Testing between-family associations in within-family comparisons

Middle-age dementia risk scores and old-age cognition: a quasi-experimental population-based twin study with over 20-year follow-up

BACKGROUND

Middle-age risk scores predict cognitive impairment, but it is not known if these associations are evident when controlling for shared genetic and environmental factors. Using two risk scores, self-report educational-occupational score and Cardiovascular Risk Factors, Aging and Dementia (CAIDE), we investigated if twins with higher middle-age dementia risk have poorer old-age cognition compared with their co-twins with lower risk.

METHODS

We used a population-based older Finnish Twin Cohort study with middle-age questionnaire data (n=15 169, mean age=52.0 years, SD=11.8) and old-age cognition measured via telephone interview (mean age=74.1, SD=4.1, n=4302). Between-family and within-family linear regression analyses were performed.

RESULTS

In between-family analyses (N=2359), higher educational-occupational score was related to better cognition (B=0.76, 95% CI 0.69 to 0.83) and higher CAIDE score was associated with poorer cognition (B=-0.73, 95% CI -0.82 to -0.65). Within twin-pair differences in educational-occupational score were significantly related to within twin-pair differences in cognition in dizygotic (DZ) pairs (B=0.78, 95% CI 0.25 to 1.31; N=338) but not in monozygotic (MZ) pairs (B=0.12, 95% CI -0.44 to 0.68; N=221). Within twin-pair differences in CAIDE score were not related to within twin-pair differences in cognition: DZ B=-0.38 (95% CI -0.90 to 0.14, N=343) and MZ B=-0.05 (95% CI -0.59 to 0.49; N=226).

CONCLUSION

Middle-age dementia risk scores predicted old-age cognition, but within twin-pair analyses gave little support for associations independent of shared environmental and genetic factors. Understanding genetic underpinnings of risk score-cognition associations is important for early detection of dementia and designing intervention trials.

Higher aggression is related to poorer academic performance in compulsory education

BACKGROUND

To conduct a comprehensive assessment of the association between aggression and academic performance in compulsory education.

METHOD

We studied aggression and academic performance in over 27,000 individuals from four European twin cohorts participating in the ACTION consortium (Aggression in Children: Unraveling gene-environment interplay to inform Treatment and InterventiON strategies). Individual level data on aggression at ages 7-16 were assessed by three instruments (Achenbach System of Empirically Based Assessment, Multidimensional Peer Nomination Inventory, Strengths and Difficulties Questionnaire) including parental, teacher and self-reports. Academic performance was measured with teacher-rated grade point averages (ages 12-14) or standardized test scores (ages 12-16). Random effect meta-analytical correlations with academic performance were estimated for parental ratings (in all four cohorts) and self-ratings (in three cohorts).

RESULTS

All between-family analyses indicated significant negative aggression-academic performance associations with correlations ranging from -.06 to -.33. Results were similar across different ages, instruments and raters and either with teacher-rated grade point averages or standardized test scores as measures of academic performance. Meta-analytical r's were -.20 and -.23 for parental and self-ratings, respectively. In within-family analyses of all twin pairs, the negative aggression-academic performance associations were statistically significant in 14 out of 17 analyses (r = -.17 for parental- and r = -.16 for self-ratings). Separate analyses in monozygotic (r = -.07 for parental and self-ratings), same-sex dizygotic (r's = -.16 and -.17 for parental and self-ratings) and opposite-sex dizygotic (r's = -.21 and -.19 for parental and self-ratings) twin pairs suggested partial confounding by genetic effects.

CONCLUSIONS

There is a robust negative association between aggression and academic performance in compulsory education. Part of these associations were explained by shared genetic effects, but some evidence of a negative association between aggression and academic performance remained even in within-family analyses of monozygotic twin pairs.

Why some siblings thrive whereas others struggle: A within-family study on recollections of childhood parental bonding and current adult depressive and anxiety symptoms

BACKGROUND

Brothers and sisters growing up together share a large proportion of their genes and rearing environment. However, some siblings thrive whereas others struggle. This study investigated family-wide childhood bonding experiences with mother and father, in addition to individual-specific recollections, in relation to current depressive and anxiety symptom levels in adulthood. We examined whether extraversion and internal locus of control (iLoC) had a protective effect in this.

METHODS

The sample consisted of 256 families with at least one lifetime depressed or anxious person (N = 596; ages 20-78). Multilevel modeling with cross-level interactions was used.

RESULTS

Adult siblings showed moderate to high agreement in their childhood parental bonding (PB) recollections. Over-and-above the association between individual-specific recollections of PB and adult internalizing symptoms, family-wide poor PB was additionally linked to elevated symptom levels. Within families characterized by poor maternal bonding persons with an iLoC were relatively less anxious (but not less depressed), whereas extraversion was not protective in this context.

LIMITATION

Although evidence exists that poor childhood PB has an impact on (adult) psychopathology, causality cannot be determined and possible recall bias of PB should be noted. Moreover, next to their moderating effects, extraversion and LoC may also act as mediators.

CONCLUSIONS

Our findings extend prior work by demonstrating the importance of siblings' childhood PB experiences next to a person's own recollections when investigating adult internalizing symptoms, while also elucidating individual differences within families.

Family Environment, Neurodevelopmental Risk, and the Environmental Influences on Child Health Outcomes (ECHO) Initiative: Looking Back and Moving Forward

The family environment, with all its complexity and diverse components, plays a critical role in shaping neurodevelopmental outcomes in children. Herein we review several domains of the family environment (family socioeconomic status, family composition and home environment, parenting behaviors and interaction styles, parental mental health and functioning, and parental substance use) and discuss how these domains influence neurodevelopment, with particular emphasis on mental health outcomes. We also highlight a new initiative launched by the National Institutes of Health, the Environmental influences on Child Health Outcomes (ECHO) program. We discuss the role that ECHO will play in advancing our understanding of the impact of the family environment on children's risk for psychiatric outcomes. Lastly, we conclude with important unanswered questions and controversies in this area of research, highlighting how ECHO will contribute to resolving these gaps in our understanding, clarifying relationships between the family environment and children's mental health.

Which adolescent factors predict alcohol misuse in young adulthood? A co-twin comparisons study

BACKGROUND AND AIMS

Research on adolescent predictors of later alcohol misuse is typically conducted on samples of singletons, and associations may be confounded by between-family differences. To address potential confounding, we applied a co-twin comparison design to evaluate whether differences between co-twins in a wide array of adolescent risk factors predicted differences in young adult alcohol misuse.

DESIGN

Longitudinal study in which associations between characteristics of the sample as adolescents were used to predict young adult alcohol misuse in individual-level analyses and co-twin comparisons.

SETTING

Finland.

PARTICIPANTS

A total of 3402 individuals (1435 complete twin pairs; 36% monozygotic; 57% female) from the FinnTwin12 study.

MEASUREMENTS

The young adult alcohol misuse outcome was a composite score of alcohol use and intoxication frequency. Adolescent predictors included factor scores representing academic performance, substance use, externalizing problems, internalizing problems, peer environment, physical health and relationship with parents; and single measures tapping alcohol expectancies, life events and pubertal development.

FINDINGS

In individual-level analyses, individuals with higher adolescent substance use, externalizing problems, time with friends, peer deviance, sports involvement, sleeping difficulties, parental discipline, positive alcohol expectancies and difficulty of life events reported higher alcohol misuse in young adulthood (Ps < 0.019, R²  = 0.0003-0.0310%). Conversely, those with higher adolescent internalizing problems, parent-child relationship quality and time with parents reported lower alcohol misuse (Ps < 0021, R²  = 0.0018-0.0093%). The associations with adolescent substance use and alcohol expectancies remained significant in co-twin comparisons (Ps < 0.049, R²  = 0.0019-0.0314%). Further, academic performance emerged as a significant predictor, such that individuals with higher grades compared with their co-twin reported higher young adult alcohol misuse (Ps < 0.029, R²  = 0.0449-0.0533%).

CONCLUSIONS

Adolescent substance use, positive alcohol expectancies and higher academic performance appear to be robust predictors of later alcohol misuse.

Assessing within- and between-family variations in an expanded measure of childhood adversity

Previous measures of childhood adversity have enabled the identification of powerful links with later-life wellbeing. The challenge for the next generation of childhood adversity assessment is to better characterize those links through comprehensive, fine-grained measurement strategies. The expanded, retrospective measure of childhood adversity presented here leveraged analytic and theoretical advances to examine multiple domains of childhood adversity at both the microlevel of siblings and the macrolevel of families. Despite the fact that childhood adversity most often occurs in the context of families, there is a dearth of studies that have validated childhood adversity measures on multiple members of the same families. Multilevel psychometric analyses of this childhood adversity measure administered to 1,194 siblings in 500 families indicated that the additional categories of childhood adversity were widely endorsed, and increased understanding of the sources and sequalae of childhood adversity when partitioned into within- and between-family levels. For example, multilevel confirmatory factor analyses (MCFAs) indicated that financial stress, unsafe neighborhood, and parental unemployment were often experienced similarly by siblings in the same families and stemmed primarily from family wide (between-family) sources. On the other hand, being bullied and school stressors were often experienced differently by siblings and derived primarily from individual (within-family) processes. Multilevel structural equation modeling (MSEM) further illuminated differential criterion validity correlations between these categories of childhood adversity with midlife psychological, social, and physical health. Expanded, multidomain, and multilevel measures of childhood adversity appear to hold promise for identifying layered causes and consequences of adverse childhood experiences. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Individual- and Family-Level Determinants of Risky Sexual Behavior Among Swedish- and Foreign-Born Young Adults 18-30 Years of Age, Residing in Skåne, Sweden

In Sweden, various public health interventions have been performed to reduce risky sexual behaviors among young people and promote safer and positive approaches to sexuality, while attempting to bridge the gap between the less privileged or more vulnerable young people and their more privileged peers. This study aimed to compare the individual- and familial-level determinants of risky sexual behavior among foreign-born and Swedish-born young adults 18-30 years of age residing in Skåne, the south of Sweden. This was a cross-sectional study that used a questionnaire to collect data from 2968 randomly selected respondents between 18 and 30 years between January and March 2013. The associations were analyzed using chi-square tests, and simple and multiple logistic regression analyses. Younger age, i.e., individual-level factor, and living with only one parent or another person while growing up, i.e., familial-level factor, increased the risk of engaging in sexual risk taking for both Swedish- and foreign-born youth. Male gender was related to a higher risk of engaging in sexual risk-taking behaviors among foreign-born youth but was not as important as influence on sexual risk taking among Swedish-born youth. Parental education level, on the other hand, was significantly associated with sexual intercourse on the "first night" and early sexual debut solely among Swedish-born youth. Condom use was not associated with any family-level factor among both Swedish-born and foreign-born youth. The design of sexual reproductive health and rights messages and interventions to target risky sexual behavior among Swedish youth should take into consideration immigration status (for example, being Swedish-born or foreign-born), individual- and family-level characteristics, as well as the type of behavioral change or outcome desired.

Within-Family Differences in Mothers' Support to Adult Children in Black and White Families

Data collected from a representative sample of 157 Black and 394 White older women is used to explore within-family differences in mother-to-child support. High rates of differentiation in both Black and White families were found. Within-family analyses revealed more similarities than differences in the effects of adult children's characteristics on mothers' likelihood of providing support. For both groups, mothers were most likely to provide support to children who had fewer resources, greater need, and who had provided the mothers with support. Children's health problems were better predictors of support among Black than White mothers, whereas children's gender played a larger role in White than Black mothers' provision of support; however, both groups of mothers favored daughters and children with poor health. In sum, these patterns provide little support for the argument that family solidarity is substantially more important in explaining intergenerational exchanges in Black than White families.

All in the Family? A Twin-Based Analysis of Associations Between Occupational Risk Factors, Drinking, and Tobacco Use in Employed Men

BACKGROUND

Employment-related substance use can negatively affect both workplace and worker. Relationships between workplace characteristics and substance use may be explained by genetic and environmental effects; this research uses a co-twin control (discordant twin) design to disentangle these influences.

METHODS

This study compared population-level to discordant twin pair relationships to analyze the genetic and environmental influences of work-related risks on substance use in N = 2,138 dizygotic and monozygotic male twins from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders. Negative binomial and logistic regressions were fit to predict differences in the frequency of drinking, typical and maximum number of drinks, the number of cigarettes per day, and any binge drinking or any tobacco use across occupation, work hours, job strain, problems with coworkers, and perceived job insecurity.

RESULTS

In population-level analyses, several work-related variables were associated with substance use. The population-level associations of occupation with typical and maximum drinks per day and of problems with coworkers to binge drinking were not significant at the twin level. At both the population and discordant twin levels, only higher occupational status was associated with a lower likelihood of regular tobacco use (odds ratio 0.44, 95% confidence interval 0.21, 0.94).

CONCLUSIONS

Variation in genes and shared environment appears to account for many of the population-level relationships between work-related stressors and substance use. Work stressors may not be the most fruitful intervention point when aiming to reduce alcohol or tobacco use, although men in certain high-stress occupations may be at greater risk for substance use.

Separating Family-Level and Direct Exposure Effects of Smoking During Pregnancy on Offspring Externalizing Symptoms: Bridging the Behavior Genetic and Behavior Teratologic Divide

Maternal smoking during pregnancy (MSDP) has been robustly associated with externalizing problems and their developmental precursors in offspring in studies using behavioral teratologic designs (Wakschlag et al., Am J Public Health 92(6):966-974, 2002; Espy et al., Dev Psychol 47(1):153-169, 2011). In contrast, the use of behavior genetic approaches has shown that the effects commonly attributed to MSDP can be explained by family-level variables (D'Onofrio et al., Dev Psychopathol 20(01):139-164, 2008). Reconciling these conflicting findings requires integration of these study designs. We utilize longitudinal data on a preschool proband and his/her sibling from the Midwest Infant Development Study-Preschool (MIDS-P) to test for teratologic and family level effects of MSDP. We find considerable variation in prenatal smoking patterns both within and across pregnancies within families, indicating that binary smoking measures are not sufficiently capturing exposure. Structural equation models indicate that both conduct disorder and oppositional defiant disorder symptoms showed unique effects of MSDP over and above family level effects. Blending high quality exposure measurement with a within-family design suggests that it is premature to foreclose the possibility of a teratologic effect of MSDP on externalizing problems. Implications and recommendations for future studies are discussed.

Gender differences in the developmental risk of onset of alcohol, nicotine, and marijuana use and the effects of nicotine and marijuana use on alcohol outcomes

OBJECTIVE

This study aimed to (a) characterize gender-specific risk of onset of alcohol, nicotine, and marijuana use developmentally; (b) investigate the effects of early-onset status and frequency of nicotine and marijuana use on alcohol outcomes, controlling for the effects of alcohol use; and (c) examine gender differences in the developmental trajectories of alcohol outcomes and the effects of nicotine and marijuana use on alcohol outcomes.

METHOD

This study conducted secondary analysis on a longitudinal study that recruited at-risk youth through fathers' drunk-driving records and door-to-door canvassing in the midwestern United States. The sample included 160 female-male sibling pairs who were assessed on substance use and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnosis from early childhood to young adulthood.

RESULTS

Although males were at higher risk for being early-onset alcohol users, females tended to be at higher risk for initiating marijuana use at younger ages. When early onset and amount of alcohol use were controlled for, early onset of nicotine and marijuana use did not contribute to alcohol outcomes, but frequencies of nicotine and marijuana use did. We also found the associations of quantity/frequency of alcohol and marijuana use with drinking problems to be stronger among females than among males.

CONCLUSIONS

Higher frequencies of nicotine and marijuana use may contribute to worse alcohol outcomes above and beyond the effect of alcohol use. Females tend to be at higher risk than males for initiating marijuana use and meeting an alcohol use disorder diagnosis at younger ages as well as being more vulnerable to a negative impact of alcohol and marijuana use.

Future directions in research on sexual minority adolescent mental, behavioral, and sexual health

This article describes current knowledge on sexual, mental, and behavioral health of sexual minority (SM) youth and identifies gaps that would benefit from future research. A translational sciences framework is used to conceptualize the article, discussing findings and gaps along the spectrum from basic research on prevalence and mechanisms, to intervention development and testing, to implementation. Relative to adults, there has been much less research on adolescents and very few studies that had longitudinal follow-up beyond 1 year. Due to historical changes in the social acceptance of the SM community, new cohorts are needed to represent contemporary life experiences and associated health consequences. Important theoretical developments have occurred in conceptualizing mechanisms that drive SM health disparities and mechanistic research is underway, including studies that identify individual and structural risk/protective factors. Research opportunities exist in the utilization of sibling-comparison designs, inclusion of parents, and studying romantic relationships. Methodological innovation is needed in sampling SM populations. There has been less intervention research and approaches should consider natural resiliencies, life-course frameworks, prevention science, multiple levels of influence, and the importance of implementation. Regulatory obstacles are created when ethics boards elect to require parental permission and ethics research is needed. There has been inconsistent inclusion of SM populations in the definition of "health disparity population," which impacts funding and training opportunities. There are incredible opportunities for scholars to make substantial and foundational contributions to help address the health of SM youth, and new funding opportunities to do so.

Adolescent alcohol abuse and adverse adult outcomes: evaluating confounds with drinking-discordant twins

BACKGROUND

Adolescent alcohol abuse is associated with adverse outcomes in early adulthood, but differences in familial status and structure and household and community environments correlate with both adolescent drinking and adverse adult outcomes and may explain their association. We studied drinking-discordant twin pairs to evaluate such confounds to ask: Will between-family associations replicate in within-family comparisons?

METHODS

With longitudinal data from >3,000 Finnish twins, we associated drinking problems at age 18½ with 13 outcomes assessed at age 25; included were sustained substance abuse, poor health, physical symptoms, early coital debut, multiple sexual partners, life dissatisfaction, truncated education, and financial problems. We assessed associations among twins as individuals with linear regression adjusted for correlated observations; within-family analyses of discordant twin pairs followed, comparing paired means for adult outcomes among co-twins discordant for adolescent problem drinking. Defining discordance by extreme scores on self-reported problem drinking at age 18½ permitted parallel analyses of twins as individuals and discordant twin pairs. Alternate definitions of pair-wise discordance and difference score correlations across the entire twin sample yielded supplementary analyses.

RESULTS

All individual associations were highly significant for all definitions of discordance we employed. Depending on definitions of discordance, 11 to 13 comparisons of all drinking-discordant twin pairs and 3 to 6 comparisons of discordant monozygotic (MZ) twin pairs replicated between-family associations. For most outcomes, effect size attenuated from individual-level analysis to that within discordant MZ twin pairs providing evidence of partial confounding in associations reported in earlier research. The exception was the General Health Questionnaire (GHQ); at age 25, GHQ-12 had equivalent associations with age 18½ Rutgers Alcohol Problem Index across all comparisons.

CONCLUSIONS

Our analyses control for shared family background, and, partly or fully, for shared genes, to yield within-family replications and more compelling evidence than previously available that adolescent alcohol abuse disrupts transitions into early adulthood.

Behind the wheel and on the map: Genetic and environmental associations between drunk driving and other externalizing behaviors

Drunk driving, a major contributor to alcohol-related mortality, has been linked to a variety of other alcohol-related (e.g., Alcohol Dependence, early age at first drink) and non-alcohol-related externalizing behaviors. In a sample of 517 same-sex twin pairs from the National Longitudinal Study of Adolescent Health, we examined 3 conceptualizations of the etiology of drunk driving in relation to other externalizing behaviors. A series of behavioral-genetic models found consistent evidence for drunk driving as a manifestation of genetic vulnerabilities toward a spectrum of alcohol-related and non-alcohol-related externalizing behaviors. Most notably, multidimensional scaling analyses produced a genetic "map" with drunk driving located near its center, supporting the strength of drunk driving's genetic relations with a broad range of externalizing behaviors. In contrast, nonshared environmental associations with drunk driving were weaker and more diffuse. Drunk driving may be a manifestation of genetic vulnerabilities toward a broad externalizing spectrum.

Associations between sexual abstinence ideals, religiosity, and alcohol abstinence: a longitudinal study of Finnish twins

We analyzed prevalence and stability of attitudes endorsing sexual abstinence ideals from late adolescence into early adulthood and studied associations of these attitudes with religiosity and alcohol abstinence in a sexually liberal Nordic society. Our population-based sample of Finnish twins permitted comparisons of co-twins concordant for religiosity but discordant for drinking to evaluate the association of sexual abstinence ideals with alcohol abstinence, controlling for household environment. From age 17 to 24, endorsement of sexual abstinence as a romantic ideal declined from 25% to 15%. Religiosity and alcohol abstinence correlated, both separately and together, with endorsing sexual abstinence. Abstinence ideals were associated with literal belief in fundamental tenets of the Bible. The association of sexual abstinence ideals with alcohol abstinence was confirmed in within-family comparisons of co-twins discordant for drinking but concordant for religiosity. Alcohol-abstinent twins were significantly more likely than their non-alcohol-abstinent twin siblings to endorse sexual abstinence ideals; that result suggests the association of sexual abstinence ideals with abstaining from alcohol is not explained by unmeasured confounds in familial background and structure. Our longitudinal results and analyses of discordant twins suggest that attitudes toward sexual abstinence ideals are embedded within other conservative attitudes and behaviors.

Testing putative causal associations of risk factors for early intercourse in the study of twin adults: genes and environment (STAGE)

Adverse childhood experiences and substance use have been identified as potential causal risk factors for early-onset sexual intercourse. While it is possible that exposure to these risk factors directly increases the likelihood of engaging in early intercourse, an alternative explanation is that observed associations between these variables are due to shared familial confounds. These unmeasured confounds may increase the likelihood of being exposed to these risk factors and of engaging in early intercourse. Participants drawn from a population-based study of Swedish adult twins (ages 19-47 years; N = 12,126) reported on their history of exposure to early physical and sexual trauma, cigarette use, and cannabis use. We investigated the nature of the association between these risk factors and young age at first intercourse, using a comparison of twins differentially exposed to each risk factor. When compared to non-exposed, unrelated individuals, participants who reported adverse childhood experiences or who engaged in early cigarette use or cannabis use were more likely to engage in early intercourse. However, co-twin comparisons indicated that observed associations between these risk factors and early intercourse may be due to familial factors shared within twin pairs, and risk factor exposure may not lead directly to early intercourse. Our results suggest that preventing trauma exposure or preventing or delaying adolescents' cigarette smoking or cannabis use may not effectively delay intercourse onset; instead, other aspects of the adolescent's environment should be addressed.

Using a sibling design to compare childhood adversities in female patients with BPD and their sisters

Abuse and neglect are well-established risk correlates of borderline personality disorder (BPD). The goal of this study was to examine whether BPD probands can be differentiated from their sisters with respect to a range of developmental adversity and maltreatment indicators, including retrospective self-reports of past experiences of childhood abuse and neglect, dysfunctional parent-child relationships and peer victimization and dysfunctional peer relationships. A total of 53 patients with BPD were compared to 53 sisters who were currently free of psychopathology on measures assessing childhood adversities. Both probands and sisters reported similar prevalence of intrafamilial abuse, although BPD patients reported more severe physical and emotional abuse. BPD patients reported higher prevalence of physical abuse by peers. These findings generally support the principle of multifinality, in which similar histories of adversities can be associated with a variety of outcomes, ranging from psychopathology to resilience.

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.

True Love Waits? A Sibling-Comparison Study of Age at First Sexual Intercourse and Romantic Relationships in Young Adulthood

This study tested whether the timing of first sexual intercourse in adolescence predicts romantic outcomes in adulthood, including union formation, number of romantic partners, and relationship dissatisfaction. Participants were 1,659 same-sex sibling pairs from the National Longitudinal Study of Adolescent Health, who were followed from adolescence (mean age = 16 years) to young adulthood (mean age = 29 years). The timing of participants’ first sexual intercourse was classified as early (at age 14 or earlier), on time (between the ages of 15 and 19), or late (at age 19 or older). Compared with early and on-time age at first sex, late age at first sex was associated with decreased odds of marriage or nonmarital cohabitation and fewer romantic partners in adulthood. Among individuals who had married or cohabited with a partner, late timing of first sex was associated with significantly reduced levels of relationship dissatisfaction, even after controlling for genetic and environmental differences between families (using a sibling-comparison model), demographic outcomes in adulthood, and involvement in dating during adolescence. These results underscore the contribution of a life-span approach to our understanding of romantic relationships.

Why does early sexual intercourse predict subsequent maladjustment? Exploring potential familial confounds

OBJECTIVE

Previous studies have found an association between early age at first sexual intercourse and subsequent psychosocial maladjustment. Using a quasi-experimental approach, we examined the extent to which this observed association may be due to familial confounds not explored in prior research.

METHODS

Using a population-based cohort of Swedish adult twins (ages 19-47; N = 12,126), we examined the nature of the association between early sexual intercourse (i.e., first intercourse occurring before age 16) and various outcomes reflecting psychosocial health, including substance use, depression, criminal convictions, and adolescent childbearing. We used two methods--discordant-twin analyses and bivariate twin modeling--to estimate the extent to which genetic and environmental confounds explained observed associations.

RESULTS

Individuals who engaged in early intercourse were at greater risk for most of the adverse psychosocial health outcomes measured in this study. However, twin pairs discordant for engaging in early intercourse did not differ significantly in their risk for psychosocial maladjustment. Our results indicated that early age at first sexual intercourse and subsequent psychosocial maladjustment may be associated because of familial factors shared by twins.

CONCLUSIONS

Early intercourse may be associated with poor psychosocial health largely due to shared familial influences rather than through a direct causal connection. Therefore, effective and efficient interventions should address other risk factors common to early intercourse and poor psychosocial health.

Environmental and genetic pathways between early pubertal timing and dieting in adolescence: distinguishing between objective and subjective timing

BACKGROUND

Early pubertal timing in girls is associated with elevated risk for dieting and eating pathology. The relative importance of biological versus socio-environmental mechanisms in explaining this association remains unclear. Moreover, these mechanisms may differ between objective measures of pubertal development and girls' subjective perceptions of their own maturation.

METHOD

The sample comprised 924 sister pairs from the National Longitudinal Study of Adolescent Health. Objective pubertal timing (menarcheal age), girls' perceptions of pubertal status and timing relative to peers, dieting and disordered eating behaviors were assessed during a series of confidential in-home interviews.

RESULTS

Behavioral genetic models indicated that common genetic influences accounted for the association between early menarcheal age and increased risk for dieting in adolescence. In contrast, girls' subjective perceptions of their timing relative to peers were associated with dieting through an environmental pathway. Overall, subjective and objective measures of pubertal timing accounted for 12% of the variance in dieting.

CONCLUSIONS

Genetic differences in menarcheal age increase risk for dieting among adolescent girls, while girls' perceptions of their maturation represent an environmentally mediated risk.

Rutgers alcohol problem index scores at age 18 predict alcohol dependence diagnoses 7 years later

BACKGROUND

The Rutgers Alcohol Problem Index (RAPI) is widely used to assess adolescent drinking-related problems. We asked how well RAPI, administered in late adolescence, predicts alcohol diagnoses at age 25 in a 7-year follow-up.

METHODS

At age 18, a population-based sample of Finnish twins completed RAPI by postal questionnaire; 597 (300 male) twins, from pairs discordant and concordant for age 18 RAPI scores, were interviewed at age 25 with the SSAGA, yielding DSM-IIIR diagnoses. Polychoric correlations between RAPI and alcohol diagnoses and symptoms, the area under the response operator characteristic (ROC) curve, and the odds ratio of outcome diagnosis per unit change in adolescent RAPI were analyzed. Twin pairs discordant for both adolescent RAPI and adult diagnoses permitted within-family replications for the full sample and separately by sex.

RESULTS

Nearly half the interviewed twins met diagnostic criteria for alcohol dependency (46.2%) or abuse (1.5%). Age 18 RAPI scores significantly correlated with diagnoses (0.52) and symptom counts (0.55). ROC analysis found a 74% probability that adolescent RAPI scores will be higher among those with an alcohol diagnosis at age 25 than for those without. The odds ratio of outcome alcohol diagnosis per unit increase in adolescent 18 RAPI exceeded 10.0. Within-family comparisons of 117 twin pairs discordant for both age 18 RAPI and age 25 alcohol diagnoses replicated the between-family associations. In both between-family and within-family analyses, RAPI was more predictive of alcohol diagnoses among females.

CONCLUSIONS

Our results offer evidence, including that from informative comparisons of co-twins discordant for both predictor and outcome, that RAPI scores in late adolescence robustly predict alcohol diagnoses in early adulthood. Accordingly, our results also provide new evidence that one pathway to problem drinking in early adulthood is a direct one from problem drinking in adolescence.

A longitudinal twin study of effects of adolescent alcohol abuse on the neurophysiology of attention and orienting

BACKGROUND

Long-term functional brain effects of adolescent alcohol abuse remain uncertain, partially because of difficulties in distinguishing inherited deficits from neuronal effects of ethanol and by confounds associated with alcohol abuse, especially nicotine exposure. We conducted a longitudinal twin study to determine neurocognitive effects of adolescent alcohol abuse, as measured with the auditory event-related potential (ERP) component P3, a putative marker of genetic vulnerability to alcoholism.

METHODS

Twin pairs (N=177; 150 selected for intrapair concordance/discordance for alcohol-related problems at age 18½) were recruited from ongoing studies of twins born 1975-1979 in Finland. Alcohol and tobacco use were assessed with questionnaires at ages 16, 17, 18½, and ~25, and by a structured psychiatric interview concurrent with the ERP testing at mean age 25.8. During ERP recordings, subjects were instructed to detect target tones within a train of frequent "standards" and to ignore occasional "novel" sounds. To distinguish familial factors from ethanol effects, ERP and self-reported alcohol use measures were incorporated into hierarchical multiple regression (HMR) analysis, and intrapair differences in ERP were associated with intra-pair differences in alcohol variables.

RESULTS

Novel-sound P3 amplitude correlated negatively with self-reported alcohol use in both between- and within-family analyses. No similar effect was observed for target-tone P3. HMR results suggest that twins' similarity for novel-sound P3 amplitude is modulated by their alcohol use, and this effect of alcohol use is influenced by genetic factors.

CONCLUSIONS

Our results, from a large sample of twins selected from a population-based registry for pairwise concordance/discordance for alcohol problems at 18½, demonstrate that adolescent alcohol abuse is associated with subtle neurophysiological changes in attention and orienting. The changes are reflected in decreased novel-sound P3 amplitude and may be modified by genetic factors.

Does religious involvement protect against early drinking? A behavior genetic approach

BACKGROUND

Adolescent involvement in religious organizations has been hypothesized to protect against early age at first drink. However, the correlation between adolescent religiosity and later age at first drink may be confounded by environmental or genetic differences between families. This study tests whether, after controlling for shared environmental and genetic confounds using a behavior genetic design, the association between individual levels of religiosity and earlier age at first drink is still evident.

METHOD

Twin and sibling pairs were drawn from the National Longitudinal Study of Adolescent Health, a nationally-representative sample of US adolescents. Age at first drink was measured as how old adolescents were when they first had a drink of beer, wine, or liquor. Religiosity was measured using four items concerning frequency of religious activities and importance of religious beliefs. Using twins and siblings who were discordant for religiosity, analyses tested whether religious adolescents had a later age at first drink than their non-religious co-twins/co-siblings.

RESULTS

Religious adolescents did not differ from their non-religious siblings in their mean age at first drink. Results from survival models indicate that environmental differences between families completely account for the correlation between religiosity and later age at first drink.

CONCLUSIONS

Results suggest that individual religious involvement is a proxy variable for family or cultural environments that are salient for when adolescents initiate alcohol use. Future research is needed to identify specific protective environments in religious families. These results have implications for both public policy and etiological theory.

Associations between father absence and age of first sexual intercourse

Children raised without a biological father in the household have earlier average ages of first sexual intercourse than children raised in father-present households. Competing theoretical perspectives have attributed this either to effects of father absence on socialization and physical maturation or to nonrandom selection of children predisposed for early sexual intercourse into father-absent households. Genetically informative analyses of the children of sister dyads (N = 1,382, aged 14-21 years) support the selection hypothesis: This association seems attributable to confounded risks, most likely genetic in origin, which correlated both with likelihood of father absence and early sexual behavior. This holds implications for environmental theories of maturation and suggests that previous research may have inadvertently overestimated the role of family structure in reproductive maturation.

Prospective associations of early-onset Axis I disorders with developing eating disorders

OBJECTIVE

The purpose of this study is to analyze the developmental relationships of adolescent-onset Axis I mental disorders and eating disorders (EDs).

METHOD

One thousand three hundred eighteen adolescent twins born from 1983 to 1987 completed a professionally administered semistructured psychiatric interview at the age of 14 years and a questionnaire follow-up at the age of 17.5 years.

RESULTS

Eating disorders at the age of 17.5 years were significantly predicted by major depressive disorder (odds ratio, 5.9; 95% confidence interval, 2.6-15.3) and generalized anxiety disorder (GAD) (odds ratio, 4.7; 95% confidence interval, 1.8-15.6) at the age of 14 years, when baseline EDs were excluded. Early-onset major depressive disorder in combination with GAD increased the likelihood of developing EDs compared with either mood or anxiety disorders alone. Similar risks and trends were evident in within-family analyses of twin pairs discordant for baseline predictors and ED outcome.

CONCLUSIONS

Depressive disorder and GAD that manifest at that age of 14 years predict future EDs. Analysis of discordant twins suggested that early-onset depressive disorder and GAD prospectively relate to EDs in adolescence, even after familial factors are taken into account.

Associations of individual and family eating patterns during childhood and early adolescence: a multicentre European study of associated eating disorder factors

The objective of this study was to examine whether there is an association between individual and family eating patterns during childhood and early adolescence and the likelihood of developing a subsequent eating disorder (ED). A total of 1664 participants took part in the study. The ED cases (n 879) were referred for assessment and treatment to specialized ED units in five different European countries and were compared to a control group of healthy individuals (n 785). Participants completed the Early Eating Environmental Subscale of the Cross-Cultural (Environmental) Questionnaire, a retrospective measure, which has been developed as part of a European multicentre trial in order to detect dimensions associated with ED in different countries. In the control group, also the General Health Questionnaire-28 (GHQ-28), the semi-structured clinical interview (SCID-I) and the Eating Attitudes Test (EAT-26) were used. Five individually Categorical Principal Components Analysis (CatPCA) procedures were adjusted, one for each theoretically expected factor. Logistic regression analyses indicated that the domains with the strongest effects from the CatPCA scores in the total sample were: food used as individualization, and control and rules about food. On the other hand, healthy eating was negatively related to a subsequent ED. When differences between countries were assessed, results indicated that the pattern of associated ED factors did vary between countries. There was very little difference in early eating behaviour on the subtypes of ED. These findings suggest that the fragmentation of meals within the family and an excessive importance given to food by the individual and the family are linked to the later development of an ED.

Rethinking Timing of First Sex and Delinquency

The relation between timing of first sex and later delinquency was examined using a genetically informed sample of 534 same-sex twin pairs from the National Longitudinal Study of Adolescent Health, who were assessed at three time points over a 7-year interval. Genetic and environmental differences between families were found to account for the association between earlier age at first sex and increases in delinquency. After controlling for these genetic and environmental confounds using a quasi-experimental design, earlier age at first sex predicted lower levels of delinquency in early adulthood. The current study is contrasted with previous research with non-genetically informative samples, including Armour and Haynie. Results suggest a more nuanced perspective on the meaning and consequences of adolescent sexuality than is commonly put forth in the literature.

Gene-environment correlation and interaction in peer effects on adolescent alcohol and tobacco use

Peer relationships are commonly thought to be critical for adolescent socialization, including the development of negative health behaviors such as alcohol and tobacco use. The interplay between genetic liability and peer influences on the development of adolescent alcohol and tobacco use was examined using a nationally-representative sample of adolescent sibling pairs and their best friends. Genetic factors, some of them related to an adolescent's own substance use and some of them independent of use, were associated with increased exposure to best friends with heavy substance use--a gene-environment correlation. Moreover, adolescents who were genetically liable to substance use were more vulnerable to the adverse influences of their best friends--a gene-environment interaction.

A behavior genetic investigation of adolescent motherhood and offspring mental health problems

The present study examines the relations between adolescent motherhood and children's behavior, substance use, and internalizing problems in a sample of 1,368 children of 712 female twins from Australia. Adolescent motherhood remained significantly associated with all mental health problems, even when using a quasiexperimental design capable of controlling for genetic and environmental confounds. However, the relation between adolescent motherhood and offspring behavior problems and substance use was partially confounded by family background variables that influence both generations. The results are consistent with a causal relation between adolescent motherhood and offspring mental health problems, and they highlight the usefulness of behavior genetic designs when examining putative environmental risks for the development of psychopathology. The generalizability of these results to the United States, which has a higher adolescent birth rate, is discussed.

Marital conflict and conduct problems in Children of Twins

The Children-of-Twins design was used to test whether associations between marital conflict frequency and conduct problems can be replicated within the children of discordant twin pairs. A sample of 2,051 children (age 14-39 years) of 1,045 twins was used to estimate the genetic and environmental influences on marital conflict and determine whether genetic or environmental selection processes underlie the observed association between marital conflict and conduct problems. Results indicate that genetic and nonshared environmental factors influence the risk of marital conflict. Furthermore, genetic influences mediated the association between marital conflict frequency and conduct problems. These results highlight the need for quasiexperimental designs in investigations of intergenerational associations.

Sensation seeking and alcohol use: a meta-analytic review

A meta-analysis was conducted to investigate the association between sensation seeking and alcohol use. Analysis of 61 studies revealed a small to moderate size, heterogeneous effect (mean weighted r=.263) between alcohol use and sensation seeking total scale scores. Analysis of the four sensation seeking components indicated that disinhibition was most strongly correlated with alcohol use (mean weighted r=.368). Categorical moderator analyses revealed that studies that did, versus did not, analyze covariates yielded smaller effect sizes. Continuous moderator analyses indicated that earlier published studies and higher percentages of male and white Caucasian participants were associated with stronger effect sizes between sensation seeking and alcohol use. Novel statistical methodologies for analyzing the association between sensation seeking and alcohol use were proposed and recommendations for future research were suggested.

A genetically informed study of marital instability and its association with offspring psychopathology

Parental divorce is associated with a number of emotional and behavioral problems in young-adult offspring, but theoretical and empirical considerations suggest that the relation may be partially or fully accounted for by passive gene-environment correlation or environmental selection characteristics. The current study used the Children of Twins Design to explore whether shared environmental or genetic factors confound the relationship between parental marital instability and measures of psychopathology. Comparisons of the offspring of adult twins in Australia on 3 factors of abnormal behavior, including drug and alcohol, behavioral, and internalizing problems, suggest that environmental influences associated with divorce account for the higher rates of psychopathology. The results are consistent with a causal connection between marital instability and psychopathology in young-adult offspring.

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.

Development and modification of child food preferences and eating patterns: behavior genetics strategies

Behavioral genetics (BG) designs can offer useful strategies for studying the development of child food preferences and eating patterns. This review summarizes BG designs that tested familial influences on child eating behavior and implicated both genetic and home environmental factors. A range of BG strategies, including family and pseudo-family designs, classic twins designs, discordant sibling designs, cotwin control designs, and high-risk designs, have provided information on child development that could not have been obtained from the analysis of singletons. BG designs can provide can powerful tools for testing environmental theories of child nutrition and, potentially, for better understanding between-child variability in response to dietary interventions for overweight. The term BG may misleadingly imply only the classic twin design or just heritability estimation; BG strategies can be adapted creatively to address a range of questions concerning the development of child appetite and eating regulation.

Prenatal programming of behavior: a twin-study perspective

This paper reviews three designs that compare co-twins in tests of prenatal programming. The first design uses co-twin comparisons to attempt within-family replications of between-family associations, reported in non-twins, between reduced fetal growth and risk for later disease or behavior disorder. These replication efforts are mixed, perhaps due to small samples of weight-discordant twins, perhaps confounded by differences in the meaning of fetal growth in twins. The second design compares monozygotic co-twins from pairs differing in their placentation, with some evidence, again constrained by sample limitations that twins sharing a single placenta are more alike in dimensions of cognitive ability and personality. A third design employs a dermatoglyphic index of bilateral asymmetry as a marker of reduced buffering from environmental noise, with positive results from MZ twins that await necessary replication in longitudinal data from non-twins. Twin comparisons, especially the comparisons of monozygotic co-twins, offer an informative and incisive approach for research on prenatal programming in humans.