The effect of wartime conditions and the 1944-45 'Dutch famine' on recalled menarcheal age in participants of the DOM breast cancer screening project

Coming of age in war: Early life adversity, age at menarche, and mental health

Armed conflict and forced migration (ACFM) represent a set of extreme environments that are increasingly common for children and adolescents to experience. Adolescence may constitute a sensitive period (puberty and psychoneurological maturation) through which ACFM adversity leaves a lasting mark. Adolescence has become a focal point for analysis and intervention as it relates to the effects of early life adversity on puberty, linear growth, and mental health. Research in public health and psychological science suggests early life adversity (ELA) may accelerate puberty, heightening risks for mental health disorders. However, it is not well substantiated whether ACFM-derived adversities accelerate or delay relative pubertal timing. Secondly, ACFM provides salient context through which to probe the relationships between nutritional, psychosocial, and demographic changes and their respective impact on puberty and mental health. We conducted a narrative review which 1) examined constructions of early life adversity and their proposed influence on puberty 2) reviewed empirical findings (n = 29 studies, n = 36 samples) concerning effects of ACFM ELA on age at menarche and 3) discussed proposed relationships between early life adversity, puberty, and mental ill-health. Contrary to prior research, we found war-derived early life adversity was more consistently associated with pubertal delay than acceleration and may exert counterintuitive effects on mental health. We show that ELA cannot be operationalized in the same way across contexts and populations, especially in the presence of extreme forms of human stress and resilience. We further discuss the ethics of puberty research among conflict-affected youth.

Trends in age at menarche from 1943 through 1989 in Taiwan: A retrospective population-based analysis

BACKGROUND

Recent studies have demonstrated a global decline in the age at menarche. Our study aimed to determine the age at menarche of Taiwanese women born between 1943 and 1989.

METHODS

Data were obtained from the Taiwan Biobank. To view the trends in age at menarche, we analyzed data from 74,799 women. The mean, standard deviation, and annual percentage change in age at menarche were calculated for birth-year cohorts.

RESULTS

The mean age at menarche of Taiwanese women born in 1943 was 14.85 years. The age at menarche decreased to 12.20 years for those born in 1989. The mean age at menarche declined by 2.65 years across the 47-year study period; hence, the reduction rate was 0.56 years per decade. This study demonstrated a downward secular trend in the age at menarche of Taiwanese women born between 1943 and 1989. This trend occurred in three stages of decline: fast (1943-1953), slow (1953-1965), and moderate (1965-1989).

CONCLUSION

The age at menarche decreased by 2.65 years among Taiwanese women born in 1943 compared with those born in 1989. This decline occurred in three stages: fast (1943-1953), slow (1953-1965), and moderate (1965-1989). This significant downward secular trend in age at menarche reflects Taiwan's socioeconomic development.

Hierarchies in the energy budget: Thyroid hormones and the evolution of human life history patterns

The evolution of human life history characteristics required dramatic shifts in energy allocation mechanisms compared with our primate ancestors. Thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3), are sensitive to energy balance, and are significant determinants for both tissue-specific and whole-body metabolic rate. Thus, thyroid hormones are in part responsible for setting the body's overall energy budget and likely played an important role in the evolution of human life history patterns. We propose that the dynamics of mammalian T3 production, uptake, and action have evolved so that energy allocation prioritizes the high demands of brain development and functioning, often at the expense of growth and reproduction. This paper explores the role of thyroid hormone dynamics in the evolution of human encephalization, prolonged childhood and adolescence, long lifespans, reproduction, and human aging.

Associations between distinct dimensions of early life adversity and accelerated reproductive strategy among middle-aged women in China

BACKGROUND

Life history theory argues that unpredictable and harsh conditions such as early life adversity tends to produce a fast life history strategy, characterized by early sexual maturation and less parenting of offspring. It remains unclear whether all forms of early life adversity are associated with accelerated reproductive strategy, and most previous studies predominantly focused on single form of reproductive strategy indicators.

OBJECTIVE

To examine the associations between 2 distinct dimensions of early life adversity (ie, threat and deprivation) and reproductive strategies across global metrics.

STUDY DESIGN

We used data from 9674 middle-aged women of the China Health and Retirement Longitudinal Study. The experiences of threat and deprivation were assessed using the Life History Survey Questionnaire in 2014. Reproductive strategy information was assessed via self-report from the follow-up of 2013, 2015 and 2018, including age at menarche, age at natural menopause, age at first birth, total number of children, and number of abortions. Multivariate linear regression analyses were performed to assess the associations between distinct dimensions of early life adversity and multiple reproductive strategy indicators, adjusting for age, Hukou location, family socioeconomic status in adulthood and body mass index.

RESULTS

Of the 9674 women (mean [standard deviation] age at baseline, 55.89 [10.23] years), 4084 (42.20%) reported exposure to threat-related early life adversity and 7332 (75.79%) reported exposure to deprivation-related early life adversity. Early life adversity characterized by threat was associated with accelerated reproductive strategy. Compared with women who have no experiences of threat-related early life adversity, ≥3 threat-related early life adversity was associated with 3.7-month earlier age at menarche (β=-0.31, 95% confidence interval, -0.53 to -0.08; P=.007), 8.6-month earlier age at natural menopause (β=-0.72, 95% confidence interval, -1.29 to -0.15; P=.013), >1-year earlier age at first birth (β=-1.14, 95% confidence interval, -1.58 to -0.71; P<.0001), and an increased total number of children (β=0.25, 95% confidence interval, 0.10-0.41; P=.002). In contrast, experiences of deprivation were associated with delayed age at natural menopause (β=.50, 95% confidence interval, 0.06-0.94; P=.025) and increased number of abortions (β=.17, 95% confidence interval, 0.01-0.34, P=.037), in models adjusting for co-occurring threat exposures.

CONCLUSION

This study suggests that early life adversity characterized by threat was associated with accelerated reproductive strategy, whereas deprivation was associated with slower reproduction strategy. Future research should clarify the biological pathways between different dimensions of early life adversity and reproductive strategies and further determine whether accelerated reproduction is an adaptive response to early life adversity in humans.

Temporal trends in age at menarche and age at menopause: a population study of 312 656 women in Norway

STUDY QUESTION

Have mean age at menarche or mean age at natural menopause changed from the 1939 birth cohort to the 1964 birth cohort?

SUMMARY ANSWER

We estimated a minor decrease in mean age at menarche and an increase by nearly 3 years in mean age at natural menopause.

WHAT IS KNOWN ALREADY

In the Western world, age at menarche decreased across birth cohorts from the early 1800s until the 1950s. Whether mean age at menarche has continued to decrease in birth cohorts after the 1950s remains uncertain. It is also uncertain whether mean age at natural menopause has changed across birth cohorts.

STUDY DESIGN, SIZE, DURATION

We performed a retrospective population study of 312 656 women who were born in Norway during the years 1936–1964.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The data were obtained by two self-administered questionnaires from women who participated in the Norwegian breast cancer screening program (BreastScreen Norway) during the years 2006–2014. We used flexible parametric survival models with restricted cubic splines to estimate mean age at menarche, mean age at menopause and mean number of years between menarche and menopause according to the women’s year of birth. The women who were still having menstrual periods contributed with follow-up time until the time of data collection, and the women who had reported surgical removal of the uterus and/or both ovaries prior to natural menopause contributed with follow-up time until the time of surgery.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean age at menarche was 13.42 years (95% CI: 13.40–13.44 years) among women born during 1936–1939, and it was 13.24 years (95% CI: 13.22–13.25 years) among women born during 1960–1964. The mean age at natural menopause increased from 50.31 years (95% CI: 50.25–50.37 years) among women born during 1936–1939 to 52.73 years (95% CI: 52.64–52.82 years) among women born during 1960–1964. The mean number of years between menarche and menopause increased from 36.83 years (95% CI: 36.77–36.89 years) to 40.22 years (95% CI: 40.11–40.34 years).

LIMITATIONS, REASONS FOR CAUTION

Information about age at menarche and age at menopause was based on self-reports.

WIDER IMPLICATIONS OF THE FINDINGS

Late menopause is associated with increased risk of breast cancer but also with increased life expectancy. Thus, higher mean age at menopause may partly explain the increase in breast cancer incidence after menopause and the increase in life expectancy in recent time. Also, a longer interval between menarche and menopause could suggest that the number of years of female fecundity has increased.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the South-Eastern Norway Regional Health Authority [grant number 2016112 to M.S.G.] and by the Norwegian Cancer Society [grant number 6863294-2015 to E.K.B.]. The authors declare no conflicts of interest.

Biological aging in childhood and adolescence following experiences of threat and deprivation: A systematic review and meta-analysis

Life history theory argues that exposure to early life adversity (ELA) accelerates development, although existing evidence for this varies. We present a meta-analysis and systematic review testing the hypothesis that ELA involving threat (e.g., violence exposure) will be associated with accelerated biological aging across multiple metrics, whereas exposure to deprivation (e.g., neglect, institutional rearing) and low-socioeconomic status (SES) will not. We meta-analyze 54 studies (n = 116,010) examining associations of ELA with pubertal timing and cellular aging (telomere length and DNA methylation age), systematically review 25 studies (n = 3,253) examining ELA and neural markers of accelerated development (cortical thickness and amygdala-prefrontal cortex functional connectivity) and evaluate whether associations of ELA with biological aging vary according to the nature of adversity experienced. ELA overall was associated with accelerated pubertal timing (d = -0.10) and cellular aging (d = -0.21), but these associations varied by adversity type. Moderator analysis revealed that ELA characterized by threat was associated with accelerated pubertal development (d = -0.26) and accelerated cellular aging (d = -0.43), but deprivation and SES were unrelated to accelerated development. Systematic review revealed associations between ELA and accelerated cortical thinning, with threat-related ELA consistently associated with thinning in ventromedial prefrontal cortex, and deprivation and SES associated with thinning in frontoparietal, default, and visual networks. There was no consistent association of ELA with amygdala-PFC connectivity. These findings suggest specificity in the types of early environmental experiences associated with accelerated biological aging and highlight the importance of evaluating how accelerated aging contributes to health disparities and whether this process can be mitigated through early intervention. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Earlier age at menarche as a transdiagnostic mechanism linking childhood trauma with multiple forms of psychopathology in adolescent girls

BACKGROUND

Although early life adversity (ELA) increases risk for psychopathology, mechanisms linking ELA with the onset of psychopathology remain poorly understood. Conceptual models have argued that ELA accelerates development. It is unknown whether all forms of ELA are associated with accelerated development or whether early maturation is a potential mechanism linking ELA with psychopathology. We examine whether two distinct dimensions of ELA - threat and deprivation - have differential associations with pubertal timing in girls, and evaluate whether accelerated pubertal timing is a mechanism linking ELA with the onset of adolescent psychopathology.

METHODS

Data were drawn from a large, nationally representative sample of 4937 adolescent girls. Multiple forms of ELA characterized by threat and deprivation were assessed along with age at menarche (AAM) and the onset of DSM-IV fear, distress, externalizing, and eating disorders.

RESULTS

Greater exposure to threat was associated with earlier AAM (B = -0.1, p = 0.001). Each 1-year increase in AAM was associated with reduced odds of fear, distress, and externalizing disorders post-menarche (ORs = 0.74-0.85). Earlier AAM significantly mediated the association between exposure to threat and post-menarche onset of distress (proportion mediated = 6.2%), fear (proportion mediated = 16.3%), and externalizing disorders (proportion mediated = 2.9%).

CONCLUSIONS

Accelerated pubertal development in girls may be one transdiagnostic pathway through which threat-related experiences confer risk for the adolescent onset of mental disorders. Early pubertal maturation is a marker that could be used in both medical and mental health settings to identify trauma-exposed youth that are at risk for developing a mental disorder during adolescence in order to better target early interventions.

Investigation of sirtuin 1 polymorphisms in relation to the risk of colorectal cancer by molecular subtype

Sirtuin 1 (SIRT1), a histone deacetylase, is involved in maintenance of genetic stability, inflammation, immune response, metabolism (energy-sensing molecule) and colorectal tumorigenesis. We investigated SIRT1's specific role in colorectal tumorigenesis by studying SIRT1 polymorphisms in relation to colorectal cancer (CRC) risk by microsatellite instability (MSI) and CpG island methylator phenotype (CIMP) status. The Netherlands Cohort study (NLCS) was initiated in 1986 and includes 120,852 participants in a case-cohort design. CRC tumour samples were available for incident cases between 1989 and 1993. Toenail deoxyribonucleic acid (DNA) was used for genotyping of two SIRT1 tagging variants (rs10997870 and rs12778366). Excluding the first 2.3 years of follow-up, subcohort members and CRC cases with no toenail DNA available and those with low sample call rates, and CRC cases with no tumour DNA available left 3478 subcohort members and 533 CRC cases. Cox regression was utilised to estimate hazard ratios (HRs) for MSI and CIMP positive and negative tumours by SIRT1 genotypes. The results were that the rs12778366 TC/CC versus TT genotype was inversely associated with MSI CRC (HR = 0.41, 95% confidence interval: 0.20, 0.88), while no association was found with the risk of an MSS tumour (TC/CC versus TT carriers: HR = 1.13, 95% CI: 0.89, 1.44). No significant associations were found between other SIRT1 genotypes and CRC subtypes. In conclusion, the results suggest a role for SIRT1 polymorphisms in colorectal tumorigenesis, particularly MSI CRC.

The Embodiment of War: Growth, Development, and Armed Conflict

Armed conflict regularly presents extremely adverse circumstances not only for combatants, but also for civilians. In fact, estimates from various wars over the past 70 years suggest that noncombatants comprise the majority of casualties. For survivors, war's effects are often embodied, leaving long-term effects on health and biology. Some of these effects, such as injuries and psychological trauma, are well known. Yet other effects may be subtle and may be elucidated by a developmental biological perspective. In early life, when growth rates are highest, conditions of war may have their greatest impact. Depending on local circumstances, a developing embryo, infant, or child growing in a place embroiled in armed conflict is likely to face—directly or indirectly—various stressors, including malnutrition, infectious disease, and/or psychological stress. Thus, the conditions of war and forced displacement may become embodied, getting under the skin for fundamental biological reasons.

Contribution of the Endocrine Perspective in the Evaluation of Endocrine Disrupting Chemical Effects: The Case Study of Pubertal Timing

Debate makes science progress. In the field of endocrine disruption, endocrinology has brought up findings that substantiate a specific perspective on the definition of endocrine disrupting chemicals (EDCs), the role of the endocrine system and the endpoints of hormone and EDC actions among other issues. This paper aims at discussing the relevance of the endocrine perspective with regard to EDC effects on pubertal timing. Puberty involves particular sensitivity to environmental conditions. Reports about the advancing onset of puberty in several countries have led to the hypothesis that the increasing burden of EDCs could be an explanation. In fact, pubertal timing currently shows complex changes since advancement of some manifestations of puberty (e.g. breast development) and no change or delay of others (e.g. menarche, pubic hair development) can be observed. In a human setting with exposure to low doses of tenths or hundreds of chemicals since prenatal life, causation is most difficult to demonstrate and justifies a translational approach using animal models. Studies in rodents indicate an exquisite sensitivity of neuroendocrine endpoints to EDCs. Altogether, the data from both human and animal studies support the importance of concepts derived from endocrinology in the evaluation of EDC effects on puberty.

Preterm birth and the timing of puberty: a systematic review

BACKGROUND

An estimated 11% of births occur preterm, and survival is improving. Early studies suggested an association between preterm birth and earlier puberty. Given the adverse outcomes associated with early puberty this could have significant public health implications. The objective of this review was to assess the timing of puberty after preterm birth.

METHODS

Pubmed, Embase, Popline, Global Health and Global Health Library were searched using terms relating to "premature birth", "menarche", "puberty" and "follow up studies". Inclusion criteria were a population consisting of pubertal or post-pubertal adolescents and adults; studies which defined preterm delivery in participants and compared outcomes to those after term delivery; and a quantitative assessment of pubertal onset. Assessment of risk of bias was conducted using principles from the Critical Appraisal Study Process.

RESULTS

Our search identified 1051 studies, of which 16 met the inclusion criteria. In females, 8 studies found no association between preterm birth and the timing of menarche. Five studies found earlier onset in preterm infants, 1 found later onset, and 1 showed both earlier and later menarche, depending on birth weight. The range of effect of studies showing earlier menarche was - 0.94 to -0.07 years in the preterm group, with a median of - 0.3 years. In males, 2 studies showed earlier onset of puberty in the preterm group, 5 showed no difference, and 1 showed later onset. Most studies did not present outcomes in the form of a mean with standard deviation, precluding a meta-analysis. There was insufficient data to address potential confounding factors.

CONCLUSIONS

The published evidence does not suggest that being born preterm leads to a significant acceleration in the onset of puberty. This should prove reassuring for public health purposes, and for clinicians counseling parents of infants born preterm.

Early puberty in 11-year-old girls: Millennium Cohort Study findings

OBJECTIVE

Early puberty in girls is linked to some adverse outcomes in adolescence and mid-life. We address two research questions: (1) Are socioeconomic circumstances and ethnicity associated with early onset puberty? (2) Are adiposity and/or psychosocial stress associated with observed associations?

DESIGN

Longitudinal data on 5839 girls from the UK Millennium Cohort Study were used to estimate associations between ethnicity, family income, adiposity and psychosocial stress with a marker of puberty.

MAIN OUTCOME MEASURE

Reported menstruation at age 11 years.

RESULTS

All quoted ORs are statistically significant. Girls in the poorest income quintile were twice as likely (OR=2.1), and the second poorest quintile nearly twice as likely (OR=1.9) to have begun menstruation compared with girls in the richest income quintile. Estimates were roughly halved on adjustment for Body Mass Index and markers of psychosocial stress (poorest, OR=1.5; second poorest, OR=1.5). Indian girls were over 3 times as likely compared with whites to have started menstruation (OR=3.5) and statistical adjustments did not attenuate estimates. The raised odds of menstruation for Pakistani (OR=1.9), Bangladeshi (OR=3.3) and black African (OR=3.0) girls were attenuated to varying extents, from about a third to a half, on adjustment for income and adiposity.

CONCLUSIONS

In contemporary UK, excess adiposity and psychosocial stress were associated with social inequalities in early puberty, while material disadvantage and adiposity were linked to ethnic inequalities in early puberty among girls.

Improvement in the biological standard of living in 20th century Korea: Evidence from age at menarche

OBJECTIVES

We used age at menarche to understand improvement in the biological standard of living in South Korea during the 20th century.

METHODS

The main dataset, the Korean National Health and Nutrition Examination Survey, provided a consistent source of nationally representative data with a large number of observations over a long period of time. We calculated mean ages at menarche by birth year and estimated the rate of decrease in age at menarche, while avoiding survival bias.

RESULTS

The mean age at menarche decreased from 16.64 for the birth year 1941 to 12.68 for the birth year 1992, decreasing 0.78 (or 0.81 in a regression) years per decade for the period. Comparisons with other populations demonstrate that this is the fastest rate of decline ever known. In contrast to other developed countries, the decreasing rate in Korea does not appear to slow. We also compared the trend in age at menarche to that of height and found that the rate of increase in height is also the fastest in history.

CONCLUSIONS

Age at menarche is an appropriate index of change in the general standard of living in South Korea over the 20th century. Am. J. Hum. Biol. 29:e22882, 2017. © 2016 Wiley Periodicals, Inc.

Developmental variations in environmental influences including endocrine disruptors on pubertal timing and neuroendocrine control: Revision of human observations and mechanistic insight from rodents

Puberty presents remarkable individual differences in timing reaching over 5 years in humans. We put emphasis on the two edges of the age distribution of pubertal signs in humans and point to an extended distribution towards earliness for initial pubertal stages and towards lateness for final pubertal stages. Such distortion of distribution is a recent phenomenon. This suggests changing environmental influences including the possible role of nutrition, stress and endocrine disruptors. Our ability to assess neuroendocrine effects and mechanisms is very limited in humans. Using the rodent as a model, we examine the impact of environmental factors on the individual variations in pubertal timing and the possible underlying mechanisms. The capacity of environmental factors to shape functioning of the neuroendocrine system is thought to be maximal during fetal and early postnatal life and possibly less important when approaching the time of onset of puberty.

Temporal trends of main reproductive characteristics in ten urban and rural regions of China: the China Kadoorie biobank study of 300 000 women

BACKGROUND

Chinese women's reproductive patterns have changed significantly over the past several decades. However, relatively little is known about the pace and characteristics of these changes either overall or by region and socioeconomic status.

METHODS

We examined the cross-sectional data from the China Kadoorie Biobank cohort study that recruited 300 000 women born between 1930 and 1974 (mean age: 51 years) from 10 socially diverse urban and rural regions of China. Temporal trends in several self-reported reproductive characteristics, and effect modification of these trends by area and education (as a surrogate for socioeconomic status), were examined.

RESULTS

The overall mean age at menarche was 15.4 (standard deviation 1.9) years, but decreased steadily over the 45 birth cohorts from 16.1 to 14.3 years, except for an anomalous increase of ∼1 year for women exposed to the 1958-61 famine in early adolescence. Similarly large changes were seen for other characteristics: mean parity fell (urban: 4.9 to 1.1; rural: 5.9 to 1.4); mean age at first birth increased (urban: 19.0 to 25.9 years; rural: 18.3 to 23.8 years); and birth spacing increased after 1980 to over 5 years. Breastfeeding declined after 1950 in urban and, after 1980, in rural women; and 68% of urban and 48% of rural women experienced a terminated pregnancy. Mean age at menopause increased from 47.9 to 49.3 years.

CONCLUSIONS

There have been striking changes in reproductive factors over time and between areas among these Chinese women. Their effects on major chronic diseases should be investigated.

Childhood and adolescent exposures and the risk of endometriosis

BACKGROUND

Because endometriosis is diagnosed predominantly in young women, exposures occurring during childhood or adolescence may have a major impact on the disease. However, potential risk factors during this time period have received little attention. Our objective was to investigate relationships between childhood and adolescent exposures and the risk of endometriosis.

METHODS

E3N is a prospective cohort of 98,995 French women aged 40-65 at enrollment in 1990. Follow-up questionnaires were sent every 2-3 years. Using a nested case-control design, we computed odds ratios (ORs) and 95% confidence intervals using unconditional logistic regression models.

RESULTS

A total of 2684 endometriosis cases were reported as surgically ascertained among the 75,918 included women. There were inverse relationships of endometriosis risk with menarcheal age (test for trend, P < 0.0001) and with menstrual cycle length before 17 years of age (test for trend, P = 0.06), whereas menstrual cycle regularity before 17 years of age was not associated with risk. There were modest associations of endometriosis risk with exposure to pet animals (OR = 1.12 [95% confidence interval =1.02-1.22]) or living in a farm for 3 or more consecutive months during childhood (1.12 [1.02-1.24]), although with no link to any specific type of farm animal. In addition, there were positive linear associations between endometriosis risk and level of indoor exposure to passive smoking during childhood (up to 1.34 [1.09-1.64] with several hours exposure a day), experiencing food deprivation during World War II (1.34 [0.94-1.91]), and walking activity at 8-15 years of age (1.17 [1.05-1.31] for 5+ hours a week).

CONCLUSIONS

This large study suggests that some exposures during childhood or adolescence may influence the risk of endometriosis. Further research is needed to confirm and better understand these relationships.

Determinants of age at menarche and time to menstrual cycle regularity in the French E3N cohort

PURPOSE

Early menarche has been associated with a greater risk of several major chronic diseases. Although largely genetically determined, age at menarche also has been related to environmental and lifestyle factors.

METHODS

Using linear regression models, we explored simultaneously several pre- and postnatal factors as potential determinants of age at menarche and time to menstrual cycle regularity in 96,493 women participating, since 1990, in the French E3N prospective cohort.

RESULTS

Younger age at recruitment, greater father's income index, urban birth place, greater birth length, and larger body silhouette during childhood were associated with an earlier age at menarche (from -1.3 to -4.6 months, P(trend) < .0001) whereas greater family size, food deprivation during childhood, and greater birth weight resulted in a delayed menarche (from +1.5 months to +5.3 months, P(trend) < .0001). Father's income index, urban birth place, and prematurity predicted a shorter time to menstrual cycle regularity (from -1.1 to -1.9 months, P(trend) < .04), whereas birth cohort, larger body silhouette at menarche, and childhood exposure to passive smoking were associated with a longer time to menstrual cycle regularity (from +1.1 months to +8.6 months, P(trend) < .006).

CONCLUSIONS

Age at menarche and menstrual cycle regularity are significantly influenced by several individual, environmental and lifestyle factors.

Insights into the beneficial effect of caloric/ dietary restriction for a healthy and prolonged life

Over the last several years, new evidence has kept pouring in about the remarkable effect of caloric restriction (CR) on the conspicuous bedfellows- aging and cancer. Through the use of various animal models, it is now well established that by reducing calorie intake one can not only increase life span but, also, lower the risk of various age related diseases such as cancer. Cancer cells are believed to be more dependent on glycolysis for their energy requirements than normal cells and, therefore, can be easily targeted by alteration in the energy-metabolic pathways, a hallmark of CR. Apart from inhibiting the growth of transplantable tumors, CR has been also shown to inhibit the development of spontaneous, radiation, and chemically induced tumors. The question regarding the potentiality of the anti-tumor effect of CR in humans has been in part answered by the resistance of a cohort of women, who had suffered from anorexia in their early life, to breast cancer. However, human research on the beneficial effect of CR is still at an early stage and needs further validation. Though the complete mechanism of the anti-tumor effect of CR is far from clear, the plausible involvement of nutrient sensing pathways or IGF-1 pathways proposed for its anti-aging action cannot be overruled. In fact, cancer cell lines, mutant for proteins involved in IGF-1 pathways, failed to respond to CR. In addition, CR decreases the levels of many growth factors, anabolic hormones, inflammatory cytokines, and oxidative markers that are deregulated in several cancers. In this review, we discuss the anti-tumor effect of CR, describing experiments done in vitro in tumor models and in vivo in mouse models in which the tumor was induced by means of radiation or chemical exposure, expressing oncogenes or deleting tumor suppression genes. We also discuss the proposed mechanisms of CR anti-tumor action. Lastly, we argue the necessity of gene expression studies in cancerous versus normal cells upon CR.

War, forced displacement and growth in Laotian adults

BACKGROUND

Evidence from several populations suggests that war negatively impacts civilian nutrition, physical growth and overall health. This effect is often enduring or permanent, particularly if experienced early in life.

AIM

To assess whether the number of lifetime displacement experiences and being displaced in infancy were associated with adult height, sitting height, leg length and the sitting height ratio.

SUBJECTS AND METHODS

Retrospective questionnaires on displacement and resettlement experiences and anthropometric data were collected from a sample of Laotian adult refugees (ethnic Hmong and Lao; n = 365). All were born in Laos or Thailand and had resettled in French Guiana or the US. Many had been displaced several times by military conflict in Laos.

RESULTS

In bivariate analyses, being displaced in infancy and the number of lifetime displacement experiences one had were negatively associated with final adult height and leg length in both sexes. The association was stronger in females, particularly Hmong females. There was no significant association between total displacement experiences and the sitting height ratio. In multiple regression analyses, linear growth in males was negatively associated with being displaced in infancy; in females, the number of lifetime displacement experiences was a significant predictor.

CONCLUSION

Forced displacement from war appears to have a lasting effect on final adult height, sitting height and leg length, although not necessarily on the sitting height ratio in this sample.

Secular trend of menarche in Zagreb (Croatia) adolescents

OBJECTIVE

To study the secular trend of menarche in high-school urban adolescent girls (Zagreb, Croatia) over the last two decades, and to evaluate the possible impact of worsening of socio-economic conditions on age at menarche during the Croatian War of Independence (1991-1995).

STUDY DESIGN

Three surveys of female adolescents aged 15-19 years: (a) 523 girls interviewed in 1990, (b) 888 girls interviewed in 1997, and (c) 399 girls interviewed in 2010. Self-reported age at menarche (in decimal years) was presented by age groups and year of interview. Differences in mean age at menarche between adolescent age groups as well as between surveys were tested using One-way ANOVA.

RESULTS

The mean age at menarche was 12.82 years in 1990, 12.92 years in 1997 and 12.31 years in 2010. It increased by 0.10 years from 1990 to 1997 (p=0.290) and then declined by 0.61 years from 1997 to 2010 (p<0.001). Over the 20-year period, the overall mean age at menarche declined by 0.51 years (p<0.001).

CONCLUSION

The age at menarche in Zagreb adolescents continued to decline significantly from 1990 to 2010 (p<0.001), in spite of a statistically insignificant initial increase between 1990 and 1997. When put in broader context, age at menarche mirrored socio-economic changes in the war period.

Prenatal famine and adult health

We review human studies on the relation between acute exposures to prenatal famine and adult physical and mental health. These studies are observational and include exposures to a famine environment by natural or man-made causes or, more commonly, from the interplay between natural and human factors. These natural experiments provide an opportunity to examine long-term outcomes after famine exposures by comparing exposed and nonexposed individuals. The studies show consistent associations between prenatal famine and adult body size, diabetes, and schizophrenia. For other measures of adult health, findings are less robust. A relation between prenatal famine and some reported epigenetic changes may provide a potential mechanism to explain specific associations. Much progress can be made if current separate studies are further analyzed with comparable definitions of exposures and outcomes and using common analytic strategies.

Is low digit ratio linked with late menarche? Evidence from the BBC internet study

OBJECTIVES

Age at menarche (AAM) in the general population may be influenced by prenatal sex steroids. The ratio of the second and fourth digits (2D:4D) is a putative correlate of prenatal sex steroids, but the relationship of 2D:4D to AAM is controversial. Matchock ([2008]: Am J Hum Biol 20:487-489) has reported that right 2D:4D (but not left) was negatively related to AAM, but Helle ([2010a]: Am J Hum Biol 22:418-420) found no relationship. Here the association between 2D:4D, AAM, and self-reported rate of pubertal development (RPD) is considered.

METHODS

The sample consisted of self-measured finger lengths and AAM and RPD reported by women in the BBC internet study.

RESULTS

There were 70,658 white women who reported a mean (± SD) AAM of 12.54 (1.48) years. Right 2D:4D was negatively related to AAM and positively related to RPD. These relationships were independent of left 2D:4D, age and height. Between-country variation in right 2D:4D was also significantly related to AAM such that in countries with low 2D:4D women mean AAM was higher.

CONCLUSIONS

In support of the findings of Matchock, right 2D:4D was found to be negatively related to AAM. In addition, right 2D:4D was positively related to RPD. In a sample of 19 countries, mean right 2D:4D was negatively correlated with mean national AAM. These findings suggest that women with high prenatal testosterone and low prenatal estrogen tend to show late menarche and slow pubertal development.

Body composition trajectories into adolescence according to age at pubertal growth spurt

OBJECTIVE

To investigate whether the development of body composition into adolescence differs among children with an early, average, or late pubertal growth spurt (age at take-off [ATO]).

METHODS

Mixed-effect polynomial models were applied to serial anthropometric measurements spanning from 4 years before to 4 years after ATO in 215 DONALD participants. Sex-specific trajectories of fat mass index (FMI, FM/m(2) ), fat-free mass index (FFMI, FFM/m(2) ), and their z-scores were compared among those with an early, average, or late ATO.

RESULTS

Compared with girls with a late ATO (reference group), those with an early or average ATO experienced a significant increase in FFMI z-scores [β (standard error) for linear trends in early and average ATO group: +0.15 (0.05) FFMI z-scores/year (P = 0.001) and +0.11 (0.04) FFMI z-scores/year (P = 0.005), respectively, adjusted for early life factors]. Similar differences were observed in boys [adjusted β (standard error): +0.20 (0.06) FFMI z-scores/year (P = 0.0004) and +0.07 (0.05) FFMI z-scores/year (P = 0.1), respectively]. Graphical illustration of the predicted trajectories revealed that differences in relative FFMI emerged from ATO onward. For FMI, comparison with late maturers showed a more pronounced quadratic trend (kg/m(2) /years(2) ) (P = 0.01) among early-maturing girls and a reduced linear trend in FMI z-scores/year (P = 0.04) among early-maturing boys.

CONCLUSIONS

This longitudinal study suggests that children who experience an early pubertal growth spurt accrue progressively more fat-free mass during the first years of puberty than late-maturing peers of the same age. Higher levels of adiposity commonly observed in adults with early puberty onset are, thus, likely to develop subsequently in later adolescence.

The timing of puberty: is it changing? Does it matter?

Whether the secular trend of a decreasing age of puberty has continued over the past 50 years remains controversial. Data that had been classically used to address this issue are reviewed and large epidemiologic studies, which had not previously been included, are now considered to challenge the conclusions of prior debates of this topic. The effect and timing of excessive weight gain are discussed in detail and recent observations about the opposing effects of obesity on the pubertal timing of girls versus boys are considered. The second half of the review examines both the causes and the long-term health consequences of early puberty, touching on the possible effect of stress and endocrine-disrupting chemicals along with the risks of reproductive cancers, metabolic syndrome, and psychosocial consequences during adolescence and beyond.

Childhood and adolescent energy restriction and subsequent colorectal cancer risk: results from the Netherlands Cohort Study

BACKGROUND

Energy restriction during childhood and adolescence is suggested to lower colorectal cancer (CRC) risk. We investigated this in the Netherlands Cohort Study.

METHODS

Information on diet and other risk factors was collected by a baseline questionnaire in 1986 when cohort members were 55-69 years of age (n = 120 852). Three indicators of early life exposure to energy restriction were assessed: father's employment status during the Economic Depression (1932-40), place of residence during Second World War years (1940-44) and the 'Hunger Winter' (1944-45), a severe famine. Using the case-cohort approach, incidence rate ratios (RRs) and 95% confidence intervals (CIs) were calculated for total colorectal, proximal colon, distal colon, rectosigmoid and rectal cancers, according to the three time periods of energy restriction. After 16.3 years of follow-up, 2573 cases were available for multivariate analyses.

RESULTS

Men who lived in a western city during the Hunger Winter and therefore exposed to the highest degree of energy restriction, had a lower risk of developing CRC (RR: 0.81, 95% CI: 0.68-0.98), and tumours of the proximal colon (RR: 0.72, 95% CI: 0.54-0.96) and rectum (RR: 0.71, 95% CI: 0.53-0.96). In women, non-statistically significant inverse associations were observed for tumours of the distal colon, rectosigmoid and rectum. Inverse associations were also observed between the other two exposure times and studied endpoints, though not statistically significant.

CONCLUSIONS

This unique observational evidence suggests that severe energy restriction during childhood and adolescence may lower CRC risk, especially in men, thus providing insight regarding the role of energy intake during early life in CRC development.

Early life exposure to famine and colorectal cancer risk: a role for epigenetic mechanisms

BACKGROUND

Exposure to energy restriction during childhood and adolescence is associated with a lower risk of developing colorectal cancer (CRC). Epigenetic dysregulation during this critical period of growth and development may be a mechanism to explain such observations. Within the Netherlands Cohort Study on diet and cancer, we investigated the association between early life energy restriction and risk of subsequent CRC characterized by the (promoter) CpG island methylation phenotype (CIMP).

METHODOLOGY/PRINCIPAL FINDINGS

Information on diet and risk factors was collected by baseline questionnaire (n = 120,856). Three indicators of exposure were assessed: place of residence during the Hunger Winter (1944-45) and World War II years (1940-44), and father's employment status during the Economic Depression (1932-40). Methylation specific PCR (MSP) on DNA from paraffin embedded tumor tissue was performed to determine CIMP status according to the Weisenberger markers. After 7.3 years of follow-up, 603 cases and 4631 sub-cohort members were available for analysis. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals for CIMP+ (27.7%) and CIMP- (72.3%) tumors according to the three time periods of energy restriction, adjusted for age and gender. Individuals exposed to severe famine during the Hunger Winter had a decreased risk of developing a tumor characterized by CIMP compared to those not exposed (HR 0.65, 95%CI: 0.45-0.92). Further categorizing individuals by an index of '0-1' '2-3' or '4-7' genes methylated in the promoter region suggested that exposure to the Hunger Winter was associated with the degree of promoter hypermethylation ('0-1 genes methylated' HR = 1.01, 95%CI:0.74-1.37; '2-3 genes methylated' HR = 0.83, 95% CI:0.61-1.15; '4-7 genes methylated' HR = 0.72, 95% CI:0.49-1.04). No associations were observed with respect to the Economic Depression and WWII years.

CONCLUSIONS

This is the first study indicating that exposure to a severe, transient environmental condition during adolescence and young adulthood may result in persistent epigenetic changes that later influence CRC development.

Early life circumstances and their impact on menarche and menopause

Ages at menarche and menopause have been shown to be associated with adverse health outcomes in later life. For example, earlier menarche and later menopause have been independently linked to higher risk of breast cancer. Earlier menarche may also be associated with an increased risk of endometrial cancer, menstrual problems and adult obesity. Given the associations of ages at menarche and menopause with future health outcomes, it is important to establish what factors across life, and generations, may influence these. This article examines the associations of early life factors, namely birthweight, bodyweight and growth during childhood, childhood socioeconomic circumstances and psychosocial factors with ages at menarche and menopause. It examines possible explanations of the associations found, including life history theory, and discusses areas for future research.

Age at menarche in a Chuvashian rural population

OBJECTIVES

The secular trend and familial influences on age at menarche among a rural Chuvashian population was examined in a cross-sectional community-based study.

SUBJECTS AND METHODS

The cohort included 617 females aged 18-80 years, with age at menarche ranging from 10 to 24 years (mean 15.4 +/- 2.1). Statistical analyses included simple linear regression, maximum likelihood estimation and a whiskers plot.

RESULTS

Women born during the second through the fourth decade of the 20th century showed increasing mean values of age at menarche from 15.4 (second decade) up to 16.5 (fourth decade). Women born after the fourth decade showed a decrease in mean values from 15.5 (fifth decade) to 13.0 (ninth decade). The highest peak of age at menarche was in women born in 1932. Significant familial correlations were observed between adjusted to year of birth age at menarche in mothers and daughters r = 0.195, p<0.01 and sisters and sisters r = 0.404, p<0.01.

CONCLUSION

Our study demonstrated the certain secular trends of age at menarche in Chuvashian women who matured after World War II. Periods of socio-economic disasters such as war and famine disrupt the secular trend. Our findings also confirm the hypothesis of significant familial influences on menarcheal age.

Growing up under generalized violence: an ecological study of homicide rates and secular trends in age at menarche in Colombia, 1940s-1980s

We examined secular changes in mean age at menarche among 5577 Colombian women born between 1941 and 1989, and correlated those changes with nation-wide rates of homicide and real gross domestic product per capita (GDP) at the year of birth and at the year at age 5, within predefined historical periods. The mean (standard error) rate of change in age at menarche by year of birth was -0.55 (0.02) years/decade. The rate of change was not constant, but varied between historical periods as follows: -1.44, -0.14, -0.60, and -0.36 years/decade for the periods 1941-1947, 1948-1958, 1959-1978, and 1979-1989, respectively. The changes in age at menarche correlated positively with the changes in the nation-wide rates of homicide within such periods; i.e. decelerations in the menarcheal trend coincided with increases in the rates of homicide and vice versa. The correlation was higher with the rates of homicide when women were 5 years of age (r=0.99, p=0.01) compared to the rates of homicide at the year of birth (0.55, p=0.45). There were negative correlations between the changes in age at menarche and the changes in GDP, but they were weaker than those with the rates of homicide. These results could suggest a potential impact on maturation of psychosocial stress in childhood due to exposure to a generalized atmosphere of violence and fear.

Forty years trends in timing of pubertal growth spurt in 157,000 Danish school children

BACKGROUND

Entering puberty is an important milestone in reproductive life and secular changes in the timing of puberty may be an important indicator of the general reproductive health in a population. Too early puberty is associated with several psychosocial and health problems. The aim of our study was to determine if the age at onset of pubertal growth spurt (OGS) and at peak height velocity (PHV) during puberty show secular trends during four decades in a large cohort of school children.

METHODS AND FINDINGS

Annual measurements of height were available in all children born from 1930 to 1969 who attended primary school in the Copenhagen Municipality. 135,223 girls and 21,612 boys fulfilled the criteria for determining age at OGS and age at PHV. These physiological events were used as markers of pubertal development in our computerized method in order to evaluate any secular trends in pubertal maturation during the study period (year of birth 1930 to 1969). In this period, age at OGS declined statistically significantly by 0.2 and 0.4 years in girls and boys, respectively, whereas age at PHV declined statistically significantly by 0.5 and 0.3 years in girls and boys, respectively. The decline was non-linear with a levelling off in the children born between 1940 and 1955. The duration of puberty, as defined by the difference between age at OGS and age at PHV, increased slightly in boys, whereas it decreased in girls.

CONCLUSION

Our finding of declining age at OGS and at PHV indicates a secular trend towards earlier sexual maturation of Danish children born between 1930 and 1969. Only minor changes were observed in duration of puberty assessed by the difference in ages at OGS and PHV.

Reproductive traits following a parent-child separation trauma during childhood: a natural experiment during World War II

Given the ethical limitations of exposing children to experimentally manipulated adverse experiences, evidence of the effects of childhood traumas on subsequent life history are based mostly on women's retrospective reports and animal studies. Only a few prospective studies have assessed the life-long consequences of childhood trauma. We asked whether a traumatic separation from both parents during childhood is associated with reproductive and marital traits later in life, measured by age of onset of menarche, timing of menopause, period of fertile years, age at first childbirth, birth spacing, number of children, and history of divorce. We studied members of the 1934-1944 Helsinki Birth Cohort, including 396 former war evacuees from varying socioeconomic backgrounds, who were sent unaccompanied by their parents to temporary foster families in Sweden and Denmark, and 503 participants who had no separation experiences. Data on separation experiences, number of children, and divorces experienced came from national registers, and the remaining data from a survey among the participants aged 61.6 years (SD = 2.9). Former evacuees had earlier menarche, earlier first childbirth (men), more children by late adulthood (women), and shorter interbirth intervals (men), than the non-separated. A traumatic experience in childhood is associated with significant alterations in reproductive and marital traits, which characterize both women and men. The implications are relevant to the 9.2 million child refugees living throughout the world today.

A comparative analysis of estimation of age at menarche by various methods in women participating in the Krakow Longitudinal Growth Study, Poland

The purpose of this study was to see whether menarcheal age assessment by means of the most frequently used methods that were conducted every time on the same group of girls would yield the same results. One hundred and one Polish girls, whose ages at menarche were recorded in a longitudinal study between 1976 and 1990, were asked to recall the age of menarche in 2004. The mean menarcheal ages of those women were calculated by means of the probit (PA), prospective (AA), retrospective method without age correction (RA), and retrospective method with the recall age corrected by 0.5 year (RcA). The PA, AA, and retrospective methods: RA and RcA revealed results: 13.14 +/- 1.1; 13.10 +/- 1.1; 13.12 +/- 1.36, and 14.39 +/- 1.34 years, respectively. The menarcheal AA was insignificantly different from the PA (95% CI) and RA. The RcA was significantly higher than the AA and RA (P = 0.05). The correlation coefficient (r) between AA and RA was 0.70. Only 16% of the interviewed women accurately remembered the date of their menarche, 63% of them missed their menarche time by about 1 year, whereas 22% were wrong by 2 and more years. (1) The PA and the AA method yield comparable results when estimating menarcheal age. (2) The menarcheal age determined by the retrospective methods is not very reliable and the application of age correction overestimates the results.

Menstruation during and after caloric restriction: the 1944-1945 Dutch famine

OBJECTIVE

To investigate the relation between exposure to the 1944-45 Dutch famine and concurrent and subsequent menstrual disturbances.

DESIGN

Cohort study.

SETTING

Doorlopend Onderzoek Mammacarcinoom breast cancer screening project, Utrecht, the Netherlands.

PATIENT(S)

Between 1983 and 1986, approximately 12,500 women (born 1911-41) reported their individual famine experiences.

MAIN OUTCOME MEASURE(S)

Irregular menstruation during the famine; time to regular menses after menarche, and menstrual patterns in adulthood after childhood famine.

RESULT(S)

The famine had a direct impact on menstruation. The odds ratio (OR) of concurrent irregular menses in severely versus unexposed women was 8.85 (95% confidence interval [CI], 7.31-10.70). Women exposed to severe famine before menarche were 1.51 (95% CI, 1.15-1.98) times more likely to experience irregular menses for a prolonged time after menarche compared with the unexposed. This association was stronger in women with an early menarche. When the menstrual pattern was assessed in adulthood by menstrual diaries, a nonsignificant tendency of increased irregularity (OR, 1.13; 95% CI, 0.82-1.54) and regular but long menstrual cycles (OR, 1.41; 95% CI, 0.89-2.23) was observed in women exposed to severe famine.

CONCLUSION(S)

Famine relates to concurrent menstrual irregularity, and exposure in childhood seems to affect the subsequent menstrual pattern.

The impact of the Occupation of Guernsey 1940-1945 on breast cancer risk factors and incidence

To examine the impact of the German Occupation of Guernsey (1940-1945) on breast cancer risk factors and incidence. Under study were 1019 women who stayed, or whose mothers had stayed, in Guernsey, and 1358 women evacuated or born to evacuated mothers. Amongst those born 1926-1934 who remained in Guernsey, the secular trend of earlier menarche disappeared: menarche was delayed by 12 months for those born in 1930. By March 2006, 97 breast cancers had been diagnosed, 37 in the occupied group. Unusually, higher age at menarche appeared to be associated with increased risk of breast cancer (>or=14 years vs. <or=13 years: HR = 1.52, 95% CI = 0.80-2.92). Separate analyses by birth cohort revealed a non-significantly higher incidence in the subgroup born from 1926 to 1934 (HR = 1.30, 95% CI = 0.62-2.76). Delay in menarche among women remaining in Guernsey during the Occupation, rather than being protective, was associated with an increased risk of breast cancer.

Blood pressure, hypertension and mortality from circulatory disease in men and women who survived the siege of Leningrad

The population of Leningrad suffered from severe starvation, cold and psychological stress during the siege in 1941-1944. We investigated long-term effects of the siege on cardiovascular risk factors and mortality in surviving men and women. 3905 men born 1916-1935 and 1729 women born 1910-1940, resident in St Petersburg (formerly Leningrad) between 1975 and 1982, of whom a third experienced the siege as children, adolescents or young adults, were examined for cardiovascular risk factors in 1975-1977 and 1980-1982 respectively and followed till end 2005. Effects of siege exposure on blood pressure, lipids, body size, and mortality were studied in multivariate analysis stratified by gender and period of birth, adjusted for age, smoking, alcohol and social characteristics. Women who were 6-8 years-old and men who were 9-15 years-old at the peak of starvation had higher systolic blood pressure compared to unexposed subjects born during the same period of birth (fully adjusted difference 8.8, 95% CI: 0.1-17.5 mm Hg in women and 2.9, 95% CI: 0.7-5.0 mm Hg in men). Mean height of women who were exposed to siege as children appeared to be greater than that of unexposed women. Higher mortality from ischaemic heart disease and cerebrovascular disease was noted in men exposed at age 6-8 and 9-15, respectively. The experience of severe stress and starvation in childhood and puberty may have long-term effects on systolic blood pressure and circulatory disease in surviving men and women with potential gender differences in the effect of siege experienced at pre-pubertal age.

Changes in reproductive indices in Chuvashian women whose maturation was during World War II

OBJECTIVES

The aim of the present study was to evaluate whether Chuvashian women whose maturation was during World War II and the subsequent rehabilitation period were different from women born at other times in terms of age at menarche and age at menopause.

DESIGN

The cohort included 745 Chuvashian females aged 18-90 years; age at menarche (N=653), ranged from 10 to 24 years (mean 15.42+/-2.11). Data regarding menopausal age was obtained from 322 females born between 1915 and 1950 (mean 48.5+/-4.6). We computed descriptive statistics of the age of menopause and the age of menarche for different birth cohorts; we compared the mean values by Student's t-test and the variances by F-test.

RESULTS

The "expected" maturation period of women whose age at menarche >20 and most women whose age at menopause < or =38 was between 1939 and 1950. Women whose age at menarche >20 showed normal parameters regarding age at menopause, and women whose age at menopause was < or =38 showed normal parameters of age at menarche. The variances of age at menopause in women born from 1925 to 1936 was almost two-fold higher than in women born earlier and afterwards (p=0.0003). The difference in the mean ages was significant for both menarche (p=0.005) and menopause (p=0.001).

CONCLUSION

Periods of socioeconomic disasters such as war and famine can influence women's age at menarche and age at menopause. Women, whose maturation occurred during or immediately after World War II, showed a higher mean age at menarche and a wider dispersion of age at menopause than other women.

Hormonal aspects in the causation of human breast cancer: epidemiological hypotheses reviewed, with special reference to nutritional status and first pregnancy

Epidemiology of breast cancer has identified early age at menarche, late first pregnancy, low parity and late menopause as risk factors, but in addition genetic factors, height, weight and living in western countries play a significant role. The international variation in incidence is almost exclusively due to non-genetic factors. Hypotheses in prevention-oriented research are reviewed: 1. obesity-related oestrogen production as a stimulus of the tumour in postmenopausal women; 2. nutritional status and energy expenditure during puberty and adolescence, developed for fertility and fecundity and extended later to breast cancer; 3. reproductive life during early adulthood, age at first pregnancy and its specific effects on breast tissues. The message of preventability of breast cancer is that mammary epithelial differentiation should come early. Our insight concerning events in puberty and early adulthood can be consolidated in one concept on the risk of extended proliferation of breast epithelium during early adulthood in the absence of full differentiation induced by pregnancy. The combined effects of Western-type nutrition, lack of exercise and Western-type women's emancipation sets the stage for breast cancer already at a young age. Since it is unlikely that emancipated women in affluent societies will return to the original life-style of getting pregnant as soon as it is biologically possible, a novel daring way of protection has to be considered. Could a "Breast Differentiation Pill" be developed to offer protection?

Age at menarche in relation to adult height: the EPIC study

In the last two centuries, age at menarche has decreased in several European populations, whereas adult height has increased. It is unclear whether these trends have ceased in recent years or how age at menarche and height are related in individuals. In this study, the authors first investigated trends in age at menarche and adult height among 286,205 women from nine European countries by computing the mean age at menarche and height in 5-year birth cohorts, adjusted for differences in socioeconomic status. Second, the relation between age at menarche and height was estimated by linear regression models, adjusted for age at enrollment between 1992 and 1998 and socioeconomic status. Mean age at menarche decreased by 44 days per 5-year birth cohort (beta = -0.12, standard error = 0.002), varying from 18 days in the United Kingdom to 58 days in Spain and Germany. Women grew 0.29 cm taller per 5-year birth cohort (standard error = 0.007), varying from 0.42 cm in Italy to 0.98 cm in Denmark. Furthermore, women grew approximately 0.31 cm taller when menarche occurred 1 year later (range by country: 0.13-0.50 cm). Based on time trends, more recent birth cohorts have their menarche earlier and grow taller. However, women with earlier menarche reach a shorter adult height compared with women who have menarche at a later age.

Timing of pubertal maturation in girls: an integrated life history approach

Life history theory provides a metatheoretical framework for the study of pubertal timing from an evolutionary-developmental perspective. The current article reviews 5 middle-level theories--energetics theory, stress-suppression theory, psychosocial acceleration theory, paternal investment theory, and child development theory--each of which applies the basic assumptions of life history theory to the question of environmental influences on timing of puberty in girls. These theories converge in their conceptualization of pubertal timing as responsive to ecological conditions but diverge in their conceptualization of (a) the nature, extent, and direction of environmental influences and (b) the effects of pubertal timing on other reproductive variables. Competing hypotheses derived from the 5 perspectives are evaluated. An extension of W. T. Boyce and B. J. Ellis's (in press) theory of stress reactivity is proposed to account for both inhibiting and accelerating effects of psychosocial stress on timing of pubertal development. This review highlights the multiplicity of (often unrecognized) perspectives guiding research, raises challenges to virtually all of these, and presents an alternative framework in an effort to move research forward in this arena of multidisciplinary inquiry.

Breast cancer and the brain: a neurodevelopmental hypothesis to explain the opposing effects of caloric deprivation during the Dutch famine of 1944-1945 on breast cancer and its risk factors

Most studies on calorie deprivation and cancer risk in rodents show reductions in tumor occurrence. However, the few human studies on calorie restriction are conflicting. An overview is given of results in the DOM (diagnostic onderzoek mammacarcinoom) cohorts among women exposed to the Dutch Famine of 1944-1945. Opposing effects were found on risk factors (shortening of leg length, later menarche, and earlier menopause), whereas urinary estrogens and plasma insulin-like growth factor (IGF)-1 and IGF binding protein-3 were increased, as was breast cancer itself. Exposure between 2 and 10 y old was an unexpected window of susceptibility to the effects of calorie deprivation. The effects of famine exposure were most clearly seen in women who never gave birth. These opposing observations can be explained by a neurodevelopmental hypothesis on set-point shifts at the level of the diencephalons/hypothalamus, either directly or from rebound effects. Such a mechanism reflects old evolutionary adaptation systems in lower and higher organisms to cope with periods of stress and famine by adjusting, for example, reproductive functions. These effects in exposed women may later also affect their unexposed offspring. This hypothesis provides several testable, hormone-mediated corollaries on the relationships between the role of calories in a Westernized lifestyle and human cancer risk. The underlying developmental perspective, as opposed to a risk factor approach, can explain why certain ages, even before breast development, are especially sensitive to effects of large fluctuations in calories. The observations presented may have implications for preventive strategies such as promoting moderation of calorie intake to curb cancer risks.

Calorie restriction, aging, and cancer prevention: mechanisms of action and applicability to humans

Calorie restriction (CR) is the most effective and reproducible intervention for increasing lifespan in a variety of animal species, including mammals. CR is also the most potent, broadly acting cancer-prevention regimen in experimental carcinogenesis models. Translation of the knowledge gained from CR research to human chronic disease prevention and the promotion of healthy aging is critical, especially because obesity, which is an important risk factor for several chronic diseases, including many cancers, is alarmingly increasing in the Western world. This review synthesizes the key biological mechanisms underlying many of the beneficial effects of CR, with a particular focus on the insulin-like growth factor-1 pathway. We also describe some of the opportunities now available for investigations, including gene expression profiling studies, the development of pharmacological mimetics of CR, and the integration of CR regimens with targeted, mechanism-based interventions. These approaches will facilitate the translation of CR research into strategies for effective human chronic disease prevention.

Energy restriction early in life and colon carcinoma risk: results of The Netherlands Cohort Study after 7.3 years of follow-up

BACKGROUND

This study evaluated the effects of severe undernutrition during adolescence and subsequent colon carcinoma risk.

METHODS

The authors evaluated The Netherlands Cohort Study on Diet and Cancer (NLCS) among 62,573 women and 58,279 men aged 55-69 years at baseline. Information on diet and risk factors was collected by questionnaire in 1986. Additional information was collected concerning residence during the hunger winter (1944-1945), the World War II years (1940-1944), and father's employment status during the economic depression of 1932-1940, which were used as indicators of exposure. After 7.3 years of follow-up, 807 colon carcinoma cases (388 females and 419 males) were available for analysis.

RESULTS

Multivariate analysis showed that both men and women who had lived in a western city in 1944-1945 had a decreased colon carcinoma risk (men: relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.62-1.16; women: RR = 0.80, 95% CI = 0.59-1.09). No association between colon carcinoma risk and urban versus rural residence was found during the war years (1940-1944). Having an unemployed father during the economic depression (1932-1940) was also associated with a small decrease in colon carcinoma risk for men (RR = 0.90, 95% CI =0.62-1.31) and women (RR = 0.75, 95% CI 0.49-1.14). In subgroup analyses, a decreased colon carcinoma risk for men and women who were in their adolescent growth spurt and living in a western city during the hunger winter of 1944-1945 was noted (men: RR = 0.72, 95% CI = 0.31-1.65; women: RR = 0.88, 95% CI = 0.40-1.96). No associations were statistically significant because of the limited study size.

CONCLUSIONS

In the current study, a weak inverse relation was found between energy restriction early in life and subsequent colon carcinoma risk for men and women. However, these findings need replication in a larger study.

Breast cancer incidence rates in Slovenia 1971-1993

BACKGROUND

Analyses of time trends in breast cancer incidence and mortality have generally revealed cohort-based changes in the rates. These have been linked to cohort-based changes in lifestyle factors. The effect of the changes in the reproductive risk factors on the changes in the rates, and the relative importance of the reproductive characteristics in Slovenia, a country which has not had much breast cancer screening, are investigated.

METHODS

Data on breast cancer incidence for 1971-1993 were obtained from the Cancer Registry of Slovenia (Registry). The Registry covers the whole population of the Republic of Slovenia (1.99 million on 30 June 1993). The statistical analysis uses parametric age-period-cohort models.

RESULTS

Breast cancer incidence has increased by 70% in Slovenia from 1971 to 1993, These changes are dominated by cohort effects and the cohorts born in 1907-1922 have the greatest increase in incidence. Period effects on changes in incidence were modest. The percentage of nulliparous women in the cohort and the average family size in the cohort explained 38% of the variation in the cohort effects.

CONCLUSIONS

The percentage of nulliparous women in the cohort is the most important reproductive variable associated with the trends in the rates, with breast cancer risk predicted to be higher in cohorts with a larger percentage of nulliparous women. As the cohorts born 1932-1946 have a more favourable reproductive pattern as regards breast cancer risk, compared to the 1907-1922 cohorts, age-specific incidence rates in Slovenia would be predicted to decline in the future in the absence of changes in the other risk factors.

Changes in menarcheal age in girls exposed to war conditions

The purpose of this study was to assess changes in mean menarcheal age of girls in the city of Sibenik in the period from mid-1980s to the mid-1990s. Sibenik is a Dalmatian town which was exposed to hard war conditions in 1991-1995. Menarcheal status of Sibenik girls was surveyed three times, in 1981, 1985, and 1996, and included 720, 1,207, and 1,680 girls, respectively, ages 9.5-16.5 years. Mean menarcheal age was estimated by the status quo method and application of probit analysis. Results show a slight decrease in menarcheal age from 1981 to 1985 (from 12.97 +/- 0.06 years to 12.87 +/- 0.05), and then a significant increase from 12.87 +/- 0.05 years in 1985 to 13.13 +/- 0.10 years in 1996. The increase in mean menarcheal age occurred in all socioeconomic groups based on parental occupation and number of siblings. In the group of girls whose homes were damaged during war, menarche occurred at an average of 13.53 +/- 0.14 years, while those who lost a family member experienced menarche at an older mean age, 13.76 +/- 0.27 years. However, when the girls who experienced personal tragedies were excluded the onset of menarche was still later than in girls surveyed in the earlier periods. The results suggest that the general reversal in the secular trend of menarcheal age in Sibenik girls can be attributed to persistent psychological pressures and uncertainties associated with conditions of war. Am. J. Hum. Biol. 12:503-508, 2000. Copyright 2000 Wiley-Liss, Inc.

A woman's build and the risk of breast cancer

A woman's build and the risk of breast cancer seem to be related. While relative overweight, as described by the body mass index, seems to be associated with increased breast cancer risk in postmenopausal women, overweight in premenopausal women seems slightly protective. Papers from a MEDLINE search are reviewed regarding the association between build and the development of breast cancer. Different aspects of build, such as height, weight, body mass index and body shape, are discussed. The more prominent associations found through this search are a positive association between height and breast cancer risk both in pre- and postmenopausal women. Regarding body mass index, the association is negative in premenopausal women and positive in postmenopausal women. Body shape described as masculine versus feminine seems to have no impact on breast cancer risk in premenopausal women, but seems to be positively associated with breast cancer in postmenopausal women. Possible biological mechanisms responsible for the associations with breast cancer risk are discussed, including endogenous oestrogens, androgens and glucose metabolic substances. Avoiding or reducing postmenopausal overweight may modify breast cancer risk indicators in a more favourable direction.