Search

Background: Both genetic and environmental influences have been shown to contribute to the association between physical activity and overall academic performance. The authors examined whether leisure-time physical activity (LTPA) shares genetic and environmental variances between spelling, essay writing, reading aloud, reading comprehension, and mathematics in early adolescence. Moreover, they investigated whether genetic polymorphisms associated with physical activity behavior affect these academic skills. Methods: Participants were 12-year-old Finnish twins (n = 4356–4370 twins/academic skill, 49% girls). Academic skills were assessed by teachers, and LTPA was self-reported. Polygenic scores for physical activity behavior were constructed from the UK Biobank. Quantitative genetic modeling and linear regression models were used to analyze the data. Results: The trait correlations between LTPA and academic skills were significant but weak (r =.05–.08). The highest trait correlation was found between LTPA and mathematics. A significant genetic correlation was revealed between LTPA and essay writing (rA =.14). Regarding polygenic scores of physical activity, the highest correlations were found with reading comprehension, spelling, and essay writing, but these results only approached statistical significance (P values =.09–.15). Conclusions: The authors' results suggest that reading and writing are the academic skills that most likely share a common genetic background with LTPA. [ABSTRACT FROM AUTHOR]

Background: We sought to clarify the impact of adolescent alcohol misuse on adult physical health and subjective well‐being. To do so, we investigated both the direct associations between adolescent alcohol misuse and early midlife physical health and life satisfaction and the indirect effects on these outcomes attributable to subsequent alcohol problems. Method: The sample included 2733 twin pairs (32% monozygotic; 52% female) from the FinnTwin16 study. Adolescent alcohol misuse was a composite of frequency of drunkenness, frequency of alcohol use, and alcohol problems at ages 16, 17, and 18.5. The early midlife outcomes included somatic symptoms, self‐rated health, and life satisfaction at age 34. The mediators examined as part of the indirect effect analyses included alcohol problems from the Rutgers Alcohol Problem Index at ages 24 and 34. Serial mediation and co‐twin comparison models were applied and included covariates from adolescence and early midlife. Results: There were weak direct associations between adolescent alcohol misuse and early midlife physical health and life satisfaction. However, there was stronger evidence for indirect effects, whereby young adult and early midlife alcohol problems serially mediated the relationship between adolescent alcohol misuse and early midlife somatic symptoms (β = 0.03, 95% CI [0.03, 0.04]), self‐rated health (β = −0.02, 95% CI [−0.03, −0.01]), and life satisfaction (β = −0.03, CI [−0.04, −0.02]). These serial mediation effects were robust in co‐twin comparison analyses. Conclusions: These results provide evidence that alcohol problems are a primary driver linking adolescent alcohol misuse and poor health outcomes across the lifespan. [ABSTRACT FROM AUTHOR]

Co-twin comparisons address familial confounding by controlling for genetic and environmental influences that twin siblings share. We applied the co-twin comparison design to investigate associations of adolescent factors with alcohol dependence (AD) symptoms. Participants were 1286 individuals (581 complete twin pairs; 42% monozygotic; and 54% female) from the FinnTwin12 study. Predictors included adolescent academic achievement, substance use, externalizing problems, internalizing problems, executive functioning, peer environment, physical health, relationship with parents, alcohol expectancies, life events, and pubertal development. The outcome was lifetime AD clinical criterion count, as measured in young adulthood. We examined associations of each adolescent domain with AD symptoms in individual-level and co-twin comparison analyses. In individual-level analyses, adolescents with higher levels of substance use, teacher-reported externalizing problems at age 12, externalizing problems at age 14, self- and co-twin-reported internalizing problems, peer deviance, and perceived difficulty of life events reported more symptoms of AD in young adulthood (ps < .044). Conversely, individuals with higher academic achievement, social adjustment, self-rated health, and parent-child relationship quality met fewer AD clinical criteria (ps < .024). Associations between adolescent substance use, teacher-reported externalizing problems, co-twin-reported internalizing problems, peer deviance, self-rated health, and AD symptoms were of a similar magnitude in co-twin comparisons. We replicated many well-known adolescent correlates of later alcohol problems, including academic achievement, substance use, externalizing and internalizing problems, self-rated health, and features of the peer environment and parent-child relationship. Furthermore, we demonstrate the utility of co-twin comparisons for understanding pathways to AD. Effect sizes corresponding to the associations between adolescent substance use, teacher-reported externalizing problems, co-twin-reported internalizing problems, peer deviance, and self-rated health were not significantly attenuated (p value threshold = .05) after controlling for genetic and environmental influences that twin siblings share, highlighting these factors as candidates for further research. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Maternal smoking during pregnancy (MSDP) has been linked to offspring's externalizing problems. It has been argued that socio-demographic factors (e.g. maternal age and education), co-occurring environmental risk factors, or pleiotropic genetic effects may account for the association between MSDP and later outcomes. This study provides a comprehensive investigation of the association between MSDP and a single harmonized component of externalizing: aggressive behaviour, measured throughout childhood and adolescence. Methods: Data came from four prospective twin cohorts – Twins Early Development Study, Netherlands Twin Register, Childhood and Adolescent Twin Study of Sweden, and FinnTwin12 study – who collaborate in the EU-ACTION consortium. Data from 30 708 unrelated individuals were analysed. Based on item level data, a harmonized measure of aggression was created at ages 9–10; 12; 14–15 and 16–18. Results: MSDP predicted aggression in childhood and adolescence. A meta-analysis across the four samples found the independent effect of MSDP to be 0.4% (r = 0.066), this remained consistent when analyses were performed separately by sex. All other perinatal factors combined explained 1.1% of the variance in aggression across all ages and samples (r = 0.112). Paternal smoking and aggressive parenting strategies did not account for the MSDP-aggression association, consistent with the hypothesis of a small direct link between MSDP and aggression. Conclusions: Perinatal factors, including MSDP, account for a small portion of the variance in aggression in childhood and adolescence. Later experiences may play a greater role in shaping adolescents' aggressive behaviour. [ABSTRACT FROM AUTHOR]

Aims To determine (1) the prospective associations of conduct problems during early adolescence with tobacco, alcohol and cannabis use in young adulthood and (2) to what extent these associations are due to overlapping genetic versus environmental influences. Design A prospective twin study using biometric twin modelling. Setting Finland. Participants A total of 1847 Finnish twins (943 males and 904 females) were interviewed in early adolescence, 73% of whom ( n = 1353, 640 males and 713 females) were retained in young adulthood. Measurements Symptom counts of conduct disorder (CD) criteria were obtained from a semi-structured clinical interview in early adolescence [age 14-15 years, mean = 14.2, standard deviation (SD) = 0.15]. Frequency of alcohol, tobacco and cannabis use was obtained from a semi-structured clinical interview in young adulthood (age 19.9-26.6 years, mean = 22.4, SD = 0.7). Findings We found modest to moderate phenotypical correlations ( r = 0.16-0.35) between early adolescent CD symptoms and substance use in young adulthood. In males, the phenotypical correlations of CD symptoms with all three substance use variables are explained largely by overlapping genetic influences. In females, overlapping shared environmental influences predominantly explain the phenotypical correlation between CD symptoms and tobacco and cannabis use. Conclusions Conduct disorder symptoms in early adolescence appear to moderately predict substance use in early adulthood. In males, genetic influences seem to be most important in explaining the relationship between conduct disorder symptoms and substance use whereas in females, shared environmental influences seem to be most important. [ABSTRACT FROM AUTHOR]

Background Both alcohol-specific genetic factors and genetic factors related to externalizing behavior influence problematic alcohol use. Little is known, however, about the etiologic role of these 2 components of genetic risk on alcohol-related behaviors across development. Prior studies conducted in a male cohort of twins suggest that externalizing genetic factors are important for predicting heavy alcohol use in adolescence, whereas alcohol-specific genetic factors increase in importance during the transition to adulthood. In this report, we studied twin brothers and sisters and brother-sister twin pairs to examine such developmental trajectories and investigate whether sex and cotwin sex effects modify these genetic influences. Methods We used prospective, longitudinal twin data collected between ages 12 and 22 within the population-based FinnTwin12 cohort study (analytic n = 1,864). Our dependent measures of alcohol use behaviors included alcohol initiation (age 12), intoxication frequency (ages 14 and 17), and alcohol dependence criteria (age 22). Each individual's genetic risk of alcohol use disorders ( AUD- GR) was indexed by his/her parents' and cotwin's DSM- IV Alcohol Dependence ( AD) criterion counts. Likewise, each individual's genetic risk of externalizing disorders ( EXT- GR) was indexed with a composite measure of parents' and cotwin's DSM- IV Conduct Disorder and Antisocial Personality Disorder criterion counts. Results EXT- GR was most strongly related to alcohol use behaviors during adolescence, while AUD- GR was most strongly related to alcohol problems in young adulthood. Further, sex of the twin and sex of the cotwin significantly moderated the associations between genetic risk and alcohol use behaviors across development: AUD- GR influenced early adolescent alcohol use behaviors in females more than in males, and EXT- GR influenced age 22 AD more in males than in females. In addition, the associations of AUD- GR and EXT- GR with intoxication frequency were greater among 14- and 17-year-old females with twin brothers. Conclusions We found divergent developmental trajectories for alcohol-specific and externalizing behavior-related genetic influences on alcohol use behaviors; in early adolescence, genetic influences on alcohol use behaviors are largely nonspecific, and later in adolescence and young adulthood, alcohol-specific genetic influences on alcohol use are more influential. Importantly, within these overall trajectories, several interesting sex differences emerged. We found that the relationship between genetic risk and problematic drinking across development is moderated by the individual's sex and his/her cotwin's sex. AUD- GR influenced adolescent alcohol outcomes in females more than in males and by age 22, EXT- GR influenced AD criteria more for males than females. In addition, the association between genetic risk and intoxication frequency was greater among 14- and 17-year-old females with male cotwins. [ABSTRACT FROM AUTHOR]

Alcohol problems represent a classic example of a complex behavioral outcome that is likely influenced by many genes of small effect. A polygenic approach, which examines aggregate measured genetic effects, can have predictive power in cases where individual genes or genetic variants do not. In the current study, we first tested whether polygenic risk for alcohol problems--derived from genome-wide association estimates of an alcohol problems factor score from the age 18 assessment of the Avon Longitudinal Study of Parents and Children (ALSPAC; n = 4304 individuals of European descent; 57% female)--predicted alcohol problems earlier in development (age 14) in an independent sample (FinnTwin12; n = 1162; 53% female). We then tested whether environmental factors (parental knowledge and peer deviance) moderated polygenic risk to predict alcohol problems in the FinnTwin12 sample. We found evidence for both polygenic association and for additive polygene-environment interaction. Higher polygenic scores predicted a greater number of alcohol problems (range of Pearson partial correlations 0.07-0.08, all p-values = 0.01). Moreover, genetic influences were significantly more pronounced under conditions of low parental knowledge or high peer deviance (unstandardized regression coefficients (b), p-values (p), and percent of variance (R²) accounted for by interaction terms: b = 1.54, p = 0.02, R² = 0.33%; b = 0.94, p = 0.04, R² = 0.30%, respectively). Supplementary set-based analyses indicated that the individual top single nucleotide polymorphisms (SNPs) contributing to the polygenic scores were not individually enriched for gene-environment interaction. Although the magnitude of the observed effects are small, this study illustrates the usefulness of polygenic approaches for understanding the pathways by which measured genetic predispositions come together with environmental factors to predict complex behavioral outcomes. [ABSTRACT FROM AUTHOR]

Background Studies suggest that better cognitive and verbal abilities in childhood predict earlier experimentation with alcohol and higher levels of drinking in adolescence, whereas poorer ability is related to a higher likelihood of remaining abstinent. Whether individual differences in language development in childhood predict differences in adolescent drinking behaviors has not been studied. Methods To address that question, we compared co-twins from twin pairs discordant for their childhood language development and studied associations of parental reports of within-pair differences in age at speaking words, age at learning to read, and expressive language skills during school age with self-reported within-pair differences in drinking, intoxication, and alcohol-related problems across adolescence and young adulthood. Data from 2 longitudinal population-based samples of twin families were used, with verbal developmental differences in childhood reported by the parents when the twins were 12 and 16 years of age, respectively. Results Conditional logistic regression analyses and within-pair correlation analyses suggested positive associations between verbal development and drinking behaviors in both data sets. In analyses adjusted for birth order and birth weight, the co-twin reported to be verbally more advanced in childhood tended to report more frequent drinking and intoxication in adolescence in both samples. Better verbal development also was associated with the likelihood of having friends who drink in adolescence. Conclusions These findings suggest that, adjusting for familial and other factors shared by co-twins, better verbal development in childhood predicts more frequent drinking and intoxication in adolescence and young adulthood, possibly due, in part, to peer associations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aims: The study aimed to determine whether alcohol use during late adolescence contributes to the weight gain from adolescence to young adulthood or risk of obesity or waist circumference at young adulthood. [ABSTRACT FROM PUBLISHER]

The article presents a study on the influences of genetics and environmental factors on pubertal timing by using change in the relative height among early and late adolescence. It states that genetic effects contributed to 86 and 82% of the variance in height difference in standard deviations (HD:SDS) in girls and boys, respectively, when using similar model including additive genetic and specific environmental factors.

Background: Adolescence has been identified as a critical period with regard to the initiation and early escalation of alcohol use. Moreover, research on familial risk and protective processes provides independent support for multiple domains of parental influence on adolescent drinking; including parents’ own drinking behaviors, as well as the practices they employ to socialize their children. Despite this prevalence of findings, whether and how these distinct associations are related to one another is still not entirely clear. Methods: The present study used data from 4,731 adolescents and their parents to test the nature of associations between (a) parents’ frequencies of alcohol use and intoxication, and lifetime alcohol-related problems, (b) adolescents’ perceptions of the parenting that they receive, and (c) adolescents’ prevalence of alcohol use and intoxication at 14 and 17½ years of age. As such, multiple mediation modeling was used to assess whether parental alcohol use behaviors influence adolescent alcohol use directly, or if they operate through indirect associations with various aspects of parenting that subsequently influence adolescent use. Results: Examination of simple associations demonstrated that maternal and paternal alcohol use behaviors were positively linked with adolescent use behaviors at 14 and 17½ years of age. Likewise, several parenting behaviors were independently associated with both parental and adolescent drinking. Examined collectively, multivariate path analyses indicated that associations between parents’ and adolescents’ alcohol-related behaviors were mediated, in part, by adolescents’ perceptions of the parenting that they received, especially at 14 years of age. Furthermore, perceived parental monitoring and discipline had unique mediating capabilities, net the effects of all other parenting behaviors. Conclusions: This study demonstrates that parenting is an important mediator of the association between parental and adolescent drinking practices. An important area for future research will be to study how adolescents can avoid alcohol-related problems despite being reared within a risk laden parenting environment and/or having parents who drink frequently. [ABSTRACT FROM AUTHOR]

ABSTRACTBackgroundWe analysed genetic and environmental influences on self-esteem and its stability in adolescence.MethodFinnish twins born in 1983?1987 were assessed by questionnaire at ages 14 (n=4132 twin individuals) and 17 years (n=3841 twin individuals). Self-esteem was measured using the Rosenberg global self-esteem scale and analyzed using quantitative genetic methods for twin data in the Mx statistical package.ResultsThe heritability of self-esteem was 0?62 [95% confidence interval (CI) 0?56?0?68] in 14-year-old boys and 0?40 (95% CI 0?26?0?54) in 14-year-old girls, while the corresponding estimates at age 17 were 0?48 (95% CI 0?39?0?56) and 0?29 (95% CI 0?11?0?45). Rosenberg self-esteem scores at ages 14 and 17 were modestly correlated (r=0?44 in boys, r=0?46 in girls). In boys, the correlation was mainly (82%) due to genetic factors, with residual co-variation due to unique environment. In girls, genetic (31%) and common environmental (61%) factors largely explained the correlation.ConclusionsIn adolescence, self-esteem seems to be differently regulated in boys versusgirls. A key challenge for future research is to identify environmental influences contributing to self-esteem during adolescence and determine how these factors interact with genetic influences. [ABSTRACT FROM AUTHOR]

Aims To control for familial confounds, we studied the association between adolescent physical activity and later smoking in twin siblings discordant for their baseline physical activity. Design and measurements In this prospective population-based twin study, we asked whether persistent physical activity/inactivity in adolescence (assessed at 16, 17 and 18.5 years) predicted questionnaire-reported daily smoking at ages 22–27. Twins who, on the three baseline questionnaires, consistently reported frequent leisure physical activity (more than three times weekly) were classified as persistent exercisers, those who exercised less than three times monthly were called persistently inactive, others were occasional exercisers. Setting Finland. Participants A total of 4240 individuals, including 1870 twin pairs. Findings In analyses of individual twins, compared to persistent activity, persistent physical inactivity predicted increased risk of daily smoking (age- and sex-adjusted odds ratio 5.53, 95% confidence interval 3.88–7.88, P < 0.001). The risk remained elevated even after excluding all those who had smoked 50 cigarettes or more life-time at baseline and adjusted for educational level in adolescence. In within-pair analyses compared to the active members of discordant twin pairs, the physically inactive co-twins had increased risk of future daily smoking (sex-adjusted odds ratio 3.39, 95% confidence interval 1.56–7.39, P = 0.002). Conclusions Persistent physical inactivity in adolescence relates to adult smoking, even after familial factors are taken into account. [ABSTRACT FROM AUTHOR]

We enrolled more than 3500 same-sex twinsfrom 5 consecutive Finnish birth cohorts into a longitudinal study as each cohort reached age 16. Twins completed the Psychopathic Deviate (Pd) Scale of the Minnesota Multiphasic Personality Inventory at baseline, Sensation Seeking Scale items as each cohort reached age 17, and later, at average ages 18.5 and 25, the Rutgers Alcohol Problem Index (RAPI). Using raw maximum likelihood estimation, we fit a Cholesky model to the 4 variables assessed at 4 ages across the 4 twin types; we estimated genetic and environmental influences on the stability of alcohol problems across development and the genetic and environmental contributions to predictive correlations between adolescent personality and later alcohol-related behavior problems. With one exception, the phenotypic, genetic, and environmental correlations were very similar for males and females. The exception was that the lagged associations of Pd and RAPI reflect a higher genetic correlation among males than females and a higher environmental correlation among females than males. Our analyses suggest that developmental changes underlying variation in alcohol problems from late adolescence to early adulthood differ for males and females. In males, the main change is decreased variation due to shared environmental effects; the magnitude of genetic effects is stable over time, and the high genetic correlation, .95, suggests that the same genetic influences are important at both ages. Among females, in contrast, genetic influences decline in magnitude from age 18 to 25, and at least part of the genetic effect evident at age 25 differs from the genetic effect evident at age 18. [ABSTRACT FROM AUTHOR]

Many people begin to consume alcohol and establish drinking patterns during adolescence, making this an important developmental period for alcohol researchers to study. Both drinking initiation and establishment of drinking patterns are influenced to varying degrees by genetic as well as environmental factors. Using twin studies conducted in Finland and other countries, researchers have analyzed the specific genetic and environmental influences as well as the gene-environment interactions that shape drinking behavior in adolescence. These studies indicate that drinking initiation is determined primarily by environmental influences, whereas the establishment of drinking patterns is determined mostly by genetic factors, which themselves are subject to moderation by the environment. [ABSTRACT FROM AUTHOR]

To examine how adolescents’ inattentive behaviour, together with parental smoking patterns, predicts smoking initiation by age 14. A prospective, longitudinal study: baseline at ages 11–12, follow-up at age 14. A population-based sample of Finnish twins, born 1983–1987, with parents and classroom teachers as additional informants. Two groups were formed, allocating the co-twins of each family into separate groups: the study sample and a replication sample. Twin individuals ( n = 4552), aged 11–12 at baseline and 14 (average 14.04 years) at follow-up. At baseline, inattentiveness was assessed with the Multidimensional Peer Nomination Inventory (MPNI, Teacher Form) and parental smoking with individual questionnaires completed by each twins’ parents; at the age 14 follow-up, adolescent smoking was assessed with a self-report questionnaire. At age 14, 57% reported never having smoked, 34% had experimented with cigarettes and 9% were current smokers. Inattentiveness and parental smoking additively predicted both experimental and current smoking in adolescence. The effects were independent of each other. The risk related to inattentiveness itself is high, but in combination with the effects of parental smoking, the probability of current smoking can rise as high as 38%, compared with 5% without these two risk factors. For prevention purposes, parental commitment to non-smoking should be emphasized. [ABSTRACT FROM AUTHOR]

— Aims: Because religiousness, a protective factor for alcohol use, is much more prevalent in rural regions, we examined its importance in explaining the differences in adolescent alcohol use found in the rural and the urban regions. In rural Ostrobothnia (hereafter referred to as the rural region), alcohol use is at the lowest level in all of Finland, whereas in Uusimaa, the urban region that surrounds Helsinki (hereafter referred to as the urban region), alcohol use is at the highest level. Methods: We analysed cross-sectional questionnaire data collected from Finnish adolescents and their mothers, during 1991–1995. Results: Abstinence was more prevalent, drinking less frequent, and religiousness higher in the rural region. In the urban region, there was but a negligible correlation between alcohol use and religiousness, whereas in the rural region, the correlation was clear, especially when abstainers were included. In modelling the relationship between region and adolescent abstinence, we found an interaction between mothers' religiousness and region: high religiousness among mothers was more protective of abstinence in the rural region. Conclusions: Our results show the importance of religiousness in explaining differences in adolescent alcohol use in regions with different religious traditions, but further studies will be required to explain why mothers' religiousness affects rates of adolescent abstinence differently in the two regions. [ABSTRACT FROM PUBLISHER]

Background: Drinking frequency escalates rapidly during adolescence. Abstinence declines markedly, and drinking monthly or more often becomes normative. Individual differences in adolescent drinking patterns are large, and some patterns are predictive of subsequent drinking problems; little, however, is known of the gene-environment interactions that create them. Methods: Five consecutive and complete birth cohorts of Finnish twins, born 1975-1979, were enrolled sequentially into a longitudinal study and assessed, with postal questionnaires, at ages 16, 17, and 18.5 years. The sample included 1786 same-sex twin pairs, of whom 1240 pairs were concordantly drinking at age 16. Maximum likelihood models were fit in longitudinal analyses of the three waves of drinking data to assess changes in genetic and environmental influences on alcohol use across adolescence. Secondary analyses contrasted twin pairs residing in rural versus those in urban environments to investigate gene-environment interactions. Results: Longitudinal analyses revealed that genetic factors influencing drinking patterns increased in importance across the 30-month period, and effects arising from common environmental influences declined. Distributions of drinking frequencies in twins residing in urban and rural environments were highly similar, but influences on drinking varied between the two environments. Genetic factors assumed a larger role among adolescents residing in urban areas, while common environmental influences were more important in rural settings. Formal modeling of the data established a significant gene-environment interaction. Conclusions: The results document the changing impact of genetic and environmental influences on alcohol use across adolescence. Importantly, the results also reveal a significant gene-environment interaction in patterns of adolescent drinking and invite more detailed analyses of the pathways and mechanisms by which environments modulate genetic effects. [ABSTRACT FROM AUTHOR]

Studies the influence of the early onset of puberty on substance use within families. Association of early menarche with earlier initiation and greater frequency of smoking and drinking; Role of personality and peer relationships in such an association; Use of novel within-family analyses.

Background and Aims Design Participants/Setting Measurements Findings Conclusions Studies on adolescent alcohol use and cognition are often unable to separate the potential causal effects of alcohol use on cognition from shared etiological influences, including genetic influences or other substance use comorbidities also known to be associated with cognition, such as nicotine use. The present study aimed to fill this gap and clarify the relationship between adolescent alcohol use and young adult cognition by accounting for both measured and unmeasured confounders.A random effects model accounting for nesting in families was used to control for measured confounders. Next, co‐twin comparisons were conducted within the full sample and in monozygotic twin pairs (MZ) to control for unmeasured genetic and environmental confounders shared by co‐twins.Participants were 812 individuals (58.6% female, 361 complete pairs, 146 MZ pairs) from the longitudinal FinnTwin12 study in Finland.Adolescent alcohol use was indexed with measures of frequency of use and intoxication averaged across ages 14 and 17. Cognitive outcomes were measured at average age 22 and included Trail Making Test, California Stroop test, Wechsler Adult Intelligence subtests (Vocabulary, Block Design, Digit Symbol), Digit Span subtest of Wechsler Memory Scale, Mental Rotation Test and Object Location Memory test. Covariates included sex, parental education, general cognitive ability, current alcohol use and nicotine use.Greater frequency of alcohol use and frequency of intoxication across adolescence was associated with decreased vocabulary scores in the co‐twin control [freq: stnd beta = −0.12, 95% confidence interval (CI) = −0.234, −0.013] and MZ only co‐twin control models (freq: stnd beta = −0.305, 95% CI = –0.523, −0.087; intox: stnd beta = −0.301, 95% CI = ‐0.528, −0.074).In Finland, there appears to be little evidence that adolescent alcohol use causes cognitive deficits in young adulthood, except modest evidence for association of higher adolescent alcohol use with lower young adult vocabulary scores. [ABSTRACT FROM AUTHOR]

ROSE, RICHARD J, and DITTO, W BLAINE A Developmental-Genetic Analysis of Common Fears from Early Adolescence to Early Adulthood CHILD DEVELOPMENT, 1983, 54, 361-368 A 51item fear survey was administered to more than 2,600 adolescents and adults, including more than 400 pairs of like-sex twins, to examine developmental patterns and genetic influences on common fears Raw data were age-sex standardized and subjected to factor analysis, and preliminary analyses of the factor scores documented both age and genetic effects Some fears habituate with age, others exhibit sensitization and, for some fears, intensity is uniform across development Genetic effects were found for all factors, but the magnitude of such effects varied Based on these initial analyses, developmental patterns of genetic and environmental influences on self-assessed fears were examined in 354 pairs of like-sex twins, ages 14-34 Hierarchical multiple regression was used to predict a twin's fearfulness from the co-twin's fear, the age and zygosity of the twin pair, and the interactions of these 3 predictors For all fear factors, co-twin's score and the interaction of co-twin's score with pair zygosity significantly contributed to the prediction of a twin's fearfulness, but the magnitude of both effects varied for different fears For 2 fear factors, Personal Death and Loved One's Misfortunes, 3-way interactions of co-twin's score, age, and zygosity were observed The findings suggest significant genetic modulation of developmental patterns in the acquisition and maintenance of some adaptive fears. [ABSTRACT FROM AUTHOR]

Introduction: Previous longitudinal research suggests that motor proficiency in early life predicts physical activity in adulthood. Familial effects including genetic and environmental factors could explain the association, but no long-term follow-up studies have taken into account potential confounding by genetic and social family background. The present twin study investigated whether childhood motor skill development is associated with leisure-time physical activity levels in adulthood independent of family background. Methods: Altogether, 1550 twin pairs from the FinnTwin12 study and 1752 twin pairs from the FinnTwin16 study were included in the analysis. Childhood motor development was assessed by the parents' report of whether one of the co-twins had been ahead of the other in different indicators of motor skill development in childhood. Leisure-time physical activity (MET·h·d-1) was self-reported by the twins in young adulthood and adulthood. Statistical analyses included conditional and ordinary linear regression models within twin pairs. Results: Using all activity-discordant twin pairs, the within-pair difference in a sum score of motor development in childhood predicted the within-pair difference in the leisure-time physical activity level in young adulthood (P < 0.001). Within specific motor development indicators, learning to stand unaided earlier in infancy predicted higher leisure-time MET values in young adulthood statistically significantly in both samples (FinnTwin12, P = 0.02; and FinnTwin16, P = 0.001) and also in the pooled data set of the FinnTwin12 and FinnTwin16 studies (P = 0.001). Having been more agile than the co-twin as a child predicted higher leisure-time MET values up to adulthood (P = 0.03). Conclusions: More advanced childhood motor development is associated with higher leisure-time MET values in young adulthood at least partly independent of family background in both men and women. [ABSTRACT FROM AUTHOR]

Background: Longitudinal studies enhance understanding of the complex reciprocal relationship between smoking and depression from adolescence to young adulthood. Examining bi-directional associations between cigarette smoking and depressive symptoms in a genetically informative twin design can help to understand whether the associations are independent of shared genetic and environmental factors.Methods: We analyzed longitudinal data on smoking and depressive symptoms in twins participating in the adolescent (mean age 17.5) and young adult (mean age 21.9) surveys of the FinnTwin12 study (maximum N = 2,954 individuals; 1,154 twin pairs). At both waves, self-reported depressive symptoms, assessed with the 10-item version of the General Behavior Inventory (GBI), and smoking status were analyzed. The bi-directional associations were first studied among individuals and then within monozygotic and dizygotic twin pairs.Results: When adjusted for multiple covariates and baseline depressive symptoms, daily smokers at age 17 had higher depressive symptom scores at age 22 than never smokers (Incidence Rate Ratio = 1.17, 95% CI: 1.03-1.33). Similarly, when adjusted for covariates and baseline smoking, higher score in GBI at age 17 was associated with an increased likelihood of being a non-daily (Relative Risk Ratio (RRR) = 1.06, 95% CI: 1.01-1.11) or daily (RRR = 1.05, 95% CI: 1.00-1.10) smoker at age 22. No associations were found in within-pair analyses, suggesting that the individual-level association is explained by shared familial liabilities.Conclusion: During the developmental period from adolescence to adulthood, cigarette smoking and depressive symptoms are reciprocally associated. However, these associations are confounded by shared genetic and other familial liabilities. [ABSTRACT FROM AUTHOR]

Introduction: Genetic factors contribute to individual differences in physical activity, but it remains uncertain whether the magnitude of the genetic effects is modified by variations in home environments. We aimed to examine to what extent the psychosocial home environment in childhood and adolescence modifies the genetic influences on leisure time physical activity in young adulthood. Methods: Participants were Finnish twins (N = 3305) who reported their leisure time physical activity at age 24 yr. The psychosocial home environment was assessed by twins at ages 12, 14, and 17 yr, as well as by their parents when the twins were age 12 yr. Gene-environment interaction modeling was performed with OpenMx software. Results: Parental ratings of positive home atmosphere as well as the twins' ratings of both positive home atmosphere at age 14 yr and lower relational tensions at ages 12 and 14 yr predicted higher leisure time physical activity levels in young adulthood (regression coefficients = 0.33-0.64). Parental perceptions as well as the twins' perceptions of positive home atmosphere at ages 14 and 17 yr increased the additive genetic variation (moderation effects: 0.55, 95% confidence interval [CI] = 0.29-0.80; 0.60, 95% CI = 0.26-1.05; and 0.52, 95% CI = 0.19-0.87, respectively). The twins' ratings of positive home atmosphere at age 12 yr and lower relational tensions at ages 12 and 14 yr increased the unique environmental variation of their subsequent physical activity (moderation effects: 0.46, 95% CI = 0.19-0.60; 0.48, 95% CI = 0.29-0.64; and 0.85, 95% CI = 0.12-0.95, respectively). Conclusions: A psychosocial home environment that is warm and supportive in childhood and adolescence not only increases the mean level of subsequent leisure time physical activity in young adulthood but also modifies the genetic and environmental variances in leisure time physical activity. [ABSTRACT FROM AUTHOR]

Abstract: Background: Because the effects of susceptibility genes on alcohol use may differ as a function of age throughout adolescence and young adulthood, prospective study designs, in addition to cross-sectional ones are needed in genetic association studies. The short, low activity allele of a polymorphism (5-HTTLPR) in the serotonin transporter gene (SLC6A4) has been related to alcohol dependence. In the current study we tested whether 5-HTTLPR genotype was associated with adolescent alcohol use both cross-sectionally and longitudinally. Methods: Non-regular drinkers (n =202) were selected from Dutch, nationwide sample of adolescents (mean age 13.4 at baseline) who were assessed across five annual waves. Latent growth curve modeling was applied to examine individual development of alcohol use over time, by estimating the initial level of alcohol use at Wave 2 (intercept), and the rate of change in alcohol use across time (slope). Results: The 5-HTTLPR short allele predicted adolescent''s growth (slope) in alcohol use over time. Adolescents with the 5-HTTLPR short allele showed larger increase in alcohol consumption than those without the 5-HTTLPR short allele. 5-HTTLPR genotype was not related to the initial level (intercept) of alcohol consumption. In all analyses we controlled for sex and personality. Conclusions: To gain more insight into the etiological role of genetic determinants of adolescent alcohol use, developmental approaches that distinguish between onset and continuation of drinking should be applied. [Copyright &y& Elsevier]

Background: Twin and family studies have demonstrated that adolescent alcohol use and behavior problems are influenced by a combination of genetic and environmental factors. More recently, studies have begun to investigate how genetic and environmental influences may interact, with efforts underway to identify specific environmental variables that moderate the expression of genetic predispositions. Previously, we have reported that community-level factors, including urban/rural residency, migration rates, and prevalence of young adults, moderate the importance of genetic effects on alcohol use in late adolescence (ages 16 to 18). Here, we extend these findings to test for moderating effects of these socioregional factors on alcohol use and behavior problems assessed in a younger sample of adolescent Finnish twins. Methods: Using data from the population-based Finnish twin study, FinnTwin12, biometric twin models were fit to data on >1,400 twin pairs to examine the significance of each of the socioregional moderating variables on alcohol use measured at age 14, and behavior problems, measured at age 12. Results: We find no evidence of a moderating role of these socioregional variables on alcohol use; however, there was significant moderation of genetic influences on behavior problems, with effects limited to girls. Genetic influences assumed greater importance in urban settings, communities with greater migration, and communities with a higher percentage of slightly older adolescents. Conclusions: The moderation effects observed on behavior problems in early adolescence paralleled the effects found on alcohol use late in adolescence in an independent sample, providing further support for the idea that behavior problems may represent an earlier manifestation of the predisposition to subsequent alcohol problems. Our findings also support the growing body of evidence suggesting that females may be more susceptible to a variety of environmental influences than males. [ABSTRACT FROM AUTHOR]