Carol M. Worthman

Puberty and depression: the roles of age, pubertal status and pubertal timing

BACKGROUND Previous work has indicated that the 2:1 female:male sex ratio in unipolar depressive disorders does not emerge until some time between ages 10 and 15. METHODS Data from four annual waves of data collection from the Great Smoky Mountains Study (GSMS) involving children aged nine to 16 were employed. RESULTS Pubertal status better predicted the emergence of the expected sex ratio than did age. Only after the transition to mid-puberty (Tanner Stage III and above) were girls more likely than boys to be depressed. The timing of this transition had no effect on depression rates. Before Tanner Stage III, boys had higher rates of depression than girls, and the prevalence of depression appeared to fall in boys at an earlier pubertal stage than that at which it began to rise in girls. In addition, recent transition to Tanner Stage III or higher had a transient effect in reducing the prevalence of depression in boys. CONCLUSIONS The period of emergence of increased risk for depression in adolescent girls appears to be a relatively sharply demarcated developmental transition occurring in mid-puberty. Previously reported effects of the timing of puberty (which have tended to be transient) appeared less important in increase of risk for depression than pubertal status.

Pubertal changes in hormone levels and depression in girls

BACKGROUND Throughout their reproductive years, women suffer from a higher prevalence of depression than men. Before puberty, however, this is not the case. In an earlier study, we found that reaching Tanner Stage III of puberty was associated with increased levels of depression in girls. This paper examines whether the morphological changes associated with puberty (as measured by Tanner stage) or the hormonal changes underlying them are more strongly associated with increased rates of depression in adolescent girls. METHODS Data from three annual waves of interviews with 9 to 15-year-olds from the Great Smoky Mountains study were analysed. RESULTS Models including the effects of testosterone and oestradiol eliminated the apparent effect of Tanner stage. The effect of testosterone was non-linear. FSH and LH had no effects on the probability of being depressed. CONCLUSIONS These findings argue against theories that explain the emergence of the female excess of depression in adulthood in terms of changes in body morphology and their resultant psychosocial effects on social interactions and self-perception. They suggest that causal explanations of the increase in depression in females need to focus on factors associated with changes in androgen and oestrogen levels rather than the morphological changes of puberty.

Intergroup aggression in chimpanzees and humans.

The occurrence of fatal attacks during intergroup encounters among chimpanzees suggests that certain aspects of chimpanzee and human intergroup aggression may be explicable in similar ways. This paper addresses three questions: What conditions favor the evolution of lethal raiding in intergroup aggression? Why is intergroup aggression in these two species predominantly the domain of males? Under what circumstances do groups compete over access to females as opposed to material resources? Examination of comparative data on nonhuman primates and crosscultural study of foraging societies suggests that attacks are lethal because where there is sufficient imbalance of power their cost is trivial, that these attacks are a male and not a female activity because males are the philopatric sex, and that it is resources of reproductive interest to males that determine the causes of intergroup aggression.

Testosterone, antisocial behavior, and social dominance in boys: pubertal development and biosocial interaction

BACKGROUND Studies linking testosterone and antisocial behavior in humans have produced mixed results. Adolescence offers a promising period to study this relationship; circulating testosterone increases dramatically in boys during puberty, and antisocial behavior increases during the same period. METHODS Our analyses were based on boys aged 9-15 years who were interviewed during the first three waves of the Great Smoky Mountains Study. Measures included interview assessment of DSM-IV conduct disorder (CD) symptoms and diagnosis, blood spot measurement of testosterone, Tanner staging of pubertal development, and assessment of leadership behaviors and peer deviance. RESULTS The adolescent rise in CD was primarily attributable to an increase in nonphysically aggressive behaviors. Increasing levels of circulating testosterone and association with deviant peers contributed to these age trends. There was no evidence that physical aggression was related to high testosterone. Evidence of biosocial interactions was identified; testosterone was related to nonaggressive CD symptoms in boys with deviant peers and to leadership in boys with nondeviant peers. CONCLUSIONS The results are consistent with the hypothesis that testosterone relates to social dominance, with the assumption that behaviors associated with dominance differ according to social context.

Puberty Influences Medial Temporal Lobe and Cortical Gray Matter Maturation Differently in Boys Than Girls Matched for Sexual Maturity

Sex differences in age- and puberty-related maturation of human brain structure have been observed in typically developing age-matched boys and girls. Because girls mature 1-2 years earlier than boys, the present study aimed at assessing sex differences in brain structure by studying 80 adolescent boys and girls matched on sexual maturity, rather than age. We evaluated pubertal influences on medial temporal lobe (MTL), thalamic, caudate, and cortical gray matter volumes utilizing structural magnetic resonance imaging and 2 measures of pubertal status: physical sexual maturity and circulating testosterone. As predicted, significant interactions between sex and the effect of puberty were observed in regions with high sex steroid hormone receptor densities; sex differences in the right hippocampus, bilateral amygdala, and cortical gray matter were greater in more sexually mature adolescents. Within sex, we found larger volumes in MTL structures in more sexually mature boys, whereas smaller volumes were observed in more sexually mature girls. Our results demonstrate puberty-related maturation of the hippocampus, amygdala, and cortical gray matter that is not confounded by age, and is different for girls and boys, which may contribute to differences in social and cognitive development during adolescence, and lasting sexual dimorphisms in the adult brain.

Women's Reproductive Cancers in Evolutionary Context

Reproductive experiences for women in todays affluent Western nations differ from those of women in hunting and gathering societies, who continue the ancestral human pattern. These differences parallel commonly accepted reproductive risk factors for cancers of the breast, endometrium and ovary. Nutritional practices, exercise requirements, and body composition are nonreproductive influences that have been proposed as additional factors affecting the incidence of womens cancers. In each case, these would further increase risk for women in industrialized countries relative to forager women. Lifestyles and reproductive patterns new from an evolutionary perspective may promote womens cancer. Calculations based on a theoretical model suggest that, to age 60, modern Western women have a breast cancer risk as much as 100 times that of preagricultural women.

Comparison of mental health between former child soldiers and children never conscripted by armed groups in Nepal.

CONTEXT Former child soldiers are considered in need of special mental health interventions. However, there is a lack of studies investigating the mental health of child soldiers compared with civilian children in armed conflicts. OBJECTIVE To compare the mental health status of former child soldiers with that of children who have never been conscripts of armed groups. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional cohort study conducted in March and April 2007 in Nepal comparing the mental health of 141 former child soldiers and 141 never-conscripted children matched on age, sex, education, and ethnicity. MAIN OUTCOME MEASURES Depression symptoms were assessed via the Depression Self Rating Scale, anxiety symptoms via the Screen for Child Anxiety Related Emotional Disorders, symptoms of posttraumatic stress disorder (PTSD) via the Child PTSD Symptom Scale, general psychological difficulties via the Strength and Difficulties Questionnaire, daily functioning via the Function Impairment tool, and exposure to traumatic events via the PTSD Traumatic Event Checklist of the Kiddie Schedule of Affective Disorders and Schizophrenia. RESULTS Participants were a mean of 15.75 years old at the time of this study, and former child soldiers ranged in age from 5 to 16 years at the time of conscription. All participants experienced at least 1 type of trauma. The numbers of former child soldiers meeting symptom cutoff scores were 75 (53.2%) for depression, 65 (46.1%) for anxiety, 78 (55.3%) for PTSD, 55 (39.0%) for psychological difficulties, and 88 (62.4%) for function impairment. After adjusting for traumatic exposures and other covariates, former soldier status was significantly associated with depression (odds ratio [OR], 2.41; 95% confidence interval [CI], 1.31-4.44) and PTSD among girls (OR, 6.80; 95% CI, 2.16-21.58), and PTSD among boys (OR, 3.81; 95% CI, 1.06-13.73) but was not associated with general psychological difficulties (OR, 2.08; 95% CI, 0.86-5.02), anxiety (OR, 1.63; 95% CI, 0.77-3.45), or function impairment (OR, 1.34; 95% CI, 0.84-2.14). CONCLUSION In Nepal, former child soldiers display greater severity of mental health problems compared with children never conscripted by armed groups, and this difference remains for depression and PTSD (the latter especially among girls) even after controlling for trauma exposure.

Ventilation and hypoxic ventilatory response of Tibetan and Aymara high altitude natives

Newcomers acclimatizing to high altitude and adult male Tibetan high altitude natives have increased ventilation relative to sea level natives at sea level. However, Andean and Rocky Mountain high altitude natives have an intermediate level of ventilation lower than that of newcomers and Tibetan high altitude natives although generally higher than that of sea level natives at sea level. Because the reason for the relative hypoventilation of some high altitude native populations was unknown, a study was designed to describe ventilation from adolescence through old age in samples of Tibetan and Andean high altitude natives and to estimate the relative genetic and environmental influences. This paper compares resting ventilation and hypoxic ventilatory response (HVR) of 320 Tibetans 9-82 years of age and 542 Bolivian Aymara 13-94 years of age, native residents at 3,800-4,065 m. Tibetan resting ventilation was roughly 1.5 times higher and Tibetan HVR was roughly double that of Aymara. Greater duration of hypoxia (older age) was not an important source of variation in resting ventilation or HVR in either sample. That is, contrary to previous studies, neither sample acquired hypoventilation in the age ranges under study. Within populations, greater severity of hypoxia (lower percent of oxygen saturation of arterial hemoglobin) was associated with slightly higher resting ventilation among Tibetans and lower resting ventilation and HVR among Aymara women, although the associations accounted for just 2-7% of the variation. Between populations, the Tibetan sample was more hypoxic and had higher resting ventilation and HVR. Other systematic environmental contrasts did not appear to elevate Tibetan or depress Aymara ventilation. There was more intrapopulation genetic variation in these traits in the Tibetan than the Aymara sample. Thirty-five percent of the Tibetan, but none of the Aymara, resting ventilation variance was due to genetic differences among individuals. Thirty-one percent of the Tibetan HVR, but just 21% of the Aymara, HVR variance was due to genetic differences among individuals. Thus there is greater potential for evolutionary change in these traits in the Tibetans. Presently, there are two different ventilation phenotypes among high altitude natives as compared with sea level populations at sea level: lifelong sustained high resting ventilation and a moderate HVR among Tibetans in contrast with a slightly elevated resting ventilation and a low HVR among Aymara.

Hormone Measures in Finger-Prick Blood Spot Samples: New Field Methods for Reproductive Endocrinology

Comparative endocrine studies have notably advanced understanding of ecological factors that contribute to variation in human reproductive function. Such research has relied on methodological advances that permit hormone determinations in samples that are easily and safely collected, stored, and transported, most recently on measurement of steroids in saliva. This report seeks to further expand the scope of endocrine research by demonstrating the value of blood spot samples collected by finger prick. As a sampling strategy, finger-prick blood spot collection offers the advantages of short collection time, low invasiveness, repeatability, absence of postcollection processing, low biohazard risk, and ease of sample storage and transport. We document good sample stability and present sensitive assay methods for a range of steroids and proteins (FSH, LH, PRL, T, E2, DHEAS, androstenedione, cortisol, SHGB) in blood spots that require sample volumes of 3-12 microliters and display good reliability, specificity, precision, accuracy, and convertibility of results to plasma/serum equivalent concentrations. Laboratory evaluation was augmented by a feasibility study at a remote site in Papua New Guinea that confirmed validity and stability of blood spot collections under field conditions. Research applications of blood spot sampling are illustrated with a series of studies, including cross-sectional surveys for developmental and life span endocrinology, a longitudinal, population-based developmental epidemiologic study of puberty, and serial sampling in a dynamic study of neuroendocrine response to suckling. We conclude that the sampling features and wide range of measurable biomolecules of blood spots do constitute a methodological advance for endocrine research.

Epstein-barr virus antibodies in whole blood spots: A minimally invasive method for assessing an aspect of cell-mediated immunity

Objective Study 1: Introduce and validate a method for measuring EBV p18-VCA antibodies in whole blood spots to provide a minimally invasive marker of cell-mediated immune function. Study 2: Apply this method to a large community-based study of psychopathology in children and adolescents. Methods The EBV antibody method was evaluated through analysis of precision, reliability, stability, and comparisons with plasma and indirect immunofluorescence methods. The effects of life events on p18-VCA antibody level were considered in a subsample of 9, 11, and 13 year-old children participating in the Great Smoky Mountains Study in North Carolina. The subsample was stratified by age, sex, and degree of overall life strain. Results Dried blood spots provided a convenient, sensitive, precise, and reliable method for measuring EBV p18-VCA antibody titer. Life events were positively associated with p18-VCA antibodies in girls but not in boys. Conclusions The validity of the blood spot EBV p18-VCA antibody assay, as well as the ease of sample collection, storage, and transportation, may provide an opportunity for psychoneuroimmunology to explore a wider range of stress models in larger, community-based studies.