Etiology of Inattention and Hyperactivity/Impulsivity in a Community Sample of Twins with Learning Difficulties

A community sample of 373 8 to 18 year-old twin pairs in which at least one twin in each pair exhibited a history of learning difficulties was utilized to examine the etiology of inattention and hyperactivity/impulsivity (hyp/imp). Symptoms of attention-deficit/hyperactivity disorder (ADHD) were assessed by the DSM-III Diagnostic Interview for Children and Adolescents. Inattention and hyp/imp composite scores were created based on results of a factor analysis. Results indicated that extreme ADHD scores were almost entirely attributable to genetic influences across several increasingly extreme diagnostic cutoff scores. Extreme inattention scores were also highly heritable whether or not the proband exhibited extreme hyp/imp. In contrast, the heritability of extreme hyp/imp increased as a linear function of the number of inattention symptoms exhibited by the proband. This finding suggests that extreme hyp/imp may be attributable to different etiological influences in individuals with and without extreme inattention. If this result can be replicated in other samples, it would provide evidence that the hyp/imp symptoms exhibited by individuals with Combined Type ADHD and Predominantly Hyp/Imp Type ADHD may be attributable to different etiological influences.     

Genetic and environmental influences on the association between performance‐based self‐esteem and exhaustion: A study of the self‐worth notion of burnout

In the self‐worth model, burnout is considered to be a syndrome of performance‐based self‐esteem (PBSE) and experiences of exhaustion. Studies have shown that PBSE and burnout indices such as Pines’ Burnout Measure (BM) are associated. Whether these variables have overlapping etiologies has however not been studied before. Genetic and environmental components of covariation between PBSE and exhaustion measured with Pines’ BM were examined in a bivariate Cholesky model using data from 14,875 monozygotic and dizygotic Swedish twins. Fifty‐two per cent of the phenotypic correlation (r = 0.41) between PBSE and Pines’ BM was explained by genetics and 48% by environmental factors. The findings of the present study strengthen the assumption that PBSE should be considered in the burnout process as proposed by the self‐worth conception of burnout. The present results extend our understanding of the link between this contingent self‐esteem construct and exhaustion and provide additional information about the underlying mechanisms in terms of genetics and environment. This finding corroborates the assumed syndrome view on burnout, while it also suggests an altered view of how the syndrome emerges and how it can be alleviated.     

青少年抑郁情绪的行为遗传学研究

本研究意在探讨青少年抑郁情绪遗传率的性别和年龄差异及遗传和环境对抑郁情绪跨时间连续性的影响。508对同卵双生子, 176对同性别异卵双生子参加了两轮追踪研究, 时间间隔约为一年半(1.37±0.44)。第一轮测量双生子的年龄范围为10~18岁, 平均年龄为13.69±2.04岁, 男生比例为46.2%。采用儿童抑郁量表(CDI)对青少年的抑郁情绪进行多报告者评定。结果发现, 青少年抑郁情绪的遗传解释率不存在性别差异, 处于青春早期青少年的遗传解释率高于青春中期的青少年。遗传是影响青春早期青少年抑郁情绪持续发生的主导因素, 而环境是影响青春中期青少年抑郁情绪持续发生的主要因素。     

The shared and unique genetic relationship between mental well-being,depression and anxiety symptoms and cognitive function in healthy twins

Alterations to cognitive function are often reported with depression and anxiety symptoms, yet few studies have examined the same associations with mental well-being. This study examined the association between mental well-being, depression and anxiety symptoms and cognitive function in 1502 healthy adult monozygotic (MZ) and dizygotic (DZ) twins, and the shared/unique contribution of genetic (G) and environmental (E) variance. Using linear mixed models, mental well-being was positively associated (p?β?=?0.127), inhibition (β?=?0.096), cognitive flexibility (β?=?0.149), motor coordination (β?=?0.114) and working memory (β?=?0.156), whereas depression and anxiety symptoms were associated (p?β?=??0.134), inhibition (β?=??0.139), cognitive flexibility (β?=??0.116) and executive function (β?=??0.139). Bivariate twin modelling showed well-being shared a small environmental correlation with motor coordination and a small genetic correlation with working memory. Trivariate twin modelling showed well-being shared a small genetic correlation with inhibition, whereas depression and anxiety symptoms shared a small environmental correlation with inhibition. The remaining variance was mostly driven by unique G and/or E variance. Overall, well-being and depression and anxiety symptoms show both independent and shared relationships with cognitive functions but this is largely attributable to unique G or E variance and small shared G/E variance between pairs of variables.     

The genetics of economic risk preferences

We examine the influence of genetics on economic risk preferences by administering a measure of these preferences to monozygotic (MZ) (i.e., identical) and dizygotic (DZ) (i.e., non‐identical) twin pairs. Our analysis supports a dominant genetic effect and virtually no additive genetic effect on economic risk preferences, with the heritability of preferences estimated at 0.63. These findings suggest that over half of the variation in such preferences can be explained by genetic factors, with the remainder of the variance explained by environmental influences not shared among sibling twins. We discuss the implications of our findings for the study of individual differences in economic risk preferences. Copyright © 2009 John Wiley & Sons, Ltd.     

Prenatal attachment in future parents of twins

The present study aims at contributing to a better understanding of prenatal attachment in parents expecting twins. In particular, the relationship between prenatal attachment (measured with the Questionnaire for Antenatal Emotional Attachment) and three other psychosocial factors—the parents' psychosocial well-being and the quality of the marital relationship (respectively assessed with the General Health Questionnaire and the Relational Interactional Satisfaction Scale) and the presence of older children in the family—was investigated in both future mothers and fathers at 27 weeks of gestation. Multiple regression analysis revealed no significant relationship between the intensity of prenatal attachment and either of the three variables. For the mothers, a significant positive relationship was found between the quality of attachment on the one hand and psychosocial well-being and quality of the marital relationship on the other hand. For the fathers, the quality of attachment was only significantly predicted by the quality of the marital relationship. © 1998 John Wiley & Sons, Ltd.     

Genetic and environmental influences on aggression in 4- to 7-year-old twins

Aggressive behaviors of 38 twin pairs (21 monozygotic [MZ], 17 dizygotic [DZ]) between the ages of 4 and 7 years were assessed through mothers' ratings and observations in their homes. An observation checklist was developed in which mothers were asked to observe and report each child's specific aggressive behaviors for a total of 6 hours spread over 3 days. In particular the observations focused on the following behaviors: rejection, destructiveness, negativism, noncompliance, teasing, physical negative, insult, verbal threat, and yelling. Biometrical genetic analysis evidenced significant heritable influences on composite aggression scores in both the observation checklist and the mothers' ratings; heritability estimates varied from.24 to.94 depending on the aggression nieasnre used, with scores from the mothers' observations demonstrating smaller genetic effect than those of the parental ratings of the environmental sources of variance, within-family factors were far more important than the between-family ones. The results also yielded significant sex and zygosity differences for means of some of the specific aggressive behaviors, where males and DZ twins scored higher than females and MZ twins. It was suggested that future studies should include more detailed investigations of the context in which specific aggressive behaviors occur and the sources toward which they are directed in order to determine the extent to which different types of aggression may have different etiologies.     

The Association Between Internalizing and Externalizing Behavior in Childhood and Early Adolescence: Genetic or Environmental Common Influences?

This study analyzed the genetic and environmental influences on internalizing and externalizing behavior problems and the nature of their cooccurrence in a national Norwegian twin sample. The sample comprised 526 identical and 389 fraternal same-sexed twin pairs from five birth cohorts, aged 5-6, 8-9, 12-13, 13-14, and 14-15 years. Behavior problems were assessed by parental ratings on the Child Behavior Checklist. A model of additive genetic, shared, and nonshared environmental influences was fitted to both internalizing and externalizing behavior in four sex and age groups. The considerable covariance,r = .51 to .58, between these traits is accounted for mainly by common environmental components; this effect was most marked in the 5 to 9-year olds. Concordance rates for children scoring above 1 standard deviation from the total sample mean on the internalizing scale only, externalizing scale only, or both indicated stronger genetic influences for internalizing or externalizing problems only than for combined problems.     

运动员心理选材的遗传学基础

采用文献综述法对心理指标的遗传问题做了研究,从而为运动员的心理选材提供遗传学的支撑。心理指标的遗传属于数量遗传,目前国内外的研究大都采用双生子之间相关的研究范式和收养子女与其生父母的相关以及其养父母的相关的研究范式,来估计心理指标的遗传度。大量的研究显示,人格的遗传度的范围为0.40~0.60;智力的遗传度在0.40~0.70之间,而其他心理指标的遗传度研究较少。在心理选材时,还应特别注意遗传因素与年龄的关系,因为遗传度随年龄的增长而发展变化。