Puberty in girls of the 21st century

Sex ratio among childhood cancers by single year of age

BACKGROUND

The male excess in childhood cancer incidence is well-established; however, the underlying biologic mechanisms remain unknown. Examining the association between male sex and childhood cancer by single year of age and tumor type may highlight important periods of risk such as variation in growth and hormonal changes, which will inform etiologic hypotheses.

METHODS

Using data from the Surveillance, Epidemiology, and End Results (SEER) 18 registries (2000-2015), incidence rate ratios (IRR) and 95% confidence intervals (95% CI) were estimated as the measure of association between male sex and childhood cancer by single year of age (0-19).

RESULTS

The IRR for male cancer overall was 1.19 (95% CI, 1.18-1.20) and was similar in magnitude at nearly every year of age. Burkitt lymphoma was strongly associated with male sex (IRRs ≥2 at each year of age). Increased incidence was observed among males for acute lymphoblastic leukemia, Hodgkin and non-Hodgkin lymphomas for nearly all years of age. Medulloblastoma was the only central nervous system tumor with a significant male predominance at nearly every age. Male sex displayed a consistent inverse association with nephroblastoma and thyroid carcinoma over the ages studied.

CONCLUSIONS

Male sex was positively associated with most cancers. The higher incidence rates observed in males remained consistent over the childhood and adolescent periods, suggesting that childhood and adolescent hormonal fluctuations may not be the primary driving factor for the sex disparities in childhood cancer. The observed incidence disparities may be due to sex differences in exposures, genetics, or immune responses.

Is there a causal relationship between obesity and puberty?

The onset of puberty in adolescents and whether it is related to obesity is an ongoing topic for debate. Epidemiological cross-sectional and longitudinal studies show a shift towards earlier onset of puberty in girls who are obese; however, the situation is less clear in boys. Boys who are overweight seem to mature earlier, and boys who are obese mature later, than boys at a healthy weight. The underlying mechanisms are not yet fully understood, and whether earlier onset of puberty in obese girls is based on the activation of the hypothalamic-pituitary-gonadal axis is unclear. The most promising link between obesity and puberty is the adipokine leptin and its interaction with the kisspeptin system, which is an important regulator of puberty. However, peripheral action of adipose tissue (eg, via other adipokines, aromatase activity) could also be involved in changes to the onset of puberty. In addition, nutritional factors, epigenetics, or endocrine disrupting chemicals are potential mediators linking the onset of puberty to obesity. This Review summarises our knowledge concerning the relationship between obesity and onset and tempo of puberty, and the consequences of early puberty on obesity.

Timing of pubertal growth and menarche in indigenous Qom girls of Argentina

BACKGROUND

Pubertal timing is in part mediated by environmental factors, with greater energy availability often associated with earlier or more rapid development. Many indigenous populations are undergoing socioeconomic change that may affect pubertal development and related health risks, necessitating fundamental longitudinal research on growth and development in these populations.

AIM

Growth velocity and time to menarche among peri-urban indigenous Qom (Toba) girls in Argentina are described.

SUBJECTS AND METHODS

From 2011-2015, monthly anthropometrics and menstrual status were collected from 61 Qom girls aged 7-14. Growth velocity curves were generated using the 'Super-imposition by translation and rotation' (SITAR) method. Median time to menarche was estimated by Kaplan-Meier survival analysis.

RESULTS

Mean ages at peak height, weight and BMI velocity were estimated at 10.8, 10.5 and 10.7 years and median age at menarche at 11.6 years (95% CI = 11.4-11.9). At menarche, 45% of girls were overweight or obese and only one participant was short-statured by international standards.

CONCLUSION

Qom participants in this study exhibit relatively fast pubertal development as compared to other Latin American indigenous populations studied previously by others. Genetic and environmental factors influencing body size, diet and/or activity levels should be investigated further in this population.

Hospitalization for Suicide Ideation or Attempt: 2008-2015

OBJECTIVES

Suicide ideation (SI) and suicide attempts (SAs) have been reported as increasing among US children over the last decade. We examined trends in emergency and inpatient encounters for SI and SA at US children's hospitals from 2008 to 2015.

METHODS

We used retrospective analysis of administrative billing data from the Pediatric Health Information System database.

RESULTS

There were 115 856 SI and SA encounters during the study period. Annual percentage of all visits for SI and SA almost doubled, increasing from 0.66% in 2008 to 1.82% in 2015 (average annual increase 0.16 percentage points [95% confidence intervals (CIs) 0.15 to 0.17]). Significant increases were noted in all age groups but were higher in adolescents 15 to 17 years old (average annual increase 0.27 percentage points [95% CI 0.23 to 0.30]) and adolescents 12 to 14 years old (average annual increase 0.25 percentage points [95% CI 0.21 to 0.27]). Increases were noted in girls (average annual increase 0.14 percentage points [95% CI 0.13 to 0.15]) and boys (average annual increase 0.10 percentage points [95% CI 0.09 to 0.11]), but were higher for girls. Seasonal variation was also observed, with the lowest percentage of cases occurring during the summer and the highest during spring and fall.

CONCLUSIONS

Encounters for SI and SA at US children's hospitals increased steadily from 2008 to 2015 and accounted for an increasing percentage of all hospital encounters. Increases were noted across all age groups, with consistent seasonal patterns that persisted over the study period. The growing impact of pediatric mental health disorders has important implications for children's hospitals and health care delivery systems.

Childhood and adolescent phenol and phthalate exposure and the age of menarche in Latina girls

BACKGROUND

The age of menarche has been associated with metabolic and cardiovascular disease, as well as cancer risk. The decline in menarcheal age over the past century may be partially attributable to increased exposure to endocrine disrupting chemicals (EDCs).

METHODS

We assessed the influence of 26 phenol and phthalate biomarkers on the timing of menarche in a longitudinal cohort of Chilean girls. These EDCs were quantified in urine collected prior to the onset of breast development (Tanner 1; B1), and during adolescence (Tanner 4; B4). Multivariable accelerated failure time (AFT) models were used to analyze associations between biomarker concentrations and the age of menarche adjusting for body mass index (BMI) Z-score and maternal education, accounting for within-subject correlation.

RESULTS

Several biomarkers were significantly associated with the age at menarche; however, these associations were dependent on the timing of biomarker assessment. A log(ng/ml) increase in B1 concentrations of di(2-ethylhexyl) phthalate biomarkers was associated with later menarche (hazard ratio (HR): 0.77; 95% CI: 0.60, 0.98), whereas higher B1 concentrations of 2,5-dichlorophenol and benzophenone-3 were associated with earlier menarche (HR: 1.13; 95% CI: 1.01, 1.27; HR: 1.17; 95% CI: 1.06, 1.29, respectively). Elevated B4 concentrations of monomethyl phthalate were similarly associated with earlier menarche (HR: 1.30; 95% CI: 1.10, 1.53). The impact of monoethyl phthalate and triclosan concentrations on pubertal timing were significantly modified by BMI Z-score. Higher monoethyl phthalate and triclosan concentrations were associated with earlier menarche among overweight or obese girls, but not among those that were normal weight.

CONCLUSIONS

This study identifies modulation of sexual maturation by specific EDC biomarkers in Latina girls.

Age of pubertal events among school girls in Lagos, Nigeria

BACKGROUND

Globally, there is a secular trend towards the reduced age for sexual maturity and menarche. This study aimed to determine the current age and factors associated with attainment of various stages of puberty in Nigerian girls.

METHODS

This study was a cross-sectional study involving 800 girls aged 6-15 years. The subjects were selected by stratified random sampling method from schools in Oshodi Local Government Area, Lagos State. They were interviewed and a physical examination was carried out to classify them into the various Tanner stages of breast and pubic hair maturational stages.

RESULTS

The median age of girls at first stage of breast maturation (B2), first stage of pubic hair development (PH2) and at menarche were 9.0, 9.0 and 12.0 years, respectively. Breast development was significantly related to normal nutritional status (adjusted odds ratio [AOR] 4.5, p<0.001), overweight (AOR 40.2, p<0.001), obesity (AOR 154.2, p<0.001) and upper social class (AOR 15.7, p<0.031). Pubic hair development was significantly related only to overweight (AOR 4.7, p<0.007) and obesity (AOR 15.7, p<0.001) while achievement of menarche was significantly related to overweight (AOR 0.1, p=0.005), obesity (AOR 0.1, p=0.0009), high social class (AOR 4.7, p<0.001) and being a member of the Hausa tribe (AOR 35.8, p<0.029).

CONCLUSIONS

There is decline in age of pubertal maturation of girls in Nigeria and the major contributory factors appear to be overweight and obesity. These findings are consistent with the pattern in developed countries.

Consumption of soy-based infant formula is not associated with early onset of puberty

PURPOSE

The use of soy products is common in young children with cow milk allergy (CMA). The aim was to examine prospectively the association between infantile consumption of soy-based formula, growth parameters and early pubertal signs, in comparison to cow milk-based formula.

METHODS

A nested case-control study was conducted, selected from a cohort of infants prospectively followed from birth until the age of 3 years for eating habits and the development of IgE-mediated CMA. Infants who consumed only soy-based formula were included in the soy group. The control group was randomly selected from those without IgE-CMA and not receiving soy formula. Study participants were reevaluated between ages 7.8 and 10.5 years by an interview, nutritional intake by 3 days diaries, and height, weight, and pubertal signs by physical examination.

RESULTS

The soy-fed group included 29 participants (17 males), median age 8.92 years IQR (8.21, 9.42). The control group included 60 participants (27 males), median age 8.99 years IQR (8.35, 9.42). The groups had comparable height and BMI z scores (- 0.17 ± 1.08 versus - 0.16 ± 1.01, p = 0.96, and 0.67 ± 1.01 versus 0.53 ± 1.02, p = 0.56, for soy and control groups, respectively). Four (three males and one female) from the soy-group (13.8%) and eight females from the control-group (13.3%) had early pubertal signs (p = 0.95). No association was detected between puberty and infantile nutrition, after controlling for BMI and family data. No association with puberty or differences between groups were found in current daily consumption of soy, micronutrients, energy, carbohydrates, fat, and protein.

CONCLUSIONS

This is the first prospective, physical examination-based study, demonstrating no association between infantile soy-based formula consumption and growth and puberty parameters.

Faster ticking rate of the epigenetic clock is associated with faster pubertal development in girls

Epigenetic age is an indicator of biological aging, capturing the impact of environmental and behavioral influences across time on cellular function. Deviance between epigenetic age and chronological age (AgeAccel) is a predictor of health. Pubertal timing has similarly been associated with cancer risk and mortality rate among females. We examined the association between AgeAccel and pubertal timing and adolescent breast composition in the longitudinal Growth and Obesity Cohort Study. AgeAccel was estimated in whole blood using the Horvath method at breast Tanner 2 (B2) and 4 (B4). Total breast volume, absolute fibro-glandular volume (FGV), and %FGV were evaluated at B4 using dual X-ray absorptiometry. The impact of AgeAccel (mean: 0; SD: 3.78) across puberty on the time to breast development (thelarche), menarche, and pubertal tempo (thelarche to menarche) was estimated using accelerated failure time models; generalized estimating equations were used to evaluate associations with breast density. A five-year increase in average adolescent AgeAccel was associated with a significant decrease in time to menarche [hazard ratio (HR): 1.37; 95% confidence interval (CI): 1.04, 1.80] adjusting for birth weight, maternal pre-pregnancy body mass index, maternal height, maternal education, B2 height, fat percentage, and cell composition. AgeAccel displayed a stronger inverse association with pubertal tempo (HR: 1.48; 95% CI: 1.10, 1.99). A five-year increase in AgeAccel was associated with 5% greater %FGV, adjusting for B4 percent body fat, and maternal traits (95% CI: 1.01, 1.10). Our study provides unique insight into the influence of AgeAccel on pubertal development in girls, which may have implications for adult health.

Reference and Influential Factors of Serum Bone Markers in Chinese Adolescents

This study aimed to establish reference ranges of bone markers in Chinese adolescents between the age of 12 and 16, and to search these markers’ characteristics and influential factors. Personal information and fasting blood samples were collected from 174 healthy adolescents in Northeast China. Serum levels of PINP, ALP, β-CrossLaps, calcium, phosphate, PTH, 25(OH)D and TSH were measured. Reference ranges were established for PINP [(85.55–2,028.75)ng/ml], ALP [(53.88–463.63)U/L], β-CrossLaps [(0.16–1.19)ng/ml], calcium [(2.35–2.70)mmol/L], phosphate [(1.17–2.06)mmol/L] and PTH [(2.64–43.36)μg/L] in this population. We observed that bone formation markers PINP and ALP levels were evidently higher when compared to kit references for adults. Reference ranges for calcium, phosphate and PTH also differed from those provided by kit manuals. Serum ALP, PINP, phosphate and PTH changed with age (all P < 0.005), and were significantly higher in boys than in girls (all P < 0.05). Serum 25(OH)D and TSH levels didn’t correlate with PINP, ALP and β-CrossLaps (all P > 0.05). In conclusion, unique reference ranges should be provided for adolescents. BMI, sex and age independently influence certain serum bone markers in adolescents. Vitamin D deficiency is widespread. Serum levels of vitamin D and TSH may not influence bone turnover markers in this population.

A high salt diet inhibits obesity and delays puberty in the female rat

BACKGROUND/OBJECTIVES

Processed foods are considered major contributors to the worldwide obesity epidemic. In addition to high sugar and fat contents, processed foods contain large amounts of salt. Owing to the correlations with rising adiposity, salt has recently been proposed to be obesogenic. This study investigated three hypotheses: (i) high salt contributes to weight gain and adiposity in juvenile female rats, (ii) puberty onset would be altered because salt is known to affect neuronal systems involved in activating the reproductive system, and (iii) enhanced adiposity will act synergistically with salt to drive early puberty onset.

DESIGN

Female weanling rats (post-natal day 21, n=105) were fed a low fat/low salt diet, low fat/high salt diet, high fat/low salt diet or a high salt/high fat diet for 24 days. Metabolic measures, including weight gain, food intake, fecal output, activity and temperature were recorded in subsets of animals.

RESULTS

Body weight, retroperitoneal and perirenal fat pad weight, and adipocyte size were all lower in animals fed high fat/high salt compared with animals fed high fat alone. Leptin levels were reduced in high fat/high salt fed animals compared with high fat/low salt-fed animals. Daily calorie intake was higher initially but declined with adjusted food intake and was not different among groups after 5 days. Osmolality and corticosterone were not different among groups. Fecal analysis showed excess fat excretion and a decreased digestive efficiency in animals fed high fat/low salt but not in animals fed high fat/high salt. Although respiratory exchange ratio was reduced by high dietary fat or salt, aerobic-resting metabolic rate was not affected by the diet. High salt delayed puberty onset, regardless of dietary fat content.

CONCLUSIONS

Salt delays puberty and prevents the obesogenic effect of a high fat diet. The reduced weight gain evident in high salt-fed animals is not due to differences in food intake or digestive efficiency.

Birth weight, early life weight gain and age at menarche: a systematic review of longitudinal studies

BACKGROUND AND OBJECTIVE

Adiposity in pre- and postnatal life may influence menarcheal age. Existing evidence is primarily cross-sectional, failing to address temporality, for which the role of adiposity in early life remains unclear. The current study sought to systematically review longitudinal studies evaluating the associations between birth weight and infant/childhood weight status/weight gain in relation to menarcheal age.

METHODS

PubMed, EMBASE, Web of Science, Global Health (Ovid) and CINAHL were systematically searched. Selected studies were limited to English-language articles presenting multi-variable analyses. Seventeen studies reporting risk estimates for birth weight (n = 3), infant/childhood weight gain/weight status (n = 4) or both (n = 10), in relation to menarcheal age were included.

RESULTS

Lower vs. higher birth weight was associated with earlier menarche in nine studies and later menarche in one study, while three studies reported a null association. Greater BMI or weight gain over time and greater childhood weight were significantly associated with earlier menarche in nine of nine and six of seven studies, respectively.

CONCLUSIONS

Studies suggested that lower birth weight and higher body weight and weight gain in infancy and childhood may increase the risk of early menarche. The pre- and postnatal period may thus be an opportune time for weight control interventions to prevent early menarche, and its subsequent consequences.

Pubertal development in girls by breast cancer family history: the LEGACY girls cohort

Background

Pubertal milestones, such as onset of breast development and menstruation, play an important role in breast cancer etiology. It is unclear if these milestones are different in girls with a first- or second-degree breast cancer family history (BCFH).

Methods

In the LEGACY Girls Study (n = 1040), we examined whether three mother/guardian-reported pubertal milestones (having reached Tanner Stage 2 or higher (T2+) for breast and pubic hair development, and having started menstruation) differed by BCFH. We also examined whether associations between body size and race/ethnicity and pubertal milestones were modified by BCFH. We used mother/guardian reports as the primary measure of pubertal milestones, but also conducted sensitivity analyses using clinical Tanner measurements available for a subcohort (n = 204). We analyzed cross-sectional baseline data with logistic regression models for the entire cohort, and longitudinal data with Weibull survival models for the subcohort of girls that were aged 5–7 years at baseline (n = 258).

Results

BCFH was modestly, but not statistically significantly, associated with Breast T2+ (odds ratio (OR) = 1.36, 95% confidence interval (CI) = 0.88–2.10), with a stronger association seen in the subcohort of girls with clinical breast Tanner staging (OR = 2.20, 95% CI = 0.91–5.32). In a longitudinal analysis of girls who were aged 5–7 years at baseline, BCFH was associated with a 50% increased rate of having early breast development (hazard ratio (HR) = 1.49, 95% CI = 1.0–2.21). This association increased to twofold in girls who were not overweight at baseline (HR = 2.04, 95% CI = 1.29–3.21). BCFH was not associated with pubic hair development and post-menarche status. The median interval between onset of breast development and menarche was longer for BCFH+ than BCFH– girls (2.3 versus 1.7 years), suggesting a slower developmental tempo for BCFH+ girls. Associations between pubertal milestones and body size and race/ethnicity were similar in girls with or without a BCFH. For example, weight was positively associated with Breast T2+ in both girls with (OR = 1.06 per 1 kg, 95% CI = 1.03–1.10) and without (OR = 1.14 per 1 kg, 95% CI = 1.04–1.24) a BCFH.

Conclusions

These results suggest that BCFH may be related to earlier breast development and slower pubertal tempo independent of body size and race/ethnicity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0849-y) contains supplementary material, which is available to authorized users.

Adult height after spontaneous pubertal growth or GnRH analog treatment in girls with early puberty: a meta-analysis

Early puberty (EP) has been defined as the onset of puberty in the low-normal range; it may be a cause for concern regarding a possible impairment of adult height (AH). This paper meta-analysed data on AH after spontaneous growth or after gonadotropin-releasing hormone (GnRH) analog treatment in girls with EP. A computerized literature search was conducted from 1980 to June 30, 2016. Only published studies in English were considered. Eight papers were selected (483 cases). In untreated girls (n = 300), predicted adult height (PAH) at start of follow-up (-0.559 SDS (95%CI -1.110 to 0.001); P = 0.050) was close to mid-parental height (MPH) (-0.557 SDS (95%CI -0.736 to -0.419); P < 0.0001) and AH (-0.663 SDS (95%CI -0.803 to -0.524); P < 0.0001). In GnRH analog treated girls (n = 183), PAH before the start of treatment was slightly reduced (-0.939 SDS (95%CI -1.401 to -0.477; P < 0.0001) vs MPH (-0.678 SDS (95%CI -0.942 to -0.414); P < 0.0000), but AH (-0.604 SDS (95%CI -0.877 to -0.338); P < 0.0000) was close to MPH.

CONCLUSION

Present meta-analysis indicates that girls with EP spontaneously reach their MPH and that GnRH analog treatment does not widely change growth outcome. Differences among the selected studies for definition of EP, inclusion criteria, treatment duration, age at discontinuation of therapy, definition of AH may affect results. What is Known: • Early puberty represents a main cause of consultation in paediatric endocrinology offices due to concerns of both practitioners and parents. • Treatment with GnRH analogs is sometimes attempted with the aim to improve adult height. What is New: • Untreated and GnRH analog treated girls with early puberty reached similar adult height. • Adult height was consistent with mid-parental height in both untreated and GnRH analog treated girls with early puberty.

Exposure to phytoestrogens in utero and age at menarche in a contemporary British cohort

Phytoestrogens are estrogenic compounds that occur naturally in plants. Phytoestrogens can cross the placenta, and animal studies have found associations between in utero exposure to phytoestrogens and markers of early puberty. We investigated the association between in utero exposure to phytoestrogens and early menarche (defined as <11.5 years of age at onset) using data from a nested case-control study within the Avon Longitudinal Study of Parents and Children, a longitudinal study involving families living in the South West of England. Concentrations of six phytoestrogens were measured in maternal urine samples collected during pregnancy. Logistic regression was used to explore associations between tertiles of phytoestrogen concentrations and menarche status, with adjustment for maternal age at menarche, maternal education, pre-pregnancy body mass index (BMI), child birth order, duration of breastfeeding, and gestational age at sample collection. Among 367 mother-daughter dyads, maternal median (interquartile range) creatinine-corrected concentrations (in µg/g creatinine) were: genistein 62.1 (27.1-160.9), daidzein 184.8 (88.8-383.7), equol 4.3 (2.8-9.0), O-desmethylangolensin (O-DMA) 13.0 (4.4-34.5), enterodiol 76.1 (39.1-135.8), and enterolactone 911.7 (448.1-1558.0). In analyses comparing those in the highest tertile relative to those in the lowest tertile of in utero phytoestrogen exposure, higher enterodiol levels were inversely associated with early menarche (odds ratio (OR)=0.47; 95% confidence interval (CI): 0.26-0.83), while higher O-DMA levels were associated with early menarche (OR=1.89; 95% CI: 1.04-3.42). These findings suggest that in utero exposure to phytoestrogens may be associated with earlier age at menarche, though the direction of association differs across phytoestrogens.

Gynecologic and Obstetric Consequences of Obesity in Adolescent Girls

In the past few decades, there has been an overwhelming increase in childhood and adolescent obesity worldwide. Besides the well recognized cardiometabolic complications and other physical conditions associated with obesity, during adolescence, it causes psychological and social distress in a period of life that is already sensitive for a girl. This in turn increases their risk of low self-esteem and depression. Furthermore, obesity diminishes health-related quality of life and years of life. Overweight and obese teenagers are more likely to have gynecologic and obstetric complications, during adolescence and also later in life. Consequences of obese and overweight childhood and adolescence include sexual maturation and reproductive dysfunction, alterations in menstruation, dysmenorrhea, risky sexual behavior, and inefficient use of contraception, polycystic ovary syndrome, bone density abnormalities, macromastia, and an increased risk of breast and endometrial cancer. Obese adolescents are at greater risk of pregnancy and perinatal complications, such as preeclampsia, gestational hypertension and preeclampsia, gestational diabetes mellitus, primary cesarean delivery, and induction of labor, to mention a few. Evidence shows that infants born to obese teenagers are also more likely to have complications including preterm or post-term delivery, small-for-gestational age newborns, macrosomia, meconium aspiration, respiratory distress, and even stillbirth, among others. This comprehensive review focuses on the gynecological and obstetric consequences of obesity in adolescent girls.

Non-invasive optical spectroscopic monitoring of breast development during puberty

Background

Tanner staging (TS), a five-stage classification indicating no breast tissue (TS1) to full breast development (TS5), is used both in health research and clinical care to assess the onset of breast development (TS2) and duration in each stage. Currently, TS is measured both visually and through palpation but non-invasive methods will improve comparisons across settings.

Methods

We used optical spectroscopy (OS) measures from 102 girls at the Ontario site of the LEGACY girls study (average age 12 years, range 10.0–15.4 years) to determine whether breast tissue optical properties map to each TS. We further examined whether these properties differed by age, body mass index (BMI), and breast cancer risk score (BCRS) by examining the major principal components (PC).

Results

Age and BMI increased linearly with increasing TS. Eight PCs explained 99.9% of the variation in OS data. Unlike the linear increase with age and BMI, OS components had distinct patterns by TS: the onset of breast development (TS1 to TS2) was marked by elevation of PC3 scores indicating an increase in adipose tissue and decrease in signal from the pectoral muscle; transition to TS3 was marked by elevation of PC6 and PC7 and decline of PC2 scores indicating an increase in glandular or dense tissue; and transition to TS4+ by decline of PC2 scores representing a further increase in glandular tissue relative to adipose tissue. Of the eight PCs, three component scores (PC4, PC5, and PC8) remained in the best-fitting model of BCRS, suggesting different levels of collagen in the breast tissue by BCRS.

Conclusions

Our results suggest that serial measures of OS, a non-invasive assessment of breast tissue characteristics, can be used as an objective outcome that does not rely on visual inspection or palpation, for studying drivers of breast development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0805-x) contains supplementary material, which is available to authorized users.

Physical activity induced protection against breast cancer risk associated with delayed parity

Epidemiological evidence indicates that physical activity between menarche and first pregnancy is associated with a lower risk of breast cancer among women with at least 20years between these reproductive events. The mechanism by which physical activity during this interval confers protection is unknown. This study used a novel animal model to assess potentially protective effects of physical activity on tumor development in delayed parity. Thirty-six female Sprague Dawley rats received an i.p. injection of 50mg/kg N-methyl-N-nitrosourea (MNU) at 5weeks of age. Estrogen and progesterone pellets were implanted subcutaneously 1week (early parity, EP, n=8) or 4weeks (delayed parity, DP, n=11) following MNU injection. An additional group of DP rats were progressively exercise trained (Ex+DP, n=9) on a treadmill following MNU injection for 7weeks (up to 20m/min at 15% incline for 30min). We observed the greatest tumor latency and smallest tumor burden in Ex+DP animals. Ductal hyperplasia and inflammation of non-tumor bearing mammary glands were only found in DP, and we detected a significant increase in collagen for DP and Ex+DP compared to EP. Exercise induced differential gene expression of cyclin-dependent kinase-inhibitor 1C (Cdkn1c) and urokinase-plasminogen activator (Plau) in mammary tissue of Ex+DP animals compared to DP alone. While there are delayed parity-induced changes in mammary gland collagen and gene expression levels, Ex+DP animals had longer tumor latency, smaller tumor burden, and glandular tissue resistant to ductal hyperplasia. Exercise may induce protection through beneficial regulation of gene expression profiles.

Commercially available lifestyle modification program: randomized controlled trial addressing heart and bone health in BRCA1/2+ breast cancer survivors after risk-reducing salpingo-oophorectomy

PURPOSE

The goal of this RCT was to examine the efficacy and safety of a web-based program to improve cardiovascular and bone health outcomes, among 35 BRCA1/2+ breast cancer survivors who underwent prophylactic oophorectomy and thus experienced premature surgical menopause.

METHODS

A 12-month commercially available web-based lifestyle modification program (Precision Nutrition Coaching) was utilized. Cardiovascular fitness, dietary intake, leisure time activity, body composition, bone mineral density, bone structure, and muscle strength were assessed.

RESULTS

Average adherence to all program components was 74.8 %. Women in the intervention group maintained their cardiovascular fitness level over the 12 months (1.1 ± 7.9 %), while the control group significantly decreased fitness capacity (-4.0 ± 7.5 %). There was a significant difference between groups in percent change of whole body bone area (-0.8 ± 2.5 control and 0.5 ± 1.30 intervention). We also observed decreased BMI (-4.7 ± 6.2 %) and fat mass (-8.6 ± 12.7 %) in the intervention group due to significant concomitant decreases in caloric intake and increases in caloric expenditure. The control group demonstrated decreased caloric intake and decreased lean tissue mass.

CONCLUSIONS

In this population at high risk for detrimental cardiovascular and bone outcomes, a commercially available lifestyle intervention program mitigated a decline in cardiovascular health, improved bone health, and decreased weight through fat loss.

IMPLICATIONS FOR CANCER SURVIVORS

Precision Nutrition Coaching has shown benefit in breast cancer survivors for reduced risk of deleterious cardiovascular and bone outcomes.

Immaturity in puberty and negative attitudes toward reproductive health among Indonesian adolescents

BACKGROUND

Complex factors influence adolescents' attitudes. Secondary sexual development and emotional changes are markers of puberty and affect attitudes toward reproductive health (RH). This is especially evident in the society and culture of Indonesia. This study examined the presence of immaturity at puberty and factors associated with negative attitudes toward RH among Indonesian adolescents.

METHODS

We conducted a cross-sectional study with 1040 students (aged 11-16 years) selected using multistage random cluster sampling. Data were collected using a self-administered questionnaire that included the illustrative questionnaire for interview surveys with young people and the pubertal development scale (PDS), modified in accordance with the Indonesian context. Data analysis used descriptive and comparative statistics and logistic regression analyses.

RESULTS

Immature pubertal development was higher in boys [22.7%, 95% confidence interval (CI): 14.7%-30.7%] than girls (18.4%, 95% CI: 11%-25.7%). However, negative attitudes were higher in girls (40.6%, 95% CI: 34.3%-46.8%) than boys (37.1%, 95% CI: 29.9%-44.7%). Factors associated with negative attitudes toward RH in both boys and girls were age, RH communication with parents, and pubertal development. Smoking was an additional factor in boys, whereas living in an urban area was an additional factor in girls. High knowledge about RH was associated with less negative attitudes toward RH in both boys and girls.

CONCLUSION

Immaturity and factors that influence negative attitudes toward RH should be explored during puberty. Improving knowledge about RH may help to prevent negative attitudes toward RH, especially for girls in urban areas and boys with smoking habits.

Age at Menarche and Its Association with Excess Weight and Body Fat Percentage in Girls in the Southwestern Region of the Brazilian Amazon

STUDY OBJECTIVE

To analyze age at menarche and its association with excess weight and body fat percentage.

DESIGN

School-based cross-sectional survey.

SETTING

Southwestern region of the Brazilian Amazon.

PARTICIPANTS

The sample was made up of 727 girls, in the 8- to 16-year age range, divided into 3 groups: early, normal, and late menarche, from public and private schools, selected through proportional stratified random sampling.

INTERVENTIONS AND MAIN OUTCOME MEASURES

Bioimpedance was used to measure body fat percentage and body mass index, applying the Global School-Based Student Health Survey questionnaire to categorize behavior variables. Age at menarche was determined using the status quo method. Sexual maturity was assessed through self-assessment according to criteria described by Tanner.

RESULTS

Overall age at menarche was 11.52 (±1.35), early 10.48 (±0.78), normal 12.39 (±0.50) and late 14.27 (±0.51) years. Prevalence of excess weight and body fat was 28.3% (206/727) and 44.3% (322/727), among those with menarche. There was a positive association between excess weight and body fat with age at early menarche (P = .000 and .015).

CONCLUSION

Age at menarche among girls from the Amazon region is similar to that of industrialized countries. Prevalence of excess weight and body fat was high, and there was evidence of an association between age with early menarche and excess weight. Trends in age at menarche and stage of sexual maturation should be monitored with related factors, to adopt obesity control strategies from an early age.

Residential proximity to traffic and female pubertal development

BACKGROUND

Traffic-related air pollution (TRAP) has been linked with several adverse health outcomes, including preterm birth and low birth weight, which are both related to onset of puberty. No studies to date have investigated the association between TRAP and altered pubertal timing.

OBJECTIVE

Determine the association between residential proximity to traffic, as a marker of long-term TRAP exposure, and age at pubertal onset in a longitudinal study of girls.

METHODS

We analyzed data for 437 girls at the CYGNET study site of the Breast Cancer and Environment Research Program. TRAP exposure was assessed using several measures of residential proximity to traffic based on address at study entry. Using accelerated failure time models, we calculated time ratios (TRs) and their corresponding 95% confidence intervals (CIs) for specified traffic metrics and pubertal onset, defined as stage 2 or higher for breast or pubic hair development (respectively, B2+ and PH2+). Models were adjusted for race/ethnicity, household income, and cotinine levels.

RESULTS

At baseline, 71% of girls lived within 150m of a major road. The median age of onset was 10.3years for B2+ and 10.9years for PH2+. Living within 150m downwind of a major road was associated with earlier onset of PH2+ (TR 0.96, 95% CI 0.93, 0.99). Girls in the highest quintile of either distance-weighted traffic density, annual average daily traffic, and/or traffic density also reached PH2+ earlier than girls in the lowest quintiles.

CONCLUSIONS

In this first study to assess the association between residential proximity to traffic and pubertal onset we found girls with higher exposure reached one pubertal milestone several months earlier than low exposed girls, even after consideration of likely confounders. Results should be expanded in larger epidemiological studies, and with measured levels of air pollutants.

Infection and pubertal timing: a systematic review

The decline in age of pubertal timing has serious public health implications ranging from psychosocial adjustment problems to a possible increase in reproductive cancers. One biologically plausible explanation for the decline is a decrease in exposures to infections. To systematically review studies that assess the role of infection in pubertal timing, Medline, Web of Science and EMBASE were systematically searched and retrieved studies were reviewed for eligibility. Eligible studies examined the association between infections, including microbial exposures, and physical pubertal characteristics (breast, genitalia and pubic hair development) or age at menarche. We excluded studies that were published in a language other than English, focused on precocious puberty, were case studies, and/or included youth with autoimmune diseases. We report on study design, population characteristics, measurement of infection and puberty and the main effects of infection on pubertal development. Based on our search terms we identified 1372 unique articles, of which only 15 human and five animal studies met our eligibility criteria. Not all studies examined all outcomes. Infection was associated with later breast development (4/4 human studies), with less consistent evidence for genitalia and pubic hair development. Seven studies assessed age at menarche with inconsistent findings (three supporting later, four no association). We conclude that a small but consistent literature supports that infection is associated with later breast development; the evidence for other pubertal events and age at menarche is less clear. Where fewer childhood infections coincide with the rise in incidence of hormone-related cancers.

The Relationship Between Greater Prepubertal Adiposity, Subsequent Age of Maturation, and Bone Strength During Adolescence

This longitudinal study investigated whether greater prepubertal adiposity was associated with subsequent timing of maturation and bone strength during adolescence in 135 girls and 123 boys participating in the Iowa Bone Development Study. Greater adiposity was defined using body mass index (BMI) data at age 8 years to classify participants as overweight (OW, ≥85th percentile for age and sex) or healthy weight (HW). Maturation was defined as the estimated age of peak height velocity (PHV) based on a series of cross-sectional estimates. Measurements were taken at ages 11, 13, 15, and 17 years for estimates of body composition by dual-energy X-ray absorptiometry (DXA), bone compression (bone strength index), and torsion strength (polar strength-strain index) at the radius and tibia by pQCT, and femoral neck bending strength (section modulus) by hip structural analysis. Bone strength in OW versus HW were evaluated by fitting sex-specific linear mixed models that included centered age (visit age - grand mean age of cohort) as the time variable and adjusted for change in fat mass, and limb length in model 1. Analyses were repeated using biological age (visit age - age PHV) as the time variable for model 1 with additional adjustment for lean mass in model 2. BMI was negatively associated with age of maturation (p < 0.05). OW versus HW girls had significantly greater bone strength (p < 0.001) in model 1, whereas OW versus HW boys had significantly greater bone strength (p < 0.001) at the tibia and femoral neck but not radius (p > 0.05). Analyses were repeated using biological age, which yielded reduced parameter estimates for girls but similar results for boys (model 1.) Differences were no longer present after adjustment for lean mass (model 2) in girls (p > 0.05) whereas differences at the tibia were sustained in boys (p < 0.05). These findings demonstrate sex- and site-specific differences in the associations between adiposity, maturation, and bone strength. © 2016 American Society for Bone and Mineral Research.

Updates in preserving reproductive potential of prepubertal girls with cancer: Systematic review

INTRODUCTION

With increasing numbers of adult female survivors of childhood cancers due to advances in early diagnosis and treatment, the issue of preserving the reproductive potential of prepubertal girls undergoing gonadotoxic treatments has gained greater attention.

METHODS

According to PRISMA guidelines, a systematic review of the literature was performed for all relevant full-text articles published in PubMed in English throughout the past 15 years to explore the significant updates in preserving the reproductive potential of prepubertal girls with cancer.

RESULTS

The two established fertility preservation options, embryo freezing and egg freezing, cannot be offered routinely to prepubertal girls as these options necessitate prior ovarian stimulation and subsequent mature oocytes retrieval that are contraindicated or infeasible before puberty. Therefore, the most suitable fertility preservation options to prepubertal girls are (1) ovarian tissue freezing and autotransplantation, (2) in vitro maturation, and (3) ovarian protection techniques. In this review, we discuss in detail those options as well as their success rates, advantages, disadvantages and future directions. We also suggest a new integrated strategy to preserve the reproductive potential of prepubertal girls with cancer.

CONCLUSION

Although experimental, ovarian tissue slow freezing and orthotopic autotransplantation may be the most feasible option to preserve the reproductive potential of prepubertal girls with cancer. However, this technique has two major and serious disadvantages: (1) the risk of reintroducing malignant cells, and (2) the relatively short lifespan of ovarian tissue transplants. Several medical and ethical considerations should be taken into account before applying this technique to prepubertal girls with cancer.

Fatness rather than leptin sensitivity determines the timing of puberty in female mice

Leptin is a permissive factor for the onset of puberty. However, changes in adiposity frequently influence leptin sensitivity. Thus, the objective of the present study was to investigate how changes in body weight, fatness, leptin levels and leptin sensitivity interact to control the timing of puberty in female mice. Pre-pubertal obesity, induced by raising C57BL/6 mice in small litters, led to an early puberty onset. Inactivation of Socs3 gene in the brain or exclusively in leptin receptor-expressing cells reduced the body weight and leptin levels at pubertal onset, and increased leptin sensitivity. Notably, these female mice exhibited significant delays in vaginal opening, first estrus and onset of estrus cyclicity. In conclusion, our findings suggest that increased leptin sensitivity did not play an important role in favoring pubertal onset in female mice. Rather, changes in pubertal body weight, fatness and/or leptin levels were more important in influencing the timing of puberty.

The Health Consequences of Obesity in Young Adulthood

Young adults are gaining weight faster than any age group. This weight gain and the appearance of obesity-related comorbidities often commence in adolescence. Psychosocial distress and mental health issues are common and debilitating, and treatment approaches are likely to be similar to those for adolescents. At the same time, young adults may have physical morbidities which will continue and worsen throughout adulthood, such as hypertension, diabetes and polycystic ovarian syndrome. Health consequences of obesity are challenging to manage in young adults as their symptoms may be minimal, they are less likely to engage with healthcare due to other life priorities and their neurocognitive developmental stage makes therapy adherence difficult. Clinicians who manage young adults with obesity need to be aware of these age-specific challenges, as well as the sexual and reproductive health concerns that are present in this age group.

Pattern of teen menstruation among secondary school girls in south east Nigeria

BACKGROUND

Menstruation in the teenage age has assumed variable trends which is been influenced by several variables. This study is aimed at determining the pattern and trend of menstruation among teens attending secondary school in south east Nigeria and associated factors.

METHODS

Menstruation patterns were investigated using a stratified random sampling method of teens from junior secondary schools in Enugu, south east Nigeria. A self-administered questionnaire was developed and data analyzed using SPSS version 19.

RESULTS

A total of 897 female teenagers aged 9-18 years completed the questionnaire with a mean age of 13.9±1.9 years. The mean age (SD) at onset of menarche was 12.5±1.2 years. Teenage girls with higher BMI achieved menarche earlier at age 8 and 9 when compared with their counterparts with lower BMI and this is statistically significant. F=7.60, df=8, p<0.001. Teens with a 14-day cycle had a higher BMI when compared with teens with longer cycle but this is not statistically significant. F=1.05, df=4, p=0.381. There is a statistical significance difference between teens duration of menstrual flow and BMI. Those with higher BMI had longer duration(4-5 days) compared with those with lower BMI. F=3.329, df=4, p=0.01 CONCLUSIONS: This study revealed that the mean age at onset of menarche was 12.5±1.2 years showing a continuing decreasing trend. Teens with higher BMI attain menarche earlier and had longer days of periods when compared with their counterpart with lower BMI.

Does salt have a permissive role in the induction of puberty?

Puberty is starting earlier than ever before and there are serious physiological and sociological implications as a result of this development. Current research has focused on the potential role of high caloric, and commensurate high adiposity, contributions to early puberty. However, girls with normal BMI also appear to be initiating puberty earlier. Westernized diets, in addition to being high in fat and sugar, are also high in salt. To date, no research has investigated a link between elevated salt and the reproductive axis. We hypothesize that a high salt diet can result in an earlier onset of puberty through three mechanisms that are not mutually exclusive. (1) High salt activates neurokinin B, a hormone that is involved in both the reproductive axis and salt regulation, and this induces kisspeptin release and ultimate activation of the reproductive axis. (2) Vasopressin released in response to high salt acts on vasopressin receptors expressed on kisspeptin neurons in the anteroventral periventricular nucleus, thereby stimulating gonadotropin releasing hormone and subsequently luteinizing hormone secretion. (3) Salt induces metabolic changes that affect the reproductive axis. Specifically, salt acts indirectly to modulate adiposity, ties in with the obesity epidemic, and further compounds the pathologic effects of obesity. Our overall hypothesis offers an additional cause behind the induction of puberty and provides testable postulates to determine the mechanism of potential salt-mediated affects on puberty.

Ambient ozone exposure and children's acute asthma in New York City: a case-crossover analysis

BACKGROUND

Childhood asthma morbidity has been associated with ambient ozone in case-crossover studies. Varying effects of ozone by child age and sex, however, have been less explored.

METHODS

This study evaluates associations between ozone exposure and asthma emergency department visits and hospitalizations among boys and girls aged 5-17 years in New York City for the 2005-2011 warm season period. Time-stratified case-crossover analysis was conducted and, for comparison, time-series analysis controlling for season, day-of-week, same-day and delayed effects of temperature and relative humidity were also performed.

RESULTS

We found associations between ambient ozone levels and childhood asthma emergency department visits and hospitalizations in New York City, although the relationships varied among boys and girls and by age group. For an increase of interquartile range (0.013 ppm) in ozone, there was a 2.9-8.4% increased risk for boys and 5.4-6.5% for girls in asthma emergency department visits; and 8.2% increased risk for girls in hospitalizations. Among girls, we observed stronger associations among older children (10-13 and 14-17 year age groups). We did not observe significant modification by age for boys. Boys exhibited a more prompt response (lag day 1) to ozone than did girls (lag day 3), but significant associations for girls were retained longer, through lag day 6.

CONCLUSIONS

Our study indicates significant variance in associations between short-term ozone concentrations and asthma events by child sex and age. Differences in ozone response for boys and girls, before and after puberty, may point towards both social (gendered) and biological (sex-linked) sources of effect modification.

Ethnicity and acculturation: do they predict weight status in a longitudinal study among Asian, Hispanic, and non-Hispanic White early adolescent females?

Background

The prevalence of overweight and obesity among adolescents has increased over the past decade. Prevalence rates are disparate among certain racial and ethnic groups. This study sought to longitudinally examine the relationship between overweight status (≥85th percentile according to the Centers for Disease Control and Prevention growth charts) and ethnic group, as well as acculturation (generation and language spoken in the home) in a sample of adolescent females.

Methods

Asian (n=160), Hispanic (n=217), and non-Hispanic White (n=304) early adolescent girls participating in the multistate calcium intervention study with complete information on weight, ethnicity, and acculturation were included. Multiple methods of assessing longitudinal relationships (binary logistic regression model, linear regression model, Cox proportional-hazards regression analysis, and Kaplan–Meier survival analysis) were used to examine the relationship.

Results

The total proportion of girls overweight at baseline was 36%. When examining by ethnic group, the proportion varied with Hispanic girls having the highest percentage (46%) in comparison to their Asian (23%) and Non-Hispanic White (35%) counterparts. Although the total proportion of overweight was 36% at 18 months, the variation across the ethnic groups remained with the proportion of Hispanic girls becoming overweight (55%) being greater than their Asian (18%) and non-Hispanic White (34%) counterparts. However, regardless of the statistical approach used, there were no significant associations between overweight status and acculturation over time.

Conclusion

These unexpected results warrant further exploration into factors associated with overweight, especially among Hispanic girls, and further investigation of acculturation’s role is warranted. Identifying these risk factors will be important for developing targeted obesity prevention initiatives.

Menstruation in adolescents: what do we know? And what do we do with the information?

The menstrual cycle has been recognized as a vital sign that gives information about the overall health of an adolescent or young adult female. Significant deviations from monthly cycles can signal disease or dysfunction. This review highlights the evidence based parameters for normal puberty, menarche, cyclicity, and amount of bleeding. The review addresses sources of information available online, noting inaccuracies that appear in web sites, even and especially those targeting adolescents. The review includes a call to action to provide accurate information about the menstrual cycle as a VITAL SIGN.

Adiposity, chronic inflammation, and the prepubertal decline of sex hormone binding globulin in children: evidence for associations with the timing of puberty (Earlybird 58)

BACKGROUND

The regulation and role of SHBG in children are poorly defined. Here we investigated whether adiposity-related mechanisms regulate SHBG and whether SHBG levels are associated with the age of puberty.

METHODS

Longitudinal modelling of annual physiological and endocrine measurements from age 5 to 15 years in a cohort of 347 Plymouth schoolchildren.

RESULTS

SHBG levels were highest at age 5 years and then declined. Mean (SE) SHBG levels were higher in boys than girls at age 5 years [mean (SE) difference 7.68 (3.80) nmol/L; P = .045] but lower in boys by age 15 years [difference 12.19 (3.4) nmol/L; P < .001]. SHBG correlated inversely with adiposity [body mass index SD score (BMI SDS)], insulin, IGF-I, C-reactive protein (CRP), and leptin and positively with adiponectin but not with dehydroepiandrosterone sulphate, androstenedione, or T. In linear mixed models, five adiposity-related covariates (insulin, leptin, adiponectin, IGF-I, and CRP) all exerted significant main effects on SHBG (boys P = .04 to < .001; girls P = .007 to < .001). However, the further addition of BMI SDS rendered the effects of leptin, insulin, and adiponectin nonsignificant, whereas CRP and IGF-I remained significant. In separate models, the individual effects on SHBG of insulin, leptin, IGF-I, and adiponectin, but not CRP, were displaced by BMI SDS. Finally, in linear regression, BMI SDS little affected R(2) resulting from the five adiposity-related signals. Girls with lower SHBG levels at age 5 years reached Tanner stage 2 earlier, tended to have earlier LH secretion, and earlier age at peak height velocity and menarche. In contrast, boys with lower SHBG levels at age 5 years reached Tanner stage 2 earlier, but there were no relationships between SHBG and earlier onset of LH secretion or age at peak height velocity.

CONCLUSIONS

Adiposity-related endocrine mechanisms and chronic inflammation were associated with the prepubertal decline of SHBG, and lower SHBG levels anticipated earlier puberty. These findings may be relevant to the occurrence of earlier puberty in recent decades.

CYP19A1 promoter methylation in saliva associated with milestones of pubertal timing in urban girls

Background

Childhood obesity and early puberty are intermediate risk factors for later metabolic and reproductive disorders including diabetes, polycystic ovarian syndrome (PCOS), and breast cancer. Atypical methylation patterns in genes related to hormone and adipose metabolism, such as CYP19A1 (aromatase) and PPARG (peroxisome proliferator-activated receptor gamma), are associated with alterations in gene expression which may contribute to pathogenesis of these diseases. If present in early life, it is conceivable similar methylation aberrations may result in hormone perturbations that alter pubertal timing.

Methods

We used Cox proportional hazard models to investigate whether promoter methylation of CYP19A1 and PPARG, independently or in concert with body weight, was associated with age at breast (B2) or pubic hair development (PH2) when assayed in saliva DNA collected from a cohort of New York City, Black and Hispanic girls (N = 130) enrolled in a study of pubertal timing between 6–8 years of age.

Results

An inverse association between CYP19A1 methylation and risk of early PH2 was suggested (HR = 0.95, 95% CI = 0.90-1.00, p = 0.05). CYP19A1 methylation also appeared to modify risk of early B2 associated with body weight. Specifically, compared to normal weight girls with ‘high’ CYP19A1 methylation, significantly increased risk of early B2 was observed in overweight girls with ‘low’ but not ‘high’ CYP19A1 methylation (HR = 2.15; 95% CI = 1.23- 3.76). However, in formal tests for effect modification, the interaction between body weight and methylation did not reach statistical significance (p for interaction = 0.085). PPARG methylation was not significantly associated with PH2 or B2.

Conclusions

Though limited by sample size, our findings suggest methylation of CYP19A1, a critical gene in estrogen biosynthesis, may influence timing of breast development in overweight girls. Consistent with emerging reports, these data support the notion that epigenetic marks in surrogate tissues may improve risk prediction when added to standard plasma and anthropometric indicators, and warrant further study.

Early neuroendocrine disruption in hypothalamus and hippocampus: developmental effects including female sexual maturation and implications for endocrine disrupting chemical screening

The timing of puberty has been mainly studied in females for several reasons, including the possible evaluation of a precise timer (i.e. menarcheal age) and concerns with respect to the high prevalence of precocity in females as opposed to males. Human evidence of altered female pubertal timing after exposure to endocrine disrupting chemicals (EDCs) is equivocal. Among the limiting factors, most studies evaluate exposure to single EDCs at the time of puberty and hardly assess the impact of lifelong exposure to mixtures of EDCs. Some rodent and ovine studies indicate a possible role of foetal and neonatal exposure to EDCs, in accordance with the concept of an early origin of health and disease. Such effects possibly involve neuroendocrine mechanisms because the hypothalamus is a site where homeostasis of reproduction, as well as control of energy balance, is programmed and regulated. In our previous studies, pulsatile gonadotrophin-releasing hormone (GnRH) secretion control via oestrogen, glutamate and aryl hydrocarbon receptors was shown to be involved in the mechanism of sexual precocity after early postnatal exposure to the insecticide dichlorodiphenyltrichloroethane. Very recently, we have shown that neonatal exposure to the potent synthetic oestrogen diethylstilbestrol (DES) is followed by early or delayed puberty depending on the dose, with consistent changes in developmental increase of GnRH pulse frequency. Moreover, DES results in reduced leptin stimulation of GnRH secretion in vitro, an effect that is additive with prenatal food restriction. Thus, using puberty as an endpoint of the effects of EDC, it appears necessary to consider pre- and perinatal exposure to low doses and to pay attention to the other conditions of prenatal life, such as energy availability, keeping in mind the possibility that puberty could not only be advanced, but also delayed through neuroendocrine mechanisms.

Sexual precocity and its treatment

BACKGROUND

Puberty is a complex and dynamic period in development during which individuals transition from the juvenile to adult state. Regulated by multiple genetic and endocrine controls, it is characterized by somatic growth and sexual maturation. Sexual precocity is defined as the appearance of secondary sexual characteristics before the lower limit of the normal age for pubertal onset.

DATA SOURCES

Based on recent publications and the experience with the disease of our group, we reviewed the normal timing and order of puberty, the definition of sexual precocity, the classification of sexual precocity, the differential diagnosis of sexual precocity, variations in pubertal development, the diagnosis of sexual precocity, and the treatment of sexual precocity.

RESULTS

Sexual precocity can be classified as either gonadotropin-releasing hormone (GnRH)-dependent or GnRH-independent. Regardless of the etiology, sexual precocity causes increased height velocity, somatic development, and skeletal maturation, which may have profound physical and psychological implications.

CONCLUSIONS

The treatment of sexual precocity is focused on its cause and must address both its psychosocial and clinical implications. For GnRH-dependent precocious puberty, GnRH agonists are the main pharmacological agents used. Alternatively, the treatment of disorders causing GnRH-independent sexual precocity is directed toward the underlying abnormality.

Male pubertal development: are endocrine-disrupting compounds shifting the norms?

Endocrine-disrupting compounds (EDCs) are synthetic or natural compounds that interfere with endogenous endocrine action. The frequent use of chemicals with endocrine active properties in household products and contamination of soil, water, and food sources by persistent chemical pollutants result in ubiquitous exposures. Wildlife observations and animal toxicological studies reveal adverse effects of EDCs on reproductive health. In humans, a growing number of epidemiological studies report an association with altered pubertal timing and progression. While these data are primarily reported in females, this review will focus on the small number of studies performed in males that report an association of polychlorinated biphenyls with earlier sexual maturity rating and confirm subtle effects of lead, dioxins, and endosulfan on delaying pubertal onset and progression in boys. Recent studies have also demonstrated that EDC exposure may affect pubertal testosterone production without having a noticeable effect on sexual maturity rating. A limitation to understand the effects of EDCs in humans is the potential for confounding due to the long temporal lag from early-life exposures to adult outcomes. The complex interplay of multiple environmental exposures over time also complicates the interpretation of human studies. These studies have identified critical windows of vulnerability during development when exposures to EDCs alter critical pathways and affect postnatal reproductive health. Contemporaneous exposures can also disrupt the hypothalamic-pituitary-gonadal axis. This paper will review the normal process of puberty in males and summarize human data that suggest potential perturbations in pubertal onset and tempo with early-life exposures to EDCs.

Neural systems supporting cognitive-affective interactions in adolescence: the role of puberty and implications for affective disorders

Evidence from longitudinal studies suggests that adolescence may represent a period of vulnerability that, in the context of adverse events, could contribute to developmental trajectories toward behavioral and emotional health problems, including affective disorders. Adolescence is also a sensitive period for the development of neural systems supporting cognitive-affective processes, which have been implicated in the pathophysiology of affective disorders such as anxiety and mood disorders. In particular, the onset of puberty brings about a cascade of physical, hormonal, psychological, and social changes that contribute in complex ways to the development of these systems. This article provides a brief overview of neuroimaging research pertaining to the development of cognitive-affective processes in adolescence. It also includes a brief review of evidence from animal and human neuroimaging studies suggesting that sex steroids influence the connectivity between prefrontal cortical and subcortical limbic regions in ways that contribute to increased reactivity to emotionally salient stimuli. We integrate these findings in the context of a developmental affective neuroscience framework suggesting that the impact of rising levels of sex steroids during puberty on fronto-limbic connectivity may be even greater in the context of protracted development of prefrontal cortical regions in adolescence. We conclude by discussing the implications of these findings for future research aimed at identifying neurodevelopmental markers of risk for future onset of affective disorders.