures in developmental research and suggest ways to make the science of puberty an important standalone research entity, as well as an essential component of studies conducted during adolescence. Finally, we discuss measurement issues, novel theoretical models of puberty, and the necessity of adopting an interdisciplinary perspective in research on puberty and in adolescence more broadly.

Increased symptoms of anxiety and depression in prepubertal girls, but not boys, with premature adrenarche: associations with serum DHEAS and daily salivary cortisol concentrations

Concerns over anxiety and depressive symptoms in children with premature adrenarche (PA) have been recently raised. However, to date, most relevant studies are on a small number of girls. In this cross-sectional study, 82 pre-pubertal children (66 girls and 16 boys) diagnosed with PA, were compared to 63 control children regarding their psychological characteristics and hypothalamic-pituitary-adrenal (HPA) axis function, as assessed by salivary cortisol measurement. Symptoms of anxiety and depression were assessed by child self-report (Spence Children's Anxiety Scale (SCAS) and Depression self-rating scale for Children (DSRS)) and parent-report (Child Behaviour Checklist (CBCL)) tests validated for the Greek population. Salivary cortisol levels were determined directly after awakening (approximately 7am) and evening (8pm) of the same day. Morning serum DHEAS levels were assessed in PA children. Girls with PA scored significantly higher on anxiety (p = .016) and depression (p =.039) scales than controls. No group differences were noted for parent reports and children's salivary cortisol concentrations. Boys with PA did not demonstrate significant differences in any of the aforementioned parameters. Our findings suggest that girls with PA may be at higher risk for reporting symptoms of anxiety and depression than their non-PA peers. HPA axis dysregulation in this population was not documented.

Hunter-gatherer diets and human behavioral evolution

Human behavior and physiology evolved under conditions vastly different from those which most humans inhabit today. This paper summarizes long-term dietary studies conducted on contemporary hunter-gatherer populations (sometimes referred to as foragers). Selected studies for the most part that use evolutionary theoretical perspectives and data collection methods derived from the academic field of human behavioral ecology, which derives relatively recently from the fields of evolutionary biology, ethology, population biology and ecological anthropology. I demonstrate how this body of research illuminates ancestral patterns of food production, consumption and sharing, infant feeding, and juvenile subsistence contributions in hunter-gatherer economies. Insights from hunter-gatherer studies are then briefly discussed within the context of better-studied human populations that are Westernized, Educated, Industrialized, Rich, and Democratic (WEIRD).

Hormones and Human and Nonhuman Primate Growth

The aim of this paper was to review information pertaining to the hormonal regulation of nonhuman primate growth, with specific focus on the growth hormone (GH)-insulin-like growth factor (IGF) axis and adrenal androgens. Hormones of the GH-IGF axis are consistently associated with measures of growth - linear, weight, or both - during the growth period; in adulthood, concentrations of IGF-I, IGF-binding protein-3, and GH-binding protein are not associated with any measures of size. Comparing patterns of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) may be especially relevant for understanding whether the childhood stage of growth and development is unique to humans and perhaps other apes. Genetic, hormonal, and morphological data on adrenarche in other nonhuman primate species suggest that this endocrine transition is delayed in humans, chimpanzees, and possibly gorillas, while present very early in postnatal life in macaques. This suggests that although perhaps permitted by an extension of the pre-adolescent growth period, childhood builds upon existing developmental substrates rather than having been inserted de novo into an ancestral growth trajectory. Hormones can provide insight regarding the evolution of the human growth trajectory.

DHEA in Prenatal and Postnatal Life: Implications for Brain and Behavior

Dehydroepiandrosterone (DHEA) and its sulfated congener (DHEAS) are the principal C₁₉ steroid produced by the adrenal gland in many mammals, including humans. It is secreted in high concentrations during fetal life, but synthesis decreases after birth until, in humans and some other primates, there is a prepubertal surge of DHEA production by the adrenal gland-a phenomenon known as adrenarche. There remains considerable uncertainty about the physiological role of DHEA and DHEAS. Moreover, the origin of the trophic drives that determine the waxing and waning of DHEA synthesis are poorly understood. These gaps in knowledge arise in some measure from the difficulty of understanding mechanistic determinants from observations made opportunistically in humans and primates, and have stimulated a search for other suitable species that exhibit adrenarche- and adrenopause-like changes of adrenal function. DHEA and DHEAS are clearly neuroactive steroids with actions at several neurotransmitter receptors; indeed, DHEA is now known to be also synthesized by many parts of the brain, and this capacity undergoes ontogenic changes, but whether this is dependent or independent of the changes in adrenal synthesis is unknown. In this chapter we review key contributions to this field over the last 50+ years, and speculate on the importance of DHEA for the brain, both during development and for maturation and aging of cerebral function and behavior.

Individual differences in developmental plasticity: A role for early androgens?

Developmental plasticity is a widespread property of living organisms, but different individuals in the same species can vary greatly in how susceptible they are to environmental influences. In humans, research has sought to link variation in plasticity to physiological traits such as stress reactivity, exposure to prenatal stress-related hormones such as cortisol, and specific genes involved in major neurobiological pathways. However, the determinants of individual differences in plasticity are still poorly understood. Here we present the novel hypothesis that, in both sexes, higher exposure to androgens during prenatal and early postnatal life should lead to increased plasticity in traits that display greater male variability (i.e., a majority of physical and behavioral traits). First, we review evidence of greater phenotypic variation and higher susceptibility to environmental factors in males; we then consider evolutionary models that explain greater male variability and plasticity as a result of sexual selection. These empirical and theoretical strands converge on the hypothesis that androgens may promote developmental plasticity, at least for traits that show greater male variability. We discuss a number of potential mechanisms that may mediate this effect (including upregulation of neural plasticity), and address the question of whether androgen-induced plasticity is likely to be adaptive or maladaptive. We conclude by offering suggestions for future studies in this area, and considering some research designs that could be used to empirically test our hypothesis.

The tempo of human childhood: a maternal foot on the accelerator, a paternal foot on the brake

Relative to the life history of other great apes, that of humans is characterized by early weaning and short interbirth intervals (IBIs). We propose that in modern humans, birth until adrenarche, or the rise in adrenal androgens, developmentally corresponds to the period from birth until weaning in great apes and ancestral hominins. According to this hypothesis, humans achieved short IBIs by subdividing ancestral infancy into a nurseling phase, during which offspring fed at the breast, and a weanling phase, during which offspring fed specially prepared foods. Imprinted genes influence the timing of human weaning and adrenarche, with paternally expressed genes promoting delays in childhood maturation and maternally expressed genes promoting accelerated maturation. These observations suggest that the tempo of human development has been shaped by consequences for the fitness of kin, with faster development increasing maternal fitness at a cost to child fitness. The effects of imprinted genes suggest that the duration of the juvenile period (adrenarche until puberty) has also been shaped by evolutionary conflicts within the family.

Dehydroepiandrosterone and Dehydroepiandrosterone-Sulfate and Emotional Processing

Steroid hormones are important regulators of brain development, physiological function, and behavior. Among them, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulfate (DHEAS) also do modulate emotional processing and may have mood enhancement effects. This chapter reviews the studies that bear relation to DHEA and DHEAS [DHEA(S)] and brain emotional processing and behavior. A brief introduction to the mechanisms of action and variations of DHEA(S) levels throughout life has also been forward in this chapter. Higher DHEA(S) levels may reduce activity in brain regions involved in the generation of negative emotions and modulate activity in regions involved in regulatory processes. At the electrophysiological level, higher DHEA-to-cortisol and DHEAS-to-DHEA ratios were related to shorter P300 latencies and shorter P300 amplitudes during the processing of negative stimuli, suggesting less interference of negative stimuli with the task and less processing of the negative information, which in turn may suggest a protective mechanism against negative information overload. Present knowledge indicates that DHEA(S) may play a role in cortical development and plasticity, protecting against negative affect and depression, and at the same time enhancing attention and overall working memory, possibly at the cost of a reduction in emotional processing, emotional memory, and social understanding.

DHEAS patterning across childhood in three sub-Saharan populations: Associations with age, sex, ethnicity, and cortisol

OBJECTIVES

Hormones have many roles in human ontogeny, including the timing of life history 'switch points' across development. Limited hormonal data exist from non-Western children, leaving a significant gap in our understanding of the diversity of life history patterning. This cross-sectional study examines dehydroepiandrosterone sulfate (DHEAS) production in relation to age, sex, ethnicity, and cortisol concentrations, as well as average age of adrenarche, among Aka and Ngandu children of the Central African Republic and Sidama children of Ethiopia.

METHODS

Hair was collected from 480 children (160 per population) aged 3-18 years old. These samples were analyzed for DHEAS and cortisol concentrations using ELISAs. A generalized additive model was used to examine DHEAS patterning in relation to age, sex, cortisol, and ethnicity. The derivative of DHEAS as a function of age was used to identify average age of adrenarche in each population.

RESULTS

DHEAS patterning in these three populations is distinct from Euro-American patterns of production. In all three groups, the population-level age at adrenarche onset occurs slightly later than Euro-American averages, with both Central African populations experiencing a later onset than the Ethiopian population.

CONCLUSIONS

DHEAS patterns and age at adrenarche vary across cultures, perhaps indicating adaptive life history responses in diverse eco-cultural environments. Delayed involution of the fetal zone and DHEAS patterning may offer both cognitive protection and immune defense in high-risk, nutritionally-poor environments. Additional research in the majority world is essential to improving our understanding of the diversity of hormonal development and timing of 'switch points' in life history trajectories.

Uptake and metabolism of sulphated steroids by the blood-brain barrier in the adult male rat

Little is known about the origin of the neuroactive steroids dehydroepiandrosterone sulphate (DHEAS) and pregnenolone sulphate (PregS) in the brain or of their subsequent metabolism. Using rat brain perfusion in situ, we have found ³H‐PregS to enter more rapidly than ³H‐DHEAS and both to undergo extensive (> 50%) desulphation within 0.5 min of uptake. Enzyme activity for the steroid sulphatase catalysing this deconjugation was enriched in the capillary fraction of the blood–brain barrier and its mRNA expressed in cultures of rat brain endothelial cells and astrocytes. Although permeability measurements suggested a net efflux, addition of the efflux inhibitors GF120918 and/or MK571 to the perfusate reduced rather than enhanced the uptake of ³H‐DHEAS and ³H‐PregS; a further reduction was seen upon the addition of unlabelled steroid sulphate, suggesting a saturable uptake transporter. Analysis of brain fractions after 0.5 min perfusion with the ³H‐steroid sulphates showed no further metabolism of PregS beyond the liberation of free steroid pregnenolone. By contrast, DHEAS underwent 17‐hydroxylation to form androstenediol in both the steroid sulphate and the free steroid fractions, with some additional formation of androstenedione in the latter. Our results indicate a gain of free steroid from circulating steroid sulphates as hormone precursors at the blood–brain barrier, with implications for ageing, neurogenesis, neuronal survival, learning and memory.

A review of human male field studies of hormones and behavioral reproductive effort

The purpose of this paper is to review field studies of human male hormones and reproductive behavior. We first discuss life history theory and related conceptual considerations. As illustrations, distinctive features of human male life histories such as coalitional aggression, long-term partnering and paternal care are noted, along with their relevance to overall reproductive effort and developmental plasticity. We address broad questions about what constitutes a human male field study of hormones and behavior, including the kinds of hormone and behavioral measures employed in existing studies. Turning to several sections of empirical review, we present and discuss evidence for links between prenatal and juvenile androgens and sexual attraction and aggression. This includes the proposal that adrenal androgens-DHEA and androstenedione-may play functional roles during juvenility as part of a life-stage specific system. We next review studies of adult male testosterone responses to competition, with these studies emphasizing men's involvement in individual and team sports. These studies show that men's testosterone responses differ with respect to variables such as playing home/away, winning/losing, and motivation. Field studies of human male hormones and sexual behavior also focus on testosterone, showing some evidence of patterned changes in men's testosterone to sexual activity. Moreover, life stage-specific changes in male androgens may structure age-related differences in sexual behavior, including decreases in sexual behavior with senescence. We overview the considerable body of research on male testosterone, partnerships and paternal care, noting the variation in social context and refinements in research design. A few field studies provide insight into relationships between partnering and paternal behavior and prolactin, oxytocin, and vasopressin. In the third section of the review, we discuss patterns, limitations and directions for future research. This includes discussion of conceptual and methodological issues future research might consider as well as opportunities for contributions in under-researched male life stages (juvenility, senescence) and hormones (e.g., vasopressin).

Non-invasive monitoring of physiological markers in primates

The monitoring of endocrine markers that inform about an animal's physiological state has become an invaluable tool for studying the behavioral ecology of primates. While the collection of blood samples usually requires the animal to be caught and immobilized, non-invasively collected samples of saliva, urine, feces or hair can be obtained without any major disturbance of the subject of interest. Such samples enable repeated collection which is required for matching behavioral information over long time periods with detailed information on endocrine markers. We start our review by giving an overview of endocrine and immune markers that have been successfully monitored in relation to topics of interest in primate behavioral ecology. These topics include reproductive, nutritional and health status, changes during ontogeny, social behavior such as rank relationships, aggression and cooperation as well as welfare and conservation issues. We continue by explaining which hormones can be measured in which matrices, and potential problems with measurements. We then describe different methods of hormone measurements and address their advantages and disadvantages. We finally emphasize the importance of thorough validation procedures when measuring a specific hormone in a new species or matrix.

Cortisol and DHEA in development and psychopathology

Dehydroepiandrosterone (DHEA) and cortisol are the most abundant hormones of the human fetal and adult adrenals released as end products of a tightly coordinated endocrine response to stress. Together, they mediate short- and long-term stress responses and enable physiological and behavioral adjustments necessary for maintaining homeostasis. Detrimental effects of chronic or repeated elevations in cortisol on behavioral and emotional health are well documented. Evidence for actions of DHEA that offset or oppose those of cortisol has stimulated interest in examining their levels as a ratio, as an alternate index of adrenocortical activity and the net effects of cortisol. Such research necessitates a thorough understanding of the co-actions of these hormones on physiological functioning and in association with developmental outcomes. This review addresses the state of the science in understanding the role of DHEA, cortisol, and their ratio in typical development and developmental psychopathology. A rationale for studying DHEA and cortisol in concert is supported by physiological data on the coordinated synthesis and release of these hormones in the adrenal and by their opposing physiological actions. We then present evidence that researching cortisol and DHEA necessitates a developmental perspective. Age-related changes in DHEA and cortisol are described from the perinatal period through adolescence, along with observed associations of these hormones with developmental psychopathology. Along the way, we identify several major knowledge gaps in the role of DHEA in modulating cortisol in typical development and developmental psychopathology with implications for future research.

Girls with a History of Premature Adrenarche Have Advanced Growth and Pubertal Development at the Age of 12 Years

BACKGROUND

Premature adrenarche (PA) has been linked to early thelarche and menarche, but longitudinal data on growth and pubertal development after PA are insufficient.

METHODS

Growth and pubertal development of mostly full-term and appropriate for gestational age-born 43 PA (36 girls) and 63 control children (52 girls) were analyzed prospectively. Children examined first at the mean age of 7.6 years were reexamined at the mean age of 12.0 years.

RESULTS

The PA girls but not the boys were taller and had higher body mass index (BMI) than the controls. A higher proportion of the PA than control girls had reached menarche, while the same percentage of the PA and control boys were at Tanner genital stage ≥2. The PA girls with premature pubarche (PP) were taller but not heavier and had more often reached menarche by the age of 12 years than the PA girls without PP. The PA girls with menarche had lower birth length (BL) and higher prepubertal insulin-like growth factor 1 (IGF-1) concentrations compared with non-menarcheal PA girls. In logistic regression analyses for all girls, lower BL standard deviation score, earlier maternal menarche, and higher prepubertal IGF-1 were independently associated with menarche.

CONCLUSION

At 12 years of age, the PA girls had higher BMI, advanced linear growth, and accelerated pubertal development with earlier menarche than the control girls. The PA girls with PP were taller and had earlier menarche than the PA girls without PP. Lower BL and higher prepubertal IGF-1 concentration were predictive factors for menarche by the age of 12 years.

Therapy-Induced Growth and Sexual Maturation in a Developmentally Infantile Adult Patient with a PROP1 Mutation

BACKGROUND

Hypopituitarism as a result of PROP1 (prophet of PIT1) mutation represents the most common genetic cause of combined deficiency of pituitary hormones and due to growth retardation it is typically diagnosed in childhood.

CASE DESCRIPTION

We present a unique case report of a prepubertal woman with growth retardation in whom combined pituitary hormone deficiency [central hypopituitarism, hypogonadism, and growth hormone (GH) deficiency] caused by homozygous mutation c.150delA in the PROP1 gene was diagnosed late in young adulthood due to unfavorable life circumstances. Through cautiously combined GH therapy and sex hormone therapy, she has achieved better than expected height (exceeding predictions based on family height) and sexual maturation, including regular menstrual cycles.

CONCLUSION

Early diagnosis of panhypopituitarism due to PROP1 mutation is essential for successful treatment; however, our case report shows that carefully titrated GH treatment and sex hormone substitution, although initiated in adulthood, enable restoration of physiological growth and sexual development in a hormonally infantile adult woman with a PROP1 mutation.

A systematic review of adrenarche as a sensitive period in neurobiological development and mental health

Substantial hormonal and neurobiological changes occur during puberty, and are widely argued to render this period of life a sensitive period in terms of risk for mental health problems. However, there is a paucity of research focusing on adrenarche, the earlier phase of pubertal development. Furthermore, there is a limited understanding of the association between adrenarche and neural development during this phase of life. We systematically reviewed research examining human adrenarcheal development as operationalized by hormonal levels of DHEA and DHEA-S, in relation to indices of mental health (Systematic Review 1). We then reviewed the limited amount of literature that has examined the association between adrenarcheal development and brain structure or function (Systematic Review 2). In general, studies showed that earlier timing of adrenarche was associated with greater mental health symptoms, and there is emerging support that brain development plays a role in this relationship. However, several methodological inconsistencies were noted. We propose that future research in this area test a theoretical model of adrenarche as a sensitive period of neurobiological development, whereby timing of exposure to hormones interacts with brain development, biological sex, and psychosocial stress to influence environmental sensitivity and risk for mental health problems through adolescence.

The feto-placental unit, and potential roles of dehydroepiandrosterone (DHEA) in prenatal and postnatal brain development: A re-examination using the spiny mouse

Synthesis of dehydroepiandrosterone (DHEA) by the fetal adrenal gland is important for placental oestrogen production, and may also be important for modulating the effects of glucocorticoids on the developing brain. We have preciously shown that the enzymes and accessory proteins needed for DHEA synthesis-cytochrome P450 enzyme 17α-hydroxylase/17,20 lyase (P450c17), cytochrome-b5 (Cytb5), 3β-hydroxysteroid dehydrogenase (3βHSD)-are expressed in the adrenal gland from 30 days gestation, and DHEA, cortisol and aldosterone are present in fetal plasma from this time. Explant culture of fetal adrenal tissue showed that the spiny mouse adrenal gland, can synthesize and secrete DHEA from at least 0.75 of gestation, and suggest that DHEA may have an important role(s) in placental biosynthesis of oestrogens and in modulating the actions of glucocorticoids in the developing brain in this species. Post-natally, increased immuno-expression of P450c17 and Cytb5 expression in the zona reticularis of the adrenal gland and a significant increase in the synthesis and secretion of DHEA in plasma from 8 to 20 days of age in the spiny mouse, are representative of a period of high adrenal androgen production consistent with the human phenomenon of adrenarche. The studies summarised in this review also show that DHEA is produced de novo in the developing brain of the spiny mouse. These results showed that the spiny mouse brain can indeed produce DHEA from pregnenolone in a time-dependant manner, and coupled with the identification of P450c17 and Cytb5 protein in several regions of the brain, support the idea that DHEA is an endogenous neuro-active steroid in this species. Together, the studies outlined in this review indicate that the androgen DHEA is an important hormone of adrenal and Central Nervous System (CNS) origin in the fetal and postnatal spiny mouse. Disturbance of the development of these fetal tissues, and/or of the relationship between the fetal adrenal gland and placenta during pregnancy, may have significant consequences for fetal development, placental function, and maturation of the brain. It is proposed that such disturbances of normal adrenal function could account for some of the neuropathologies that arise in juvenile and adult offspring following illness and stress experienced by the mother during pregnancy.

Ontogenetic Change in the Regional Distribution of Dehydroepiandrosterone-Synthesizing Enzyme and the Glucocorticoid Receptor in the Brain of the Spiny Mouse (Acomys cahirinus)

The androgen dehydroepiandrosterone (DHEA) has trophic and anti-glucocorticoid actions on brain growth. The adrenal gland of the spiny mouse (Acomys cahirinus) synthesizes DHEA. The aim of this study was to determine whether the brain of this precocial species is also able to produce DHEA de novo during fetal, neonatal and adult life. The expression of P450c17 and cytochrome b5 (Cytb5), the enzyme and accessory protein responsible for the synthesis of DHEA, was determined in fetal, neonatal and adult brains by immunocytochemistry, and P450c17 bioactivity was determined by the conversion of pregnenolone to DHEA. Homogenates of fetal brain produced significantly more DHEA after 48 h in culture (22.46 ± 2.0 ng/mg tissue) than adult brain homogenates (5.04 ± 2.0 ng/mg tissue; p < 0.0001). P450c17 and Cytb5 were co-expressed in fetal neurons but predominantly in oligodendrocytes and white matter tracts in the adult brain. Because DHEA modulates glucocorticoids actions, the expression of the glucocorticoid receptor (GR) was also determined. In the brainstem, medulla, midbrain, and cerebellum, the predominant GR localization changed from neurons in the fetal brain to oligodendrocytes and white matter tracts in the adult brain. The change of expression of P450c17, Cytb5 and GR proteins with cell type, brain region and developmental age indicates that DHEA is an endogenous neurosteroid in this species that may have important trophic and stress-modifying actions during both prenatal and postnatal life.

Predicting pubertal development by infantile and childhood height, BMI, and adiposity rebound

BACKGROUND

Despite substantial heritability in pubertal development, children differ in maturational tempo.

HYPOTHESES

(i) puberty and its duration are influenced by early changes in height and adiposity. (ii) Adiposity rebound (AR) is a marker for pubertal tempo.

METHODS

We utilized published prospective data from 659 girls and 706 boys of the Study of Early Child Care and Youth Development. We investigated the age of pubarche-thelarche-gonadarche-menarche as a function of early height, BMI, and AR.

RESULTS

In girls, height standard deviation scores correlated negatively with thelarche and pubarche from 15 mo of age and with menarche from 54 mo. BMI correlated negatively with thelarche from 36 mo of age and menarche from 54 mo. In boys, age at gonadarche correlated negatively with height from 36 mo of age. An AR was detected in 47% of girls and 55% of boys, who became heavier and had earlier and faster puberty than those with no AR.

CONCLUSION

The onset and tempo of puberty are influenced by a two-hit program. The first is exerted during the infancy-childhood transition (ICT; 6-12 mo) and includes height, as an early predictor of maturational tempo. The second hit occurs at the childhood-juvenility transition (5-7 y) and is based on adiposity and its rebound.

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.

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.