Measuring Puberty and Understanding Its Impact: A Longitudinal Study of Adolescent Twins

DNA methylation sites in early adulthood characterised by pubertal timing and development: a twin study

BACKGROUND

Puberty is a highly heritable and variable trait, with environmental factors having a role in its eventual timing and development. Early and late pubertal onset are both associated with various diseases developing later in life, and epigenetic characterisation of pubertal timing and development could lead to important insights. Blood DNA methylation, reacting to both genotype and environment, has been associated with puberty; however, such studies are relatively scarce. We investigated peripheral blood DNA methylation profiles (using Illumina 450 K and EPIC platforms) of 1539 young adult Finnish twins associated with pubertal development scale (PDS) at ages 12 and 14 as well as pubertal age (PA).

RESULTS

Fixed effect meta-analysis of the two platforms on 347,521 CpGs in common identified 58 CpG sites associated (p < 1 × 10-5) with either PDS or PA. All four CpGs associated with PA and 45 CpGs associated with PDS were sex-specific. Thirteen CpGs had a high heritability (h2: 0.51-0.98), while one CpG site (mapped to GET4) had a high shared environmental component accounting for 68% of the overall variance in methylation at the site. Utilising twin discordance analysis, we found 6 CpG sites (5 associated with PDS and 1 with PA) that had an environmentally driven association with puberty. Furthermore, genes with PDS- or PA-associated CpGs were consistently linked to various developmental processes and diseases such as breast, prostate and ovarian cancer, while methylation quantitative trait loci of associated CpG sites were enriched in immune pathways developing during puberty.

CONCLUSIONS

By identifying puberty-associated DNA methylation sites and examining the effects of sex, environment and genetics, we shed light on the intricate interplay between environment and genetics in the context of puberty. Through our comprehensive analysis, we not only deepen the understanding of the significance of both genetic and environmental factors in the complex processes of puberty and its timing, but also gain insights into potential links with disease risks.

The Association Between Puberty Timing and Body Mass Index in a Longitudinal Setting: The Contribution of Genetic Factors

We analyzed the contribution of genetic factors on the association between puberty timing and body mass index (BMI) using longitudinal data and two approaches: (i) genetic twin design and (ii) polygenic scores (PGS) of obesity indices. Our data were derived from Finnish cohorts: 9080 twins had information on puberty timing and BMI and 2468 twins also had genetic data. Early puberty timing was moderately associated with higher BMI in childhood in both boys and girls; in adulthood these correlations were weaker and largely disappeared after adjusting for childhood BMI. The largest proportion of these correlations was attributable to genetic factors. The higher PGSs of BMI and waist circumference were associated with earlier timing of puberty in girls, whereas weaker associations were found in boys. Early puberty is not an independent risk factor for adult obesity but rather reflects the association between puberty timing and childhood BMI contributed by genetic predisposition.

The onset of pubertal development and actigraphy-assessed sleep during middle childhood: Racial, gender, and genetic effects

OBJECTIVE

This study (1) examined pubertal development in relation to actigraphy-assessed sleep in twin children, and tested whether associations differed by child race and gender, (2) modeled genetic and environmental influences on pubertal development and sleep indicators, and (3) examined genetic and environmental influences on the covariation of puberty and sleep.

DESIGN

The classic twin design was used to examine genetic and environmental contributions to puberty and sleep and their associations.

SETTING

Data were collected from community-dwelling urban and rural families of twins in the southwestern U.S.

PARTICIPANTS

The racially and socioeconomically diverse sample included 596 twin children (M_age = 8.41, SD = 0.69; 51.7% female; 66.3% white; 33.7% Hispanic; 170 monozygotic, 236 same-sex dizygotic, 188 opposite-sex dizygotic).

MEASUREMENTS

Pubertal development was assessed via parent report. Children wore actigraph watches for 7 nights (M = 6.81, SD = 0.67) to capture sleep duration, efficiency, midpoint, onset latency, and duration variability.

RESULTS

In contrast to extant literature with older youth, more advanced pubertal development was associated with longer sleep durations in Hispanic and white girls and higher sleep efficiency in white girls, though Hispanic girls demonstrated later sleep midpoints. Pubertal development was moderately heritable and there was a genetic influence on the covariance between puberty and sleep indicators.

CONCLUSIONS

This was the first study to examine the genetic and environmental influences on the covariation between puberty and sleep, and found genetic underpinnings between pubertal development and actigraphy-assessed sleep duration and efficiency, though sleep and puberty were almost entirely independent in twins at this age.

Longitudinal Associations of Pubertal Timing and Tempo With Adolescent Mental Health and Risk Behavior Initiation in Urban South Africa

PURPOSE

In high-income countries, early and rapid pubertal development is consistently associated with poor adjustment and increased risk behavior in adolescence. This study contributes to the meager knowledge of these associations in lower income countries.

METHODS

We used longitudinal data from 1,784 urban black South Africans in the Birth to Twenty Plus cohort. We used regression analyses to assess associations between age at menarche and latent classes of pubertal timing and tempo and adolescent internalizing and externalizing emotional and behavioral problems, eating attitudes, and patterns of health risk behavior initiation.

RESULTS

Relatively earlier and faster pubertal timing and tempo were associated with increased health risk behavior initiation (e.g., adjusted odds ratio [95% confidence interval] high- vs. low-risk pattern = 5.7 [1.7, 19.06] for male genital development; adjusted odds ratio = 3.45 [1.13, 10.49] for female breast development). Among males, earlier and faster pubertal timing and tempo were associated with increased externalizing problems in early adolescence and increased oppositional defiant problems in midadolescence, whereas later and slower pubertal timing and tempo were associated with decreases. Among females, earlier and faster pubertal timing and tempo were associated with increased internalizing and externalizing problems in midadolescence and increased dieting behaviors in early and late adolescence (β [95% confidence interval] = 2.51 [.87, 4.15] for pubic hair development), whereas later and slower pubertal timing and tempo were associated with decreases.

CONCLUSIONS

In this urban South African cohort, relatively earlier and faster pubertal development was detrimental to mental health and risk behavior activity, whereas later and slower maturation was somewhat protective.

Pubertal Timing and Substance use in Adolescence: an Investigation of Two Cognitive Moderators

Off-time pubertal development is a predictor of substance use among adolescents. Early-maturing girls and early- and late-maturing boys appear to be at greater risk for substance use, although findings are more consistent for girls. Although cognitive factors are also important in the etiology of adolescent substance use, few studies have investigated potential cognitive risk and protective factors in these associations. The current study tested whether future orientation or cognitive style (e.g., attributions youth make about the causes and consequences of negative life events) moderated the association between pubertal timing and substance use two years later and whether this effect was stronger for females. Multiple linear regressions revealed cognitive style and future orientation significantly moderated the association between pubertal timing and substance use, and these effects did not differ by sex. Importantly, the pattern of these interactions differed, such that early pubertal timing predicted more substance use in the context of more negative and moderate cognitive styles and greater and moderate future orientation. Follow-up analyses revealed that an adolescent's attributions about the consequences, globality, and self-worth implications of negative life events significantly moderated the pubertal timing - future substance use association. Furthermore, the pattern of these interactions predicted each of the four types of substances assessed in the context of cognitive style, but only predicted nicotine and marijuana use in the context of future orientation. These results highlight which cognitive factors may influence risk for substance use for early-maturing youth.

Longitudinal associations of physical activity and pubertal development with academic achievement in adolescents

OBJECTIVE

We sought to investigate the longitudinal associations of moderate-to-vigorous physical activity (MVPA) and pubertal development with academic achievement in adolescents.

METHODS

A total of 635 adolescents (283 boys, 352 girls) aged 11-13 years participated in the study. MVPA was assessed by the Health Behaviour in School-aged Children study questionnaire, and pubertal development was assessed by the Pubertal Development Scale at beginning of the 6th grade (baseline) and end of the 7th grade (follow-up). Grade point average (GPA) at the end of Grades 5 and 7 was computed from data acquired from the school registers. The data were analyzed using linear regression and analyses of covariance.

RESULTS

In boys, MVPA was positively associated with GPA at baseline after adjustment for age (β = 0.144, 95% confidence interval (CI): 0.028-0.260, p = 0.028). In girls, the Pubertal Development Scale was positively associated with GPA at baseline (β = 0.104, 95%CI: -0.004 to 0.211, p = 0.058) and follow-up (β = 0.104, 95%CI: -0.002 to 0.211, p = 0.055) after adjustment for age, and these associations strengthened after further adjustment for MVPA (p < 0.05). Adolescents who were inactive at baseline or at baseline and follow-up had lower GPA during follow-up than their continuously highly active peers (mean difference = -0.301, 95%CI: -0.543 to -0.058, p = 0.009) and all other adolescents (mean difference = -0.247, 95%CI: -0.475 to -0.019, p = 0.029). These differences were greater in girls than in boys.

CONCLUSION

Lower levels of MVPA were associated with lower GPA in boys at baseline. Girls who were continuously inactive had lower GPA over the follow-up period than those who were continuously active. Finally, earlier pubertal development was associated with better academic achievement in girls.

Polygenic Influences on Pubertal Timing and Tempo and Depressive Symptoms in Boys and Girls

This study used polygenic scoring (PGS) to test whether puberty-related genes were correlated with depressive symptoms, and whether there were indirect effects through pubertal maturation. The sample included 8,795 adolescents from the Avon Longitudinal Study of Parents and Children (measures of puberty drawn ages 8-17 years; of depressive symptoms at age 16.5 years). The PGS (derived from a genome-wide meta-analysis of later age at menarche) predicted boys' and girls' later pubertal timing, boys' slower gonadal development, and girls' faster breast development. Earlier perceived breast development timing predicted more depressive symptoms in girls. Findings support shared genetic underpinnings for boys' and girls' puberty, contributing to multiple pubertal phenotypes with differences in how these genetic variants affect boys' and girls' development.

Correspondence of Pubertal Neuroendocrine and Tanner Stage Changes in Boys and Associations With Substance Use

This study examined correspondence between timing (onset) and tempo (rate) of sexual maturation prospectively (average ages 11-16 years) measured by gonadal hormones and secondary sex characteristics (Tanner stage) using dual-process models, and associations of these measures with substance use (SU) involvement in boys at age 16 years (N = 534, 77.5% White/22.5% Non-White). All measures of timing were highly associated. Early Tanner stage timing often predicted slower increases in gonadal steroids, but not the reverse; patterns varied by ethnicity. Hormone and Tanner stage measures were similar earlier in development but diverged later in development. In White boys only, early timing of the pubertal rise in testosterone was associated with increased SU involvement, suggesting a physiological rather than psychosocial mechanism of association.

FinnTwin12 Cohort: An Updated Review

This review offers an update on research conducted with FinnTwin12 (FT12), the youngest of the three Finnish Twin Cohorts. FT12 was designed as a two-stage study. In the first stage, we conducted multiwave questionnaire research enrolling all eligible twins born in Finland during 1983-1987 along with their biological parents. In stage 2, we intensively studied a subset of these twins with in-school assessments at age 12 and semistructured poly-diagnostic interviews at age 14. At baseline, parents of intensively studied twins were administered the adult version of the interview. Laboratory studies with repeat interviews, neuropsychological tests, and collection of DNA were made of intensively studied twins during follow-up in early adulthood. The basic aim of the FT12 study design was to obtain information on individual, familial and school/neighborhood risks for substance use/abuse prior to the onset of regular tobacco and alcohol use and then track trajectories of use and abuse and their consequences into adulthood. But the longitudinal assessments were not narrowly limited to this basic aim, and with multiwave, multirater assessments from ages 11 to 12, the study has created a richly informative data set for analyses of gene-environment interactions of both candidate genes and genomewide measures with measured risk-relevant environments. Because 25 years have elapsed since the start of the study, we are planning a fifth-wave follow-up assessment.

11-year old boy with facial hair, acne and deepened voice

11-year old twin boy found to have idiopathic precocious puberty after routine well-child examination revealed discordant pubertal growth between the two brothers.

Association between Vitamin D Receptor Polymorphism and Serum Vitamin D Levels in Children with Low-Energy Fractures

OBJECTIVE

Fractures of bones, especially forearm fractures, are very common in children and their number is increasing. This study was designed to determine the impact of vitamin D serum levels and vitamin D receptor (VDR) polymorphisms on the occurrence of low-energy fractures in children.

METHODS

The study group consisted of 100 children with clinically relevant bone fractures and a control group consisted of 127 children without fractures. Total vitamin D [25(OH)D3 plus 25(OH)D2] serum concentrations were evaluated in every patient. Genotypes for 4 restriction fragment length polymorphisms of the vitamin D receptor gene (FokI, ApaI, TaqI, and BsmI) were determined by standard polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques.

RESULTS

Differences in concentrations of vitamin D were observed between the group with bone fractures (median = 12 ng/ml) and the control group (median = 16 ng/ml; p = 0.000044). Higher levels of vitamin D reduced the risk of fracture by 1.06 times (p = 0.0005). No impact of particular VDR polymorphism on the occurrence of low-energy fractures in children was detected. However, there were significant differences in the prevalence of FokI polymorphism genotypes between the fracture and control groups (p = 0.05). Furthermore, the recessive "aa" genotype of ApaI polymorphism and the dominant "TT" genotype of TaqI polymorphism were associated with higher levels of vitamin D (p = 0.005 and p = 0.036, respectively).

CONCLUSIONS

Vitamin D deficiency is an independent risk factor for fractures in children. ApaI polymorphism recessive "aa" and TaqI polymorphism dominant "TT" genotypes are associated with higher levels of vitamin D in serum.

Parental Knowledge is a Contextual Amplifier of Associations of Pubertal Maturation and Substance Use

Earlier pubertal development and less parental knowledge have been linked to more substance use during adolescence. The present study examines interactions between pubertal timing and tempo and parental knowledge (children's disclosure, parental control, and parental solicitation) for adolescent substance initiation. Data are from a northeastern US-based cohort-sequential study examining 1023 youth (52 % female) semiannually for up to 6 assessments (ages 10.5-19 years). The findings supported the hypothesis that lower knowledge is a contextual amplifier of early timing-substance use associations in girls and later timing/slower tempo-substance use associations in boys, though results varied based on source of knowledge. The findings suggest that prevention efforts may have the greatest impact when targeting families of early developing girls, and later developing boys, and that incorporating a focus on specific sources of knowledge depending on the pubertal maturation profile of the adolescent may prove valuable in prevention/intervention efforts.

Genetic and Environmental Contributions to Covariation Between DHEA and Testosterone in Adolescent Twins

Although several studies have shown that pubertal tempo and timing are shaped by genetic and environmental factors, few studies consider to what extent endocrine triggers of puberty are shaped by genetic and environmental factors. Doing so moves the field from examining correlated developmentally-sensitive biomarkers toward understanding what drives those associations. Two puberty related hormones, dehydroepiandrosterone and testosterone, were assayed from salivary samples in 118 MZ (62 % female), 111 same sex DZ (46 % female) and 103 opposite-sex DZ twin pairs, aged 12-16 years (M = 13.1, SD = 1.3). Pubertal status was assessed with a composite of mother- and self-reports. We used biometric models to estimate the genetic and environmental influences on the variance and covariance in testosterone and DHEA, with and without controlling for their association with puberty, and to test for sex differences. In males, the variance in testosterone and pubertal status was due to shared and non-shared environmental factors; variation in DHEA was due to genetic and non-shared environmental factors. In females, variance in testosterone was due to genetic and non-shared environmental factors; genetic, shared, and non-shared environmental factors contributed equally to variation in DHEA. In males, the testosterone-DHEA covariance was primarily due to shared environmental factors that overlapped with puberty as well as shared and non-shared environmental covariation specific to testosterone and DHEA. In females, the testosterone-DHEA covariance was due to genetic factors overlapping with pubertal status, and shared and non-shared environmental covariation specific to testosterone and DHEA.

Moderators of the association between peer and target adolescent substance use

Associating with substance using peers is generally considered as one of the most important predictors of adolescent substance use. However, peer association does not affect all adolescents in the same way. To better understand when and under what conditions peer association is most linked with adolescent substance use (SU), this review focuses on the factors that may operate as moderators of this association. The review highlighted several potential moderators reflecting adolescents' individual characteristics (e.g., pubertal status, genes and personality), peer and parental factors (e.g., nature of relationships and parental monitoring), and contextual factors (e.g., peer, school and neighborhood context). As peer association is a broad concept, important methodological aspects were also addressed in order to illustrate how they can potentially bias interpretation. Taking these into account, we suggest that, while the effects of some moderators are clear (e.g., parental monitoring and sensation seeking), others are less straightforward (e.g., neighborhood) and need to be further examined. This review also provides recommendations for addressing different methodological concerns in the study of moderators, including: the use of longitudinal and experimental studies and the use of mediated moderation. These will be key for developing theory and effective prevention.

Association of height and pubertal timing with lipoprotein subclass profile: exploring the role of genetic and environmental effects

OBJECTIVES

Little is known about the relationship between growth and lipoprotein profile. We aimed to analyze common genetic and environmental factors in the association of height from late childhood to adulthood and pubertal timing with serum lipid and lipoprotein subclass profile.

METHODS

A longitudinal cohort of Finnish twin pairs (FinnTwin12) was analyzed using self-reported height at 11-12, 14, 17 years and measured stature at adult age (21-24 years). Data were available for 719 individual twins including 298 complete pairs. Serum lipids and lipoprotein subclasses were measured by proton nuclear magnetic resonance spectroscopy. Multivariate variance component models for twin data were fitted. Cholesky decomposition was used to partition the phenotypic covariation among traits into additive genetic and unique environmental correlations.

RESULTS

In men, the strongest associations for both adult height and puberty were observed with total cholesterol, low-density lipoprotein cholesterol, intermediate-density lipoprotein cholesterol, and low-density lipoprotein particle subclasses (max. r = -0.19). In women, the magnitude of the correlations was weaker (max. r = -0.13). Few associations were detected between height during adolescence and adult lipid profile. Early onset of puberty was related to an adverse lipid profile, but delayed pubertal development in girls was associated with an unfavorable profile, as well. All associations were mediated mainly by additive genetic factors, but unique environmental effects cannot be disregarded.

CONCLUSIONS

Early puberty and shorter adult height relate to higher concentrations of atherogenic lipids and lipoprotein particles in early adulthood. Common genetic effects behind these phenotypes substantially contribute to the observed associations.

Testing whether and when parent alcoholism uniquely affects various forms of adolescent substance use

The current study examined the distal, proximal, and time-varying effects of parents' alcohol-related consequences on adolescents' substance use. Previous studies show that having a parent with a lifetime diagnosis of alcoholism is a clear risk factor for adolescents' own substance use. Less clear is whether the timing of a parent's alcohol-related consequences differentially predicts the adolescent's own substance involvement. Using a multilevel modeling approach, we tested whether adolescents showed elevated rates of alcohol, heavy alcohol, marijuana and other illegal drug use (a) at the same time that parents showed alcohol-related consequences (time-varying effects), (b) if parents showed greater alcohol-related consequences during the child's adolescence (proximal effects), and (c) if parents had a lifetime diagnosis of alcoholism that predated the child's adolescence (distal effects). We tested these effects in a high-risk sample of 451 adolescents assessed over three waves beginning at ages 11-15 from 1988 to 1991 (53 % male, 71 % non-Hispanic Caucasian, 54 % children of alcoholic parents and 46 % matched controls). Strong and consistent distal effects of parent alcoholism on adolescent's substance use were found, though no additional risk was associated with proximal effects. Limited time-varying effects were also found. The importance of differentiating the timing effects of parent alcoholism in identifying underlying mechanisms of risk for adolescent substance use is discussed.

A systematic review of the relationships between family functioning, pubertal timing and adolescent substance use

AIMS

Experiences linked to poor family functioning and pubertal timing have each been associated with increased risk of substance misuse in adolescence. However, it remains unclear to what extent family functioning and pubertal timing combine to put adolescents at particular risk.

METHOD

A systematic review was planned, undertaken and reported according to the 27 items of the PRISMA statement. Databases World of Knowledge, PsycINFO and PubMed were searched. Fifty-eight papers were retained and are discussed in this review after screening titles, abstracts and full papers against pre-established exclusion criteria.

RESULTS

The combination of off-time pubertal timing and poor parent-adolescent relationship quality has been related to higher levels of substance use. However, this is an under-studied area of research and the evidence is less strong for boys than girls.

CONCLUSIONS

Adolescents experiencing both poor parent-adolescent relationship quality and off-time pubertal timing may represent a high-risk group that can benefit from approaches aimed at reducing risk of substance misuse.

Pubertal maturation and sex steroids are related to alcohol use in adolescents

Adolescents often show risk-taking behavior, including experimentation with alcohol. Previous studies have shown that advanced pubertal maturation is related to increased alcohol use in adolescents, even when controlling for age. Little is known about the underlying mechanisms of this relation between pubertal maturation and alcohol use. The goal of the present study was twofold. In Experiment 1, we investigated whether advanced pubertal maturation is associated with higher levels of alcohol use, when controlling for age. To this end, questionnaires on pubertal development and alcohol use were administered to a large sample of 797 Dutch adolescents (405 boys) aged 11-16 years. In Experiment 2, we explored whether sex steroids contribute to this relation between pubertal maturation and alcohol use by examining the association between salivary sex steroid levels and alcohol use in 168 adolescents (86 boys). It was found that, when controlling for age, advanced pubertal maturation is related to increased alcohol use in adolescent boys and girls. Controlling for age, higher testosterone and estradiol levels correlated with the onset of alcohol use in boys. In addition, higher estradiol levels were associated with a larger quantity of alcohol use in boys. Correlations between sex steroids and alcohol use were not significant in girls. These findings show that advanced pubertal maturation is related to advanced alcohol use, and that higher sex steroid levels could be one of the underlying mechanisms of this relation in boys. Sex steroids might promote alcohol use by stimulating brain regions implicated in reward processing.

Contributions of circadian tendencies and behavioral problems to sleep onset problems of children with ADHD

BACKGROUND

Children with attention-deficit/hyperactivity disorder (ADHD) are two to three times more likely to experience sleep problems. The purpose of this study is to determine the relative contributions of circadian preferences and behavioral problems to sleep onset problems experienced by children with ADHD and to test for a moderation effect of ADHD diagnosis on the impact of circadian preferences and externalizing problems on sleep onset problems.

METHODS

After initial screening, parents of children meeting inclusion criteria documented child bedtime over 4 nights, using a sleep log, and completed questionnaires regarding sleep, ADHD and demographics to assess bedtime routine prior to PSG. On the fifth night of the study, sleep was recorded via ambulatory assessment of sleep architecture in the child's natural sleep environment employing portable polysomnography equipment. Seventy-five children (26 with ADHD and 49 controls) aged 7-11 years (mean age 8.61 years, SD 1.27 years) participated in the present study.

RESULTS

In both groups of children, externalizing problems yielded significant independent contributions to the explained variance in parental reports of bedtime resistance, whereas an evening circadian tendency contributed both to parental reports of sleep onset delay and to PSG-measured sleep-onset latency. No significant interaction effect of behavioral/circadian tendency with ADHD status was evident.

CONCLUSIONS

Sleep onset problems in ADHD are related to different etiologies that might require different interventional strategies and can be distinguished using the parental reports on the CSHQ.

Pubertal testosterone predicts mental rotation performance of young adult males

Robust sex differences in some spatial abilities that favor males have raised the question of whether testosterone contributes to those differences. There is some evidence for prenatal organizational effects of testosterone on male-favoring spatial abilities, but not much is known about the role of pubertal testosterone levels on adult cognitive abilities. We studied the association between pubertal testosterone (at age 14) and cognitive performance in young adulthood (at age 21-23), assessing male-favoring, female-favoring, and sex-neutral cognitive domains in a population-based sample of 130 male and 178 female twins. Pubertal testosterone was negatively associated with performance in the Mental Rotation Test in young adult men (r=-.27), while among women no significant associations between testosterone and cognitive measures were detected. The significant association among men remained after controlling for pubertal development. Confirmatory within-family comparisons with one-sided significance testing yielded a negative correlation between twin pair differences in testosterone levels and Mental Rotation Test performances in 35 male twin pairs (r=-.32): the twin brother with higher testosterone performed less well on the Mental Rotation Test. That association was evident in 18 pairs of dizygotic male twin pairs (r=-.42; analysis controlling for shared environmental effects). In contrast, the association of differences was not evident among 17 monozygotic male twin pairs (r=-.07; analysis controlling for shared genetic influences). Results suggest that pubertal testosterone levels are related specifically to male-favoring spatial ability and only among men. Within-family analyses implicated possible shared genetic effects between pubertal testosterone and mental rotation ability.

Genetic and environmental influences on the association between pubertal maturation and internalizing symptoms

The literature consistently shows an association between pubertal maturation and internalizing problems in girls. The association for boys is less clear. The present study examines genetic and environmental influences on the association between pubertal maturation and internalizing problems for boys and girls in two primarily Caucasian adolescent twin/sibling studies: The Swedish Twin study of CHild and Adolescent Development (706 same-sex twin pairs aged 13-14, M = 13.7 years, 50 % female), and the Nonshared Environment in Adolescent Development sample (US-based, 687 same-sex twin/sibling pairs aged 10-18, M = 13.6 years, 47 % female). For girls, more advanced pubertal maturation was associated modestly with more internalizing problems, and that association was entirely explained by shared environmental influences. For boys, the association between pubertal maturation and internalizing problems was weak and inconsistent. Results for girls were remarkably consistent across samples. Findings suggest that nongenetic mechanisms mediate the association between pubertal maturation and internalizing problems. Findings have implications for intervention such that environmental influences shared by twins/siblings may provide the best targets for intervention strategies designed to minimize the potential negative effects of pubertal maturation on internalizing symptoms in girls.

The stability of perceived pubertal timing across adolescence

It is unknown whether perceived pubertal timing changes as puberty progresses or whether it is an important component of adolescent identity formation that is fixed early in pubertal development. The purpose of this study is to examine the stability of perceived pubertal timing among a school-based sample of rural adolescents aged 11-17 (N=6,425; 50% female; 53% White). Two measures of pubertal timing were used, stage-normative, based on the Pubertal Development Scale, a self-report scale of secondary sexual characteristics, and peer-normative, a one-item measure of perceived pubertal timing. Two longitudinal methods were used: one-way random effects ANOVA models and latent class analysis. When calculating intraclass correlation coefficients using the one-way random effects ANOVA models, which is based on the average reliability from one time point to the next, both measures had similar, but poor, stability. In contrast, latent class analysis, which looks at the longitudinal response pattern of each individual and treats deviation from that pattern as measurement error, showed three stable and distinct response patterns for both measures: always early, always on-time, and always late. Study results suggest instability in perceived pubertal timing from one age to the next, but this instability is likely due to measurement error. Thus, it may be necessary to take into account the longitudinal pattern of perceived pubertal timing across adolescence rather than measuring perceived pubertal timing at one point in time.

Pubertal development moderates the importance of environmental influences on depressive symptoms in adolescent girls and boys

Prevalence differences in depressive symptoms between the sexes typically emerge in adolescence, with symptoms more prevalent among girls. Some evidence suggests that variation in onset and progression of puberty might contribute to these differences. This study used a genetically informative, longitudinal (assessed at ages 12, 14, and 17) sample of Finnish adolescent twins (N = 1214, 51.6% female) to test whether etiological influences on depressive symptoms differ as a function of pubertal status. These tests were conducted separately by sex, and explored longitudinal relationships. Results indicated that pubertal development moderates environmental influences on depressive symptoms. These factors are more important on age 14 depressive symptoms among more developed girls relative to their less developed peers, but decrease in influence on age 17 depressive symptoms. The same effects are observed in boys, but are delayed, paralleling the delay in pubertal development in boys compared to girls. Thus, the importance of environmental influences on depressive symptoms during adolescence changes as a function of pubertal development, and the timing of this effect differs across the sexes.

The Relationship between Pubertal Timing and Delinquent Behavior in Maltreated Male and Female Adolescents

This study examined the relationship between pubertal timing and delinquent behavior across two time points in a sample of 303 maltreated and 151 comparison adolescents aged 9-13 years at enrollment. The first aim was to examine the relationship between pubertal timing and delinquency for the total sample and then to test for gender differences using multiple-group models. The second aim was to examine the interaction effect of pubertal timing and maltreatment on delinquency as well as gender differences for this interaction effect. Results showed that earlier pubertal timing was related to higher delinquency and this relationship was not significantly different for males and females. Maltreatment did not moderate the relationship between pubertal timing and delinquency for the total sample; however, there was evidence of a three-way interaction. These findings highlight the need to examine contextual factors that may affect the amplification and direction of these relationships.

Leisure activity patterns and their associations with overweight: a prospective study among adolescents

We examined longitudinal associations between individual leisure activities (television viewing, video viewing, computer games, listening to music, board games, musical instrument playing, reading, arts, crafts, socializing, clubs or scouts, sports, outdoor activities) and being overweight using logistic regression and latent class analysis in a cohort of Finnish twins responding to self-report questionnaires at 11-12 (N=5184), 14, and 17 years. We also studied activity patterns ("Active and sociable", "Active but less sociable", "Passive but sociable", "Passive and solitary") thought to represent different lifestyles. Among boys, activity patterns did not predict becoming overweight, but sports and playing an instrument reduced the risk and arts and listening to music increased it. Among girls, few individual leisure activities predicted becoming overweight. However, girls in the "Passive and solitary" cluster carried the greatest risk of becoming overweight in late adolescence. Studying leisure activities related to overweight may help focus specific interventions on high risk groups.

Genetic and environmental influences on pubertal timing assessed by height growth

Secular trends towards earlier puberty, possibly caused by new environmental triggers, provide a basis for periodic evaluation of the influence and interaction of genetic and environmental effects on pubertal timing. In such studies, a practical marker that reflects timing of puberty in both genders needs to be used. We investigated genetic and environmental influences on pubertal timing by using change in the relative height between early and late adolescence (HD:SDS, height difference in standard deviations) as a new marker of pubertal timing. HD:SDS correlated well with age at peak height velocity in a population of men and women with longitudinal growth data. In 2,309 twin girls and 1,828 twin boys, HD:SDS was calculated between height SDs at age 11.5 and 17.5, and 14.0 and 17.5 years, respectively. Quantitative genetic models for twin data were fitted to estimate the genetic contribution to HD:SDS. We also investigated whether the same genetic factors influenced individual differences between HD:SDS and development of secondary sex characteristics prospectively collected by pubertal development scale (PDS). Genetic effects contributed to 86 and 82% of the variance in HD:SDS in girls and boys, respectively, when using the same model including additive genetic and specific environmental factors. In girls, 30% and in boys, 49% of the genetic factors affecting PDS and HD:SDS were the same. Future comparison of the results of periodic evaluations allows estimation of possible changes in the effects of environment on timing of puberty. In such studies, HD:SDS can be used as a practical marker of pubertal timing.

Family environments, adrenarche, and sexual maturation: a longitudinal test of a life history model

Life history theorists have proposed that humans have evolved to be sensitive to specific features of early childhood environments and that exposure to different environments biases children toward development of different reproductive strategies, including differential pubertal timing. The current research provides a longitudinal test of this theory. Assessments of family environments, based on interviews with mothers and fathers, were conducted in preschool, and children were then followed prospectively through middle childhood. Adrenal hormones were assayed in a selected subsample of 120 children (73 girls) at age 7, and parent and child reports of secondary sexual characteristics were collected in the full female sample of 180 girls at age 11. Higher quality parental investment (from both mothers and fathers) and less father-reported Marital Conflict/Depression forecast later adrenarche. Older age at menarche in mothers, higher socioeconomic status, greater mother-based Parental Supportiveness, and lower third-grade body mass index each uniquely and significantly predicted later sexual development in daughters. Consistent with a life history perspective, quality of parental investment emerged as a central feature of the proximal family environment in relation to pubertal timing.

Detrimental Psychological Outcomes Associated with Early Pubertal Timing in Adolescent Girls

Though often discussed as though it were a discrete event, puberty comprises one segment of a larger developmental continuum and is notable for rapid transformation across a multitude of domains. Research suggests that an earlier rate of pubertal maturation in girls correlates with a number of detrimental outcomes compared with on-time or later maturation. The present review synthesizes the research on negative psychological sequelae of early pubertal timing in adolescent girls. Emphasis is on three theoretical perspectives by which precocious development is believed to affect the emergence of adverse outcomes: biological, psychosocial, and selection effects.

Pubertal maturation and the development of alcohol use and abuse

OBJECTIVE

To examine the impact of various aspects of puberty on risk of using alcohol and developing alcohol use disorder (AUD).

METHODS

Data come from the Great Smoky Mountains Study, a longitudinal study of a representative sample of 1420 youth aged 9-13 at recruitment. Participants were interviewed annually to age 16. A parent was also interviewed. Information was obtained about use of a range of drugs including alcohol, drug abuse and dependence, other psychiatric disorders, life events, and a wide range of family characteristics. Pubertal hormones were assayed annually from blood samples, and morphological development was assessed using a pictorial measure of Tanner stage.

RESULTS

Controlling for age, Tanner stage predicted alcohol use and AUD in both boys (OR 1.58, 95% CI 1.18-2.22) and girls (OR 1.62, 95% CI 1.17-2.23). The effect of morphological development was strongest in those who matured early. Early pubertal maturation predicted alcohol use in both sexes, and AUD in girls. The highest level of excess risk for alcohol use was seen in early maturing youth with conduct disorder and deviant peers. Lax supervision predicted alcohol use in early maturing girls, while poverty and family problems were predictive in early maturing boys.

CONCLUSIONS

Among the many biological, morphological, and social markers of increasing maturation, the visible signs of maturity are important triggers of alcohol use and AUD, especially when they occur early and in young people with conduct problems, deviant peers, problem families and inadequate parental supervision.

Precocious puberty in adolescent girls: a biomarker of later psychosocial adjustment problems

We have investigated the hypothesis that stress condition will accelerate pubertal maturation in adolescent girls and that faster maturing girls will display more behavioral problems than their on-time or late-maturing peers during pubertal development. Longitudinal data were collected yearly from 1986 to 1997. Parents of 1039 French-speaking Canadian girls completed a questionnaire about their characteristics as well as those of their family. To predict onset of puberty by time and cumulative risk factors, a Hierarchical Regression Analysis and a Survival Regression Analysis were conducted. Results revealed that: (1) anxiety at 8 years old, lower level of anxiety a year earlier and more adverse family condition predict a younger age at first menses; and (2) Body Mass Index, conflicts, and sleep disturbances significantly predict the onset of puberty. Complementary standard regression analyses demonstrated that situational stress mediated the effect of these variables. We concluded that precocious puberty could be an indicator of stress in a child, thus, allowing professionals to intervene early and to prevent later problems in psychosocial adjustment.

Genetic and environmental influences on age at sexual initiation in the Colorado Adoption Project

Whereas the majority of research on adolescent sexual initiation has focused solely on environmental factors, the present study used behavioral genetic analyses to investigate the relative contributions of genetic and environmental influences. Structural equation models were fitted to data from adoptive and non-adoptive sibling pairs (231 biologically related pairs and 169 unrelated pairs) from the Colorado Adoption Project. Information from censored individuals who had not yet experienced sexual initiation was maximized by adapting the twin survival analysis method of Pickles et al. (Behav Genet 24(5):457-468, 1994) to accommodate adoptive and non-adoptive siblings. Point estimates of variance components from an ACE model, including additive genetic (A), shared environmental (C), and non-shared environmental (E) influences were 28%, 24%, and 48%, respectively. Despite the lower point estimate for shared environmental effects than additive genetic effects, a CE model provided the best fit to the data. However, because adoptive siblings provide a direct estimate of shared environmental influences there is greater power to detect shared environmental effects in adoption designs. Evidence for genetic influences from our data were somewhat lower than those obtained in previous twin studies, possibly reflecting a return to more socially conservative sexual attitudes, changing sexual behaviors, or ambiguities in the wording of questions commonly used in research on adolescent sexuality.

Testosterone and alcohol use among adolescent male twins: testing between-family associations in within-family comparisons

We examined associations of testosterone (T) and alcohol use in adolescent twin brothers, conducting both between- and within-family analyses. The twins completed semi-structured interviews, provided two saliva samples to assay T, and reported their drinking patterns and pubertal development. We adjusted T levels for diurnal/seasonal effects and association with pubertal maturation. In analyses of twins as individuals, higher T levels characterized boys reporting ever drinking, more frequent intoxication, high density drinking, more alcohol symptoms, and diagnosed alcohol dependency on interview. Adjusting for pubertal development, only associations with symptom count and diagnosis remained significant. The association with frequent intoxication replicated among drinking-discordant twin brothers, effectively ruling out between-family confounds, but that association was not significant after adjustment for pubertal development. The phenotypic correlation between T and pubertal maturation is largely genetic, inviting study of the magnitude and meaning of linkages between testosterone and symptoms of alcoholism on follow-up in early adulthood.

Sexual maturation in early adolescence and alcohol drinking and cigarette smoking in late adolescence: a prospective study of 2,129 Norwegian girls and boys

Early sexual maturation has been associated with higher involvement in risk behaviour during early and mid-adolescence. In a prospective study of 2,129 girls and boys, we investigated whether the timing of sexual maturation was associated with cigarette smoking and alcohol drinking in late adolescence and whether this relation differed between boys and girls. Nine hundred and eighty boys and 1,149 girls, who participated in a cross-sectional study in middle school, were included in a follow-up study in high school 4 years later. Self-rating of pubertal status, as registered at baseline in middle school, was used to indicate the timing of sexual maturation. Age-adjusted odds ratios (ORs) with 95% confidence intervals (CIs), estimated by logistic regression, were used to assess the association between sexual maturation and alcohol drinking and daily smoking at follow-up. We found that girls who had matured early (OR 1.7, CI 1.2-2.4) or late (OR, 1.5, CI, 1.1-2.2) were both more likely to report more advanced drinking in late adolescence than were girls who were on time. Boys who had matured late were less likely (OR 0.5, CI 0.3-0.8) than boys who were on time to engage in advanced drinking. In general, daily smoking was more common among girls than boys, and more common among girls who had matured early (OR 1.5, CI 1.1-2.2) than among girls who were on time. Adjustment for social factors, e.g. parental education and marital status and parental drinking and smoking habits, did not substantially influence these results. We concluded that, for girls, but not for boys, early sexual maturation was associated with more advanced drinking and higher frequency of smoking in late adolescence. In boys, late sexual maturation was associated with reduced risk of advanced drinking.

Genetic and environmental influences on pubertal development: longitudinal data from Finnish twins at ages 11 and 14

To study sources of individual differences in pubertal development, the authors fit a sex-limitation common factor model to data reported, at ages 11 and 14 years, by 1,891 twin pairs on items that comprise the Pubertal Development Scale (PDS; A. C. Petersen, L. Crockett, M. Richards, & A. Boxer, 1988). The model divides variation into a general pubertal factor and item-specific variation and, in addition, decomposes it into constituent sources. In both boys and girls, genetic influences made the largest contribution to variance common to PDS items. Genetic and nonshared environmental factors accounted for variation specific to PDS items in boys, whereas for girls, common environmental influences were added for growth spurt and menarcheal status. For both common and item-specific variation, genetic effects were partially sex specific. Subsidiary analyses found accelerated maturation in both boys and girls who at age 14 were reared in father-absent homes.

Genetic and environmental effects on conduct disorder and alcohol dependence symptoms and their covariation at age 14

BACKGROUND

Alcohol misuse and conduct disorder (CD) are strongly associated in adolescents. Is their association due to shared genetic and environmental liabilities? We addressed that question with data obtained from structured interviews of 14-year-old Finnish twins.

METHODS

A total of 1854 twins completed face-to-face interviews. Univariate models, allowing for sex limitation, were fit to symptom counts for Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised diagnoses of CD and alcoholism to examine their genetic and environmental influences. Then, bivariate models evaluated the extent to which genetic and environmental influences contributed to the covariation between symptom counts for the two disorders.

RESULTS

A total of 822 twins (44% of the sample) reported one or more symptoms of CD; alcohol dependence symptoms were much less common, reported by only 12%. The correlation between the two symptom counts was 0.50. Models fit to the twin data demonstrated that CD symptoms were under significant genetic influence in both boys and girls, although those influences were predominantly sex specific. In contrast, alcohol dependence symptoms were, at this age, under sex-specific effects of common environments, with no evidence of genetic influences. Accordingly, the substantial covariation between alcohol dependence symptoms and those of CD was attributed entirely to shared environmental effects.

CONCLUSIONS

At age 14, genetic influences on alcohol dependence symptoms are negligible, and the correlated liabilities between these symptoms and those of CD are to be found in environmental factors that are common to both.

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.