On the heritability of inspection time and its covariance with IQ: a twin study

Using the classical twin design, this study investigates the influence of genetic factors on the large phenotypic variance in inspection time (IT), and whether the well established IT–IQ association can be explained by a common genetic factor. Three hundred ninety pairs of twins (184 monozygotic, MZ; 206 dizygotic, DZ) with a mean age of 16 years participated, and 49 pairs returned approximately 3 months later for retesting. As in many IT studies, the pi figure stimulus was used and IT was estimated from the cumulative normal ogive. IT ranged from 39.4 to 774.1 ms (159±110.1 ms) with faster ITs (by an average of 26.9 ms) found in the retest session from which a reliability of .69 was estimated. Full-scale IQ (FIQ) was assessed by the Multidimensional Aptitude Battery (MAB) and ranged from 79 to 145 (111±13). The phenotypic association between IT and FIQ was confirmed (−.35) and bivariate results showed that a common genetic factor accounted for 36% of the variance in IT and 32% of the variance in FIQ. The maximum likelihood estimate of the genetic correlation was −.63. When performance and verbal IQ (PIQ & VIQ) were analysed with IT, a stronger phenotypic and genetic relationship was found between PIQ and IT than with VIQ. A large part of the IT variance (64%) was accounted for by a unique environmental factor. Further genetic factors were needed to explain the remaining variance in IQ with a small component of unique environmental variance present. The separability of a shared genetic factor influencing IT and IQ from the total genetic variance in IQ suggests that IT affects a specific subcomponent of intelligence rather than a generalised efficiency.     

A Common Genetic Factor Explains the Covariation Among ADHD ODD and CD Symptoms in 9–10 Year Old Boys and Girls

Previous studies examining the covariation among Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD) and Conduct Disorder (CD) have yielded inconsistent results. Some studies have concluded that the covariation among these symptoms is due to common genetic influences, whereas others have found a common environmental overlap. The present study investigated the genetic and environmental correlations among these three childhood disorders, based on a sample of 1,219 twins, age 9–10 years. A latent externalizing behavior factor was found to explain the covariance among ADHD, ODD and CD symptoms. Genetic influences explained more than half of the variance in this externalizing factor in both boys and girls. There were also unique genetic and environmental influences in each set of symptoms, suggesting some etiological independence of the three disorders. Our findings have implications for molecular genetic studies trying to identify susceptibility genes for these disorders. This study was funded by NIMH (R01 MH58354). Catherine Tuvblad was supported by post-doctoral stipends from the Swedish Council for Working Life and Social Research (Project 2006-1501) and the Sweden-America Foundation. Adrian Raine was supported by NIMH (Independent Scientist Award K02 MH01114-08). We thank the Southern California Twin Project staff for their assistance in collecting data, and the twins and their families for their participation.     

Neurofeedback and the Brain

Neurofeedback is an emerging neuroscience-based clinical application, and understanding the underlying principles of neurofeedback allows the therapist to provide referrals or treatment, and provides clients with a framework for understanding the process. The brain's electrical patterns are a form of behavior, modifiable through “operant conditioning,” with the excessive brain frequencies reduced, and those with a deficit are increased. The learning curve for EEG has been described (Hardt, 1975).     

Trajectories and predictors of developmental skills in healthy twins up to 24 months of age

Background

Low birth weight and low 5-min Apgar scores have been associated with developmental delay, while older maternal age is a protective factor. Little is known about trajectories and predictors of developmental skills in infant twins, who are generally born with lower birth weights, lower Apgar scores and to older mothers.

Methods

Developmental skills were assessed at 3, 6, 9, 12, 18 and 24 months using the Ages and Stages Questionnaires in 152 twins from the Birmingham Registry for Twin and Heritability Studies. Multilevel spline and linear regression models (adjusted for gestational age, gender, maternal age) were used to estimate developmental trajectories and the associations between birth weight, maternal age and Apgar scores on developmental skills.

Results

Twins performed worse than singletons on communication, gross motor, fine motor, problem solving and personal-social skills (p < 0.001). Twins caught up around 6 months (score within −1 standard deviation of norm), except on gross motor skills, which did not catch up until after the age of 12 months. A one-year increase in maternal age was significantly associated with decreases in gross motor and personal–social z-scores of up to −0.09, whereas one unit increases in Apgar score increased z-scores up to 0.90 (p < 0.01).

Conclusions

Healthy twins should be considered at a higher risk for developmental delay. Whether these results are comparable to preterm singletons, or whether there are twin-specific issues involved, should be further investigated in a study that uses a matched singleton control group.     

A twin study of spatial and non-spatial delayed response performance in middle age

Delayed alternation and object alternation are classic spatial and non-spatial delayed response tasks. We tested 632 middle-aged male veteran twins on variants of these tasks in order to compare test difficulty, measure their inter-correlation, test order effects, and estimate heritabilities (proportion of observed variance due to genetic influences). Non-spatial alternation (NSA), which may involve greater reliance on processing of subgoals, was significantly more difficult than spatial alternation (SA). Despite their similarities, NSA and SA scores were uncorrelated. NSA performance was worse when administered second; there was no SA order effect. NSA scores were modestly heritable (h(2)=.25; 26); SA was not. There was shared genetic variance between NSA scores and general intellectual ability (r(g)=.55; .67), but this also suggests genetic influences specific to NSA. Compared with findings from small, selected control samples, high "failure" rates in this community-based sample raise concerns about interpretation of brain dysfunction in elderly or patient samples.     

7-10岁学龄儿童ADHD筛查研究

用SDQ（家长版）对上海10所小学二至四年级学生进行测查,以探求被试的ADHD症状表现,锁定ADHD高风险儿童。结果：（1）男生ADHD得分偏高（p<.01）,但女生在红橙两个级别内的百分数均高于男生;（2）9岁被试的ADHD得分分布最分散,占男生ADHD红色级别的比例最大,在女生ADHD得分中均值最大;（3）红橙两个级别为高风险级别。结论：（1）9岁是ADHD症状表现最严重的年龄;（2）女生具有更高的ADHD风险;（3）ADHD高风险被试晒出率：男生14.4%,女生17.4%。     

国内注意缺陷/多动障碍儿童干预效果的元分析

对国内过去12年间的62项注意缺陷/多动障碍干预研究结果进行了元分析,结果显示：（1）国内现有的ADHD干预措施取得了显著的干预效果;（2）在不同干预措施中,药物治疗与行为疗法或认知行为疗法相结合具有最佳疗效,单独的药物治疗次之,单独的行为疗法或认知行为疗法效果较低;（3）在各种效果指标中,学业指标上的效果量是最大的,这一结果与国外已有的元分析研究发现不一致;（4）在各种效果信息来源中,来自客观观察的效果量最高,来自父母评价的效果量次之,来自教师评定的效果量最差。（5）各种干预措施在不同效果指标上有不同的表现。药物治疗对于学业和行为指标的效果最强烈,而认知行为疗法和脑电反馈疗法对认知指标的效果最明显。最后,结合干预措施的选择、效果指标的采用以及研究质量问题进行了讨论     

两亚型注意缺陷多动障碍(ADHD)儿童的内隐注意定向

研究探讨注意缺陷障碍儿童与正常儿童之间,混合型与注意缺陷型ADHD儿童之间在内源与外源注意定向功能的差异。ADHD儿童及与之匹配的正常儿童对照组分别参与了两个实验,实验一采用了内源性内隐注意定向任务,实验二采用了外源性内隐注意定向任务。研究表明：（1）ADHD儿童与正常儿童相比,在注意定向过程（注意解除、转移与施加）上有一定缺陷。（2）ADHD儿童注意定向网络功能有缺陷,与反应水平上动作准备有关的注意功能可能受损。（3）两种亚类型儿童注意定向功能缺陷模式不同。在内原定向上,混合型与注意缺陷型相比较,混合型ADHD儿童表现为有较强的反应冲动性;注意缺陷型儿童,主要表现为注意加工过程比较缓慢,注意更易涣散。在外源定向上,混合型儿童在反应的运动准备及运动控制方面的缺陷要大于注意缺陷型儿童     

儿童前瞻记忆研究述评

前瞻记忆是指对未来某一时刻完成某项或某些活动的记忆。该文主要从儿童前瞻记忆的实验范式,儿童前瞻记忆与回溯记忆的关系,注意缺陷-多动障碍（Attention- Deficit Hyperactivity Disorder,ADHD）儿童的前瞻记忆以及儿童前瞻记忆影响因素的研究等几个方面对该领域的研究加以综述分析,并对其发展趋势和前景作以预测     

激活水平对两亚型ADHD儿童反应执行与抑制能力的影响

研究选取了混合型ADHD儿童14名,注意缺陷型ADHD儿童16名以及正常儿童18名,考察了在不同激活水平下,两亚型ADHD儿童之间,及其与正常儿童之间的反应执行能力与抑制能力的异同。采用传统的go/no-go任务,并将刺激间的时间间隔设置为1秒、4秒、8秒三种条件,分别对应高、中、低三种激活水平。结果发现,(1)与正常儿童相比,ADHD儿童的反应执行能力更容易受到激活水平的影响,且两亚型ADHD儿童受到的影响模式基本一致。具体而言:在高激活水平下,ADHD儿童与正常儿童差异最小;在中、低激活水平下,ADHD儿童与正常儿童差异增大,表明ADHD儿童状态调节能力落后。(2)两亚型ADHD儿童的功能缺损模式不同,混合型儿童在状态调节和反应抑制两方面都存在缺损,且其反应抑制缺陷不受激活水平影响;注意缺陷型儿童仅在状态调节方面受损。     

Family influences on the association between sleep problems and anxiety in a large sample of pre-school aged twins

Research suggests that environmental influences are important on the association between sleep problems and anxiety in children. This study examines family influences on the association between sleep problems and anxiety in 6000+ twin pairs. Parents provided information on their twins’ anxiety and sleep problems at ages 3 and 4 years. The family influences maternal depression, life events, socio-economic status, family illness, and family disorganization, were examined using parent-report. Family disorganization and maternal depression showed the strongest correlations with sleep problems (r = .20, .21, respectively) and with anxiety (r = .24, .28). Subsequent analyses indicated that family disorganization and maternal depression (examined individually) each accounted for approximately 30% of the association between sleep problems and anxiety (r = .18). The remaining association was mainly explained by environmental factors making children in the same family alike and genetic influences. This study specifies family influences that may be important in the association between sleep problems and anxiety and highlights areas of research that may be worth pursuing in order to further understand the childhood association between sleep problems and anxiety.     

注意缺损多动障碍量表的编制

 本研究在综合国内外有关儿童行为问题的测量问卷的基础上,编制了适合我国小学生特点的《儿童注意缺损多动障碍量表》。经过预测后的修订,组成正式量表。共计34个题目,施测于5所普通小学1-6年级的433名被试。因素分析结果验证了本量表五个因子的存在,即:注意力缺损、多动、冲动、唤醒不足、角色管理失控行为,从而验证了最初的结构预想。本研究着重考察了该量表的信度和效度:其中总量表与各分量表的同质性信度在.9202-.9448之间,总量表的再测信度为.8902。对量表结构效度和实证效度的检验也取得了令人满意的结果。     

Developmental Timing of Exposure to Elevated Levels of Phenylalanine Is Associated with ADHD Symptom Expression

This study addresses attention deficit hyperactivity disorder (ADHD), with a focus on how the timing of a known biological insult affects ADHD symptom expression. The sample consists of children exposed to elevated levels of phenylalanine, either postnatally as in Phenylketonuria (PKU; n = 46) or prenatally as in Maternal PKU (MPKU; n = 15). Non-hyperphenylalaninemic siblings of children with PKU (n = 18) serve as controls. Results indicate that elevated levels of phenylalanine are associated with ADHD symptoms. The manifestations of the symptom expression are dependent on exposure timing: prenatal exposure is associated with a higher likelihood of expressing hyperactive/impulsive symptoms and postnatal exposure is associated with a higher likelihood of expressing inattentive symptoms. This toxicity is dose-dependent and higher levels of phenylalanine appear more detrimental.     

High cognitive sensitivity to activational effects of testosterone in parents of offspring with autism spectrum disorders

The existence of mild forms of autistic-like characteristics in parents of children with autism spectrum disorders (ASDs) has been defined as a broader autistic phenotype (BAP). Excessive prenatal exposure to testosterone (T) seems to play a role in its development. The aims of this study were to characterize whether ASD parents show masculinized brains or high T prenatal exposure compared to a normative population, using cognitive questionnaires, and also to examine the T level changes in response to different cognitive tasks. ASD parents were found to present higher autistic and lower empathic trait scores than controls. They also have higher T levels and magnitude of T response to cognitive tasks. Specific correlation patterns between masculinized brain types and T levels were observed only in ASD parents. Thus, it seems that first-degree relatives of people with ASD have high T levels during task performance, which, in turn, produce slight cognitive masculinization. Our findings should be considered for understanding the role of androgens in the etiology of ASD. Nevertheless, the masculinization parameters described throughout the study are subtle and require further analysis.     

Personality similarity in unrelated look-alike pairs: Addressing a twin study challenge

Numerous twin studies have demonstrated genetic influence on personality traits, yet twin methods continue to be challenged. A common misconception is that monozygotic co-twins’ personality resemblance results from similar treatment by others, due to their matched physical appearance. The present study brings unique evidence to this question by assessing the similarities in personality and self-esteem of 23 pairs of unrelated look-alike individuals. Intraclass correlations for the Big Five personality traits (r_is = −.27 to .29) and the Rosenberg Self-Esteem Scale (r_i = −. 03) demonstrated little within-pair resemblance. It is concluded that (1) MZ co-twins’ personality similarity mostly reflects their shared genes, and (2) reactive gene-environment correlation best explains MZ co-twins’ similar treatment by others.