Familial confounding of internalising symptoms and obesity in adolescents and young adults; a co-twin analysis.

BACKGROUND: Obesity and internalising disorders, including depression and anxiety, often co-occur. There is evidence that familial confounding contributes to the co-occurrence of internalising disorders and obesity in adults. However, its impact on this association among young people is unclear. Our study investigated the extent to which familial factors confound the association between internalising disorders and obesity in adolescents and young adults. SUBJECTS/METHODS: We used a matched co-twin design to investigate the impact of confounding by familial factors on associations between internalising symptoms and obesity in a sample of 4018 twins aged 16 to 27 years. RESULTS: High levels of internalising symptoms compared to low levels increased the odds of obesity for the whole cohort (adjusted odds ratio [AOR] = 3.1, 95% confidence interval [CI]: 1.5, 6.8), and in females (AOR = 4.1, 95% CI 1.5, 11.1), but not in males (AOR = 2.8 95% CI 0.8, 10.0). We found evidence that internalising symptoms were associated with an increased between-pair odds of obesity (AOR 6.2, 95% CI 1.7, 22.8), using the paired analysis but not using a within-pair association, which controls for familial confounding. Sex-stratified analyses indicated high internalising symptoms were associated with increased between-pair odds of obesity for females (AOR 12.9, 95% CI 2.2, 76.8), but this attenuated to the null using within-pair analysis. We found no evidence of between or within-pair associations for males and weak evidence that sex modified the association between internalising symptoms and obesity (likelihood ratio test p = 0.051). CONCLUSIONS: Some familial factors shared by twins confound the association between internalising symptoms and obesity in adolescent and young adult females. Internalising symptoms and obesity were not associated for adolescent and young adult males. Therefore, prevention and treatment efforts should especially address familial shared determinants of obesity, particularly targeted at female adolescents and young adults with internalising symptoms and those with a family history of these disorders.

Genetics, parenting, and family functioning-What drives the development of self-control from adolescence to adulthood?

OBJECTIVE: Self-control is a meaningful predictor of crucial life outcomes. Knowingly, genes contribute substantially to differences in self-control, but behavioral genetic findings are often misinterpreted regarding environmental influences. Therefore, we reinvestigate the heritability of self-control as well as potential environmental influences, namely parenting and a chaotic home environment. METHOD: We used cross-sectional and longitudinal data from the German twin family study TwinLife (N = 3354 individuals), structured in a multicohort design in which 13-, 19-, and 25-year-old twins rated their self-control, parents' behavior, and home environment. RESULTS: Results showed increasing mean levels and 1-year stabilities for self-control accompanied by substantial genetic influences, increasing particularly from ages 19 to 25 (53% to 76%). While chaotic home environments and negative parenting were phenotypically associated with lower self-control, twin difference models revealed that differences in these individually perceived "environments" directly predicted self-control differences (ß = -0.16 to -0.28) within families when controlling for genetic and environmental similarities. CONCLUSIONS: In addition to the genetic anchoring of self-control, results indicate that environmental factors such as negative family environments are meaningful and depend on individual perceptions within families. Interventions for enhancing self-control should, therefore, rely on individual perspectives rather than objective characteristics of home environments.

Measuring Anxiety in Older Adults: Development, Diagnostic Accuracy, and Preliminary Validation of a Short-Form of the German Geriatric Anxiety Scale (GAS-G-SF).

Anxiety symptoms and anxiety disorders are highly prevalent among older adults, and are associated with considerable distress, functional impairment, and burden. Also, there is growing need for brief instruments to measure anxiety symptoms in primary care and geriatric medical settings. Therefore, the current study focuses on the development and psychometric evaluation of a short-form of the Geriatric Anxiety Scale (GAS-G), a well-established anxiety instrument for use with older adults. Study 1 draws on the original data from the GAS-G validation study (N = 242) to develop the short-form (GAS-G-SF) and determines whether the results replicate with the short-form. Study 2 extends the validation of the GAS-G-SF to a clinical sample (N = 156; 62 patients with heart disease, 94 patients with Parkinson's disease). Overall, the GAS-G-SF showed promising psychometric properties in terms of internal consistency and validity. Also, the GAS-G-SF showed good discriminatory power based on receiver operating characteristic curve analysis in both studies. These results support the utility of the GAS-G-SF as a brief assessment measure for anxiety.

SES-of-Origin and BMI in Youth: Comparing Germany and Minnesota.

Increasing obesity is a world-wide health concern. Its most commonly used indicator, body mass index (BMI), consistently shows considerable genetic and shared environmental variance throughout life, the latter particularly in youth. Several adult studies have observed less total and genetically influenced variance with higher attained SES. These studies offer clues about sources of the 'obesity epidemic' but analogous youth studies of SES-of-origin are needed. Genetic and environmental influences and moderating effects of SES may vary in countries with different health policies, lifestyles, and degrees/sources of social inequality, offering further clues to the sources of the obesity epidemic. We examined SES-of-origin moderation of BMI variance in the German TwinLife study's cohorts assessed around ages 5, 11, 17, and 23-24, and in the Minnesota Twin Family Study's (MTFS) 11- and 17-year-old birth cohorts assessed longitudinally around ages 11, 17, and 23-24, comparing male and female twins and their parents. Age for age, both sexes' means and variances were greater in MTFS than in TwinLife. We observed that SES generally moderated genetic influences, more strongly in females, similar to most adult studies of attained-SES moderation of BMI. We interpreted differences in our SES-of-origin observations in light of inevitably-missing covariance between SES-of-origin and BMI in the models, mother-father and parent-offspring BMI correlations, and parental attained-SES-BMI correlations. We suggest that one source of the present obesity epidemic is social change that amplifies expression of genes both constraining SES attainment and facilitating weight gain.

The German Twin Family Panel (TwinLife).

The German Twin Family Panel (TwinLife) is a German longitudinal study of monozygotic and dizygotic same-sex twin pairs and their families that was designed to investigate the development of social inequalities over the life course. The study covers an observation period from approximately 2014 to 2023. The target population of the sample are reared-together twins of four different age cohorts that were born in 2009/2010 (cohort 1), in 2003/2004 (cohort 2), in 1997/1998 (cohort 3) and between 1990 and 1993 (cohort 4). In the first wave, the study included data on 4097 twin families. Families were recruited in all parts of Germany so that the sample comprises the whole range of the educational, occupational and income structure. As of 2019, two face-to-face, at-home interviews and two telephone interviews have been conducted. Data from the first home and telephone interviews are already available free of charge as a scientific use-file from the GESIS data archive. This report aims to provide an overview of the study sample and design as well as constructs that are unique in TwinLife in comparison with previous twin studies - such as an assessment of cognitive abilities or information based on the children's medical records and report cards. In addition, major findings based on the data already released are displayed, and future directions of the study are presented and discussed.

Genetic and Environmental Parent-Child Transmission of Value Orientations: An Extended Twin Family Study.

Despite cross-cultural universality of core human values, individuals differ substantially in value priorities, whereas family members show similar priorities to some degree. The latter has often been attributed to intrafamilial socialization. The analysis of self-ratings on eight core values from 399 twin pairs (ages 7-11) and their biological parents (388 mothers, 249 fathers; ages 26-65) allowed the disentanglement of environmental from genetic transmission accounting for family resemblance in value orientations. Results indicated that parent-child similarity is primarily due to shared genetic makeup. The primary source of variance in value priorities represented environmental influences that are not shared by family members. These findings do not provide evidence for parental influences beyond genetic influences contributing to intrafamilial similarity in value priorities.

What Drives the Development of Social Inequality Over the Life Course? The German TwinLife Study.

The German twin family study 'TwinLife' was designed to enhance our understanding of the development of social inequalities over the life course. The interdisciplinary project investigates mechanisms of social inequalities across the lifespan by taking into account psychological as well as social mechanisms, and their genetic origin as well as the interaction and covariation between these factors. Main characteristics of the study are: (1) a multidimensional perspective on social inequalities, (2) the assessment of developmental trajectories in childhood, adolescence, and young adulthood in a longitudinal design by using (3) a combination of a multi-cohort cross-sequential and an extended twin family design, while (4) capturing a large variation of behavioral and environmental factors in a representative sample of about 4,000 German twin families. In the present article, we first introduce the theoretical and empirical background of the TwinLife study, and second, describe the design, content, and implementation of TwinLife. Since the data will be made available as scientific use file, we also illustrate research possibilities provided by this project to the scientific community.

Mental disorders and discrimination: A prospective cohort study of young twin pairs in Germany.

Background: Mental disorders and perceived discrimination share common risk factors. The association between having a mental disorder and experiencing discrimination is well-known, but the extent to which familial factors, such as genetic and shared environmental factors, might confound this association, including sex differences in familial confounding, remains unexplored. Aims: We investigated potential unmeasured familial confounding in the association between mental disorders and perceived discrimination using a matched twin study design. Method: We examined data from 2044 same-sex twin pairs (n = 4088) aged 16-25 years from the German population-based study 'TwinLife'. We applied random-effects logistic regression to within-individual and within-and-between pair models of the association between mental disorder and perceived discrimination, and used likelihood ratio tests (LRTs) to compare these models. Multivariable models were adjusted for body mass index, educational attainment, and life satisfaction. Results: There were 322 (8.1%) participants with a diagnosed mental disorder, and 15% (n = 604) of the cohort reported having experienced discrimination in the previous 12 months. Mental disorder and discrimination were associated in the adjusted within-individual model (adjusted odds ratio = 2.19, 95% confidence interval: 1.42-3.39, P<0.001). However, the within-and-between pair model showed that this association was explained by the within-pair mean (aOR = 4.24, 95% CI: 2.17-8.29, P<0.001) and not the within-pair difference (aOR = 1.26, 95% CI: 0.70-2.28, P = 0.4) of mental disorder. Therefore, this association was mostly explained by familial confounding, which is also supported by the LRTs for the unadjusted and adjusted models (P<0.001 and P = 0.03, respectively). This familial confounding was more prominent for males than females. Conclusions: Our findings show that the association between mental disorder and discrimination is at least partially explained by unmeasured familial factors. Designing family-based healthcare models and incorporating family members in interventions targeted at ameliorating mental ill-health and experiences of discrimination among adolescents may improve efficacy.

Current twin studies in Germany: report on CoSMoS, SOEP, and ChronoS.

This article summarizes the status of three recent German twin studies: CoSMoS, SOEP, and ChronoS. The German twin study on Cognitive Ability, Self-Reported Motivation, and School Achievement (CoSMoS) is a three-wave longitudinal study of monozygotic and dizygotic twins reared together, and aims to investigate predictors of and influences on school performance. In the first wave of the data collection in 2005, 408 pairs of twins aged between 7 and 11 as well as their parents participated in CoSMoS. The SOEP twin study is an extended twin study, which has combined data from monozygotic and dizygotic twins reared together with additional data from full sibling pairs, mother-child, and grandparent-child dyads who participated in the German Socio-Economic Panel (GSOEP) study. The SOEP twin project comprises about 350 twin and 950 non-twin pairs aged between 17 and 70. Data were collected between 2009 and 2010, with a focus on personality traits, wellbeing, education, employment, income, living situation, life-satisfaction, and several attitudes. The aim of the Chronotype twin study (ChronoS) was to examine genetic and environmental influences on chronotype (morningness and eveningness), coping strategies, and several aspects of the previous SOEP twin project in a sample of 301 twin pairs aged between 19 and 76 years, recruited in 2010 and 2011. Part of the ChronoS twin sample also participated in the earlier SOEP twin study, representing a second wave of assessments. We briefly describe the design and contents of these three studies as well as selected recent findings.

The Bielefeld Longitudinal Study of Adult Twins (BiLSAT).

The Bielefeld Longitudinal Study of Adult Twins (BiLSAT) is a German longitudinal study of monozygotic and dizygotic twins reared together, including more than 1,100 twin pairs aged between 14 and 80 who participated in the first wave. Data were collected at five waves of assessment between 1993 and 2009. Initially, the study focused on genetic and environmental influences on the structure and the development in adult temperament and personality. Today, the study includes a broad range of individual variables, such as personality disorders, major life goals, interests, attitudes, values, life and work satisfaction, and major life events. A special feature of this genetically informative study lies in the multiple-rater approach (i.e., self-reports and peer reports). Longitudinal multiple-rater analyses allow researchers to go beyond the basic nature-nurture decomposition of variance in self-reports examining genetic and environmental influences on stability and change in more accurately measured individual attributes. In the current article, we briefly describe the design and contents of BiLSAT as well as some recent major findings and future plans.

How did the beginnings of the global COVID-19 pandemic affect mental well-being?

The present study aims to investigate longitudinal changes in mental well-being as well as the role of individual differences in personality traits (Big Five) and the level of Personality Organisation during the first lockdown of the COVID-19 pandemic in Germany. Overall, 272 adults (Mage= 36.94, SDage= 16.46; 68.62% female, 23.45% male, 0.69% non-binary) took part in our study with four weekly surveys during the lockdown as well as a follow-up one month after restrictions were lifted. To analyse the development of mental well-being during and shortly after the first lockdown in Germany latent growth curve models (LGCM) were calculated. The considered facets of well-being differ by their trajectory. Additionally, results suggest that the lockdown did not affect all facets to the same extent. While Life Satisfaction decreases in the short term as a reaction to the lockdown, Stress and Psychological Strain were reduced after the second week of contact restrictions. When adding personality characteristics, our results showed that Neuroticism and Conscientiousness were the two dimensions associated most strongly with SWB during the first month of the pandemic. Thus, our research suggests that personality traits should be considered when analysing mental well-being.

A Log File Analysis on the Validity of Partial Solutions in Figural Matrices Tests.

As a component of many intelligence test batteries, figural matrices tests are an effective way to assess reasoning, which is considered a core ability of intelligence. Traditionally, the sum of correct items is used as a performance indicator (total solution procedure). However, recent advances in the development of computer-based figural matrices tests allow additional indicators to be considered for scoring. In two studies, we focused on the added value of a partial solution procedure employing log file analyses from a computer-based figural matrices test. In the first study (n = 198), we explored the internal validity of this procedure by applying both an exploratory bottom-up approach (using sequence analyses) and a complementary top-down approach (using rule jumps, an indicator taken from relevant studies). Both approaches confirmed that higher scores in the partial solution procedure were associated with higher structuredness in participants' response behavior. In the second study (n = 169), we examined the external validity by correlating the partial solution procedure in addition to the total solution procedure with a Grade Point Average (GPA) criterion. The partial solution procedure showed an advantage over the total solution procedure in predicting GPA, especially at lower ability levels. The implications of the results and their applicability to other tests are discussed.

Life events as environmental States and genetic traits and the role of personality: a longitudinal twin study.

The occurrence of many life events is not entirely random but genetically influenced. The current study examined the sources underlying the stability or recurrence of life events and the developmental interplay between personality traits and life events. In a longitudinal study of 338 adult twin pairs we estimated (1) the genetic and environmental sources of continuity in aggregates of life events, (2) the sources through which personality influences the experience of life events, and (3) the sources through which life events influence personality. Unlike personality which showed both genetic and environmental influences on substantial continuity over time, stability of life events was moderate and mainly influenced by genetic factors. Significant associations between personality and life events were specific to certain personality traits and qualitative aspects of life events (controllable positive, controllable negative, and less controllable negative), primarily directional from personality to life events, and basically genetically mediated. Controlled for these genetic associations, we also found some small and basically environmentally mediated effects of life events on personality traits. The results support the concept of genotype-environment correlation as a propulsive mechanism of development.

The complexity of personality: advantages of a genetically sensitive multi-group design.

Findings from many behavioral genetic studies utilizing the classical twin design suggest that genetic and non-shared environmental effects play a significant role in human personality traits. This study focuses on the methodological advantages of extending the sampling frame to include multiple dyads of relatives. We investigated the sensitivity of heritability estimates to the inclusion of sibling pairs, mother-child pairs and grandparent-grandchild pairs from the German Socio-Economic Panel Study in addition to a classical German twin sample consisting of monozygotic- and dizygotic twins. The resulting dataset contained 1.308 pairs, including 202 monozygotic and 147 dizygotic twin pairs, along with 419 sibling pairs, 438 mother-child dyads, and 102 grandparent-child dyads. This genetically sensitive multi-group design allowed the simultaneous testing of additive and non-additive genetic, common and specific environmental effects, including cultural transmission and twin-specific environmental influences. Using manifest and latent modeling of phenotypes (i.e., controlling for measurement error), we compare results from the extended sample with those from the twin sample alone and discuss implications for future research.

Genetic and environmental influences on personality profile stability: unraveling the normativeness problem.

The present study is the first to disentangle the genetic and environmental influences on personality profile stability. Spanning a period of 10 years, we analyzed the etiology of 3 aspects of profile stability (overall profile stability, distinctive profile stability, and profile normativeness) using self- and peer reports from 539 identical and 280 fraternal twins reared together. This 3-wave multirater twin design allowed us to estimate the genetic and environmental effects on latent true scores of the 3 aspects of profile stability while controlling for method effects and random error. Consistent biometric results were only found for profile normativeness, whereas overall and distinctive profile stability scores turned out to be biased. Over time, we found personality profile normativeness to be relatively stable. This stability was due to both stable genetic and nonshared environmental effects, whereas innovative variance was completely explained by nonshared environmental effects. Our findings emphasize the importance of distinguishing between the different aspects of profile stability, since overall and distinctive stability scores are likely biased due to the normativeness problem. Yet indicating a person's similarity to the average person, the normativeness of a personality profile itself has a psychological meaning beyond socially desirable responding.

Development and Validation of the Open Matrices Item Bank.

Figural matrices tasks are one of the most prominent item formats used in intelligence tests, and their relevance for the assessment of cognitive abilities is unquestionable. However, despite endeavors of the open science movement to make scientific research accessible on all levels, there is a lack of royalty-free figural matrices tests. The Open Matrices Item Bank (OMIB) closes this gap by providing free and unlimited access (GPLv3 license) to a large set of empirically validated figural matrices items. We developed a set of 220 figural matrices based on well-established construction principles commonly used in matrices tests and administered them to a sample of N = 2572 applicants to medical schools. The results of item response models and reliability analyses demonstrate the excellent psychometric properties of the items. In the discussion, we elucidate how researchers can already use the OMIB to gain access to high-quality matrices tests for their studies. Furthermore, we provide perspectives for features that could additionally improve the utility of the OMIB.

The link between preschoolers' executive function and theory of mind and the role of epistemic states.

The aim of this study was to assess the specific relation between 3- to 6-year-olds' performance on a task measuring executive function (EF), the Dimensional Change Card Sort task (DCCS), and different developmental attainments in their theory of mind (ToM) by employing a battery of scaled ToM tasks that were comparable in task format and task demands. In addition, individual differences on the temperamental dimensions emotionality, activity, sociability, and shyness were assessed by parental rating. The main findings show that children's (N=195) performance on the DCCS related to their overall performance on the ToM scale but that this relation was specific to those ToM tasks that tap children's understanding of epistemic states such as knowledge access, diverse beliefs, and false beliefs regarding content and location. The relation between children's EF and overall ToM performance remained significant after controlling for age, sentence comprehension, child temperament, and parental education. Individual differences in child activity showed consistent negative relation to EF and ToM abilities. The findings point to a differential involvement of the various EF components in reasoning about different mental concepts.

Test Preparation in Figural Matrices Tests: Focus on the Difficult Rules.

It is well documented that training the rules employed in figural matrices tests enhances test performance. Previous studies only compare experimental conditions in which all or no rules were trained and therefore ignore the particular influence of knowledge about the easy and difficult rules. With the current study, we wanted to provide some first insights into this topic. Respondents were assigned to four groups that received training for no rules, only the easy rules, only the difficult rules, or for all rules. The results show that a training only for the difficult rules was more effective than the other trainings. This applies also to performance in the easy rules that were actually not part of the training. A possible explanation for this finding is a facilitation of the solution process that is primarily driven by knowledge about the difficult rules. In conclusion, our results demonstrate that taking differences between the rules into account may provide a deeper understanding of the effects of trainings for figural matrices tests.

Do nightmares and generalized anxiety disorder in childhood and adolescence have a common genetic origin?

The present study investigated the prevalence and heritability of nightmares and their comorbidity with psychopathology in a sample (N = 1,318) of children, adolescents, and child and adolescent twins ranging in age from 4 to 17 years old. The prevalence of terrible nightmares was estimated to be 6.4%, which is similar to previous studies. There were marginal gender differences in this rate (7.7% for boys; 5.1% in girls), contrary to previous studies that purport higher rates for girls. There was little evidence for prevalence changes across age. Nightmares were highly heritable and attributed to an additive genetic influence (51%) and nonshared environmental effects (49%). There was little evidence for a shared genetic correlation for nightmares and generalized waking anxiety (Overanxious Disorder of Childhood). There was also a substantial and pervasive comorbid psychopathology for those parents who reported Strongly True on Item 59: My child has terrible nightmares on the 200-item parent-as-respondent, Coolidge Personality and Neuropsychological Inventory. Issues in estimating prevalence rates of nightmares were identified.