Influences on the onset and tempo of puberty in human beings and implications for adolescent psychological development (original) (raw)
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Trends in puberty timing in humans and environmental modifiers
Molecular and Cellular Endocrinology, 2010
Secular trends in timing of puberty appear to continue although under-nutrition has not been any longer a limiting factor for pubertal development. Now obesity and other environmental reasons have been suspected to cause this trend, and endocrine disrupting chemicals have become into focus as possible contributors. Epidemiological studies on endocrine disrupters are still scarce and show only weak associations between exposures and timing of puberty. Since genetic background explains 50-80% of variability in the timing of puberty, it is not surprising that the observed environmental effects are rather modest when individual exposures are assessed. Despite that, some exposures have been reported to be associated to early (e.g., polybrominated biphenyls) or delayed (e.g., lead) puberty. Here we shortly review the available data on recent trends in timing of puberty and the possible role of endocrine disrupters.
Role of Environmental Factors in the Timing of Puberty
PEDIATRICS, 2008
Puberty-timing measures have historically been used as indicators of adequate nutrition and growth. More recently, these measures have been examined in relation to exposure to estrogenic or antiandrogenic agents, as well as other environmental factors. The scientific community has debated whether puberty timing is occurring earlier today than in the mid-1900s in the United States and, if so, whether environmental factors play a role; however, no one has asked a multidisciplinary panel to resolve this question. Thus, a multidisciplinary expert panel jointly sponsored by the US Environmental Protection Agency, the National Institute of Environmental Health Sciences, and Serono Symposia International was convened to examine the evidence of a secular trend, identify potential environmental factors of concern, and identify research needs regarding environmental factors and puberty timing at "The Role of Environmental Factors on the Timing and Progression of Puberty" workshop. The majority of the panelists concluded that the girls' data are sufficient to suggest a secular trend toward earlier breast development onset and menarche from 1940 to 1994 but that the boys' data are insufficient to suggest a trend during this same period. The weight-of-the-evidence evaluation of human and animal studies suggest that endocrine-disrupting chemicals, particularly the estrogen mimics and antiandrogens, and body fat are important factors associated in altered puberty timing. A change in the timing of puberty markers was considered adverse from a public health perspective. The panel recommended research areas to further our understanding of the relationships among environmental factors, puberty-timing outcomes, and other reproductive and adult disease at the individual and population levels.
Puberty in Girls of the 21st Century
Journal of Pediatric and Adolescent Gynecology, 2012
Several studies have noted contemporary girls are undergoing pubertal maturation at younger ages. During this same time period many Western nations have experienced an obesity epidemic, prompting investigators and public health officials to consider the association of these two events, and if other exposures might impact this relationship. There are several potential mechanisms that could impact the relationship of pubertal timing in girls with greater body mass, including direct effects of obesity on pubertal timing as well underlying exposures that impact body mass as well as timing of pubertal maturation. These underlying conditions include chemical compounds that could impact synthesis or action of sex hormones, called endocrine disrupting chemicals (EDs). This paper will examine the decline in the age of breast development and potential genetic and environmental influences, the obesity epidemic in the US and other nations, and potential mechanisms to explain the relationship between greater body mass index with earlier puberty in girls.
Environmental Factors and Puberty Onset: An Update
Journal of Biology and Life Science, 2014
Puberty is a process that results from a coordinated series of complex neuroendocrine changes which eventually leads to external and internal physical changes. These changes include attainment of primary and secondary sexual characteristics. Puberty as a temporal process is subdivided into different stages. These pubertal stages occur in a sequential manner but significant variations have been seen among different individuals in the timings of pubertal onset as well as a certain degree of gender difference is also present where puberty is occurring 166 earlier in girls than boys. Among many aetiologies which have been hypothesized to be involved, environmental cues are the most ones. This review article describes the recent findings of the influences of the key environmental clues on pubertal timings, emphasizing on the aspects for which the most scientific evidences exist.
The missing politics and unsettled science of the trend toward earlier puberty
Politics and the life sciences : the journal of the Association for Politics and the Life Sciences, 2001
The age of puberty in many populations has declined steeply over recent centuries and may be declining still. Consequently, today's children tend to experience the hormonal stresses of rapid development at younger ages than did their ancestors, around whose later, if not more gradual, maturation traditional behavioral expectations formed. Little has been made of this "rush to puberty" outside the life sciences. This article reviews its historical documentation, scholarly appreciation, epidemiological correlations, putative physiological and environmental explanations, sociological implications, and largely latent politics.
American Journal of Clinical Nutrition, 2009
Background: Early age at puberty onset may predispose an individual to many currently prevalent diseases, including cancer and adiposity. Objective: The objective was to investigate whether early life exposures influence the timing of puberty, as defined by both early and late markers, in healthy German girls and boys. Design: Term participants (n = 215; 49.8% female) of the DONALD (DOrtmund Nutritional and Anthropometric Longitudinally Designed) Study, with sufficient repeated anthropometric measurements between 6 and 13 y to allow estimation of age at take-off of the pubertal growth spurt (ATO) and information on a variety of early life exposures, including birth weight, breastfeeding status, velocity of weight gain, and parental characteristics, were studied. Age at peak height velocity (APHV) and menarche were also considered. Results: Children who weighed between 2500 and ,3000 g at birth were '7 mo younger at ATO than were the other children (b 6 SE: 20.56 6 0.20 y; P = 0.006). Children who had gained weight rapidly between birth and 24 mo (increase in weight SD score .0.67) experienced ATO 4 mo earlier than those who had gained weight normally (20.34 6 0.15 y; P = 0.02). Rapid weight gain was also associated with an earlier APHV (P = 0.0006) and, in girls, with an earlier menarche (P = 0.002). Adjustment for body mass index SD score or body fat percentage 1, 2, or 3 y before ATO did not account for these effects. Conclusion: In both boys and girls, intrauterine and early postnatal growth factors appear to influence both early and later markers of puberty onset independently of prepubertal body composition.
Public Health Implications of Altered Puberty Timing
PEDIATRICS, 2008
Changes in puberty timing have implications for the treatment of individual children, for the risk of later adult disease, and for chemical testing and risk assessment for the population. Children with early puberty are at a risk for accelerated skeletal maturation and short adult height, early sexual debut, potential sexual abuse, and psychosocial difficulties. Altered puberty timing is also of concern for the development of reproductive tract cancers later in life. For example, an early age of menarche is a risk factor for breast cancer. A low age at male puberty is associated with an increased risk for testicular cancer according to several, but not all, epidemiologic studies. Girls and, possibly, boys who exhibit premature adrenarche are at a higher risk for developing features of metabolic syndrome, including obesity, type 2 diabetes, and cardiovascular disease later in adulthood. Altered timing of puberty also has implications for behavioral disorders. For example, an early maturation is associated with a greater incidence of conduct and behavior disorders during adolescence. Finally, altered puberty timing is considered an adverse effect in reproductive toxicity risk assessment for chemicals. Recent US legislation has mandated improved chemical testing approaches for protecting children's health and screening for endocrinedisrupting agents, which has led to changes in the US Environmental Protection Agency's risk assessment and toxicity testing guidelines to include puberty-related assessments and to the validation of pubertal male and female rat assays for endocrine screening.
Frontiers in Pediatrics, 2019
Puberty is a sensitive period of life characterized by the appearance of secondary sex characteristics which leads to a complete sexual maturation. It physiologically starts between the age of 8 and 13 years in girls and 9 and 14 years in boys. In the last two decades, several studies have showed that start of puberty has moved up to younger ages by 12-18 months, and some of the hypotheses trying to explain this change include the role of nutritional status and obesity and the influence of extrinsic factors such as exposure to endocrine-disrupting chemicals (EDCs), as well. The hypothalamic-hypophysis-gonadal axis develops during embryogenesis, and except for a period of activation immediately after birth, remains suppressed until the onset of pubertal development. At the beginning of puberty, the pulse generator is reactivated, probably due to progressive stimulatory influences on GnRH neurons from glial signals and neurotrasmitters. Kisspeptin and its receptor play a fundamental role in this phase. Premature Pubarche/Adrenarche, Premature Thelarche, and Premature Menarche are incomplete forms of precocious pubertal development that have their origin in endocrine mechanisms that only recently have started to be understood. It is important to distinguish these forms from the complete ones in order to reassure patients and parents about the non-evolution of pubertal progression and avoid non-useful treatments with analogous LHRH.
Beyond overweight: nutrition as an important lifestyle factor influencing timing of puberty
Nutrition Reviews, 2012
Early onset of puberty may confer adverse health consequences. Thus, modifiable factors influencing the timing of puberty are of public health interest. Childhood overweight as a factor in the earlier onset of menarche has been supported by prospective evidence; nonetheless, its overall contribution may have been overemphasized, since secular trends toward a younger age at menarche have not been a universal finding during the recent obesity epidemic. Current observational studies suggest notable associations between dietary intakes and pubertal timing beyond contributions to an energy imbalance: children with the highest intakes of vegetable protein or animal protein experience pubertal onset up to 7 months later or 7 months earlier, respectively. Furthermore, girls with high isoflavone intakes may experience the onset of breast development and peak height velocity approximately 7-8 months later. These effect sizes are on the order of those observed for potentially neuroactive steroid hormones. Thus, dietary patterns characterized by higher intakes of vegetable protein and isoflavones and lower intakes of animal protein may contribute to a lower risk of breast cancer or a lower total mortality.