Regional Cortical Surface Area in Adolescents: A Preliminary MRI Twin Study of Genetic and Environmental Contributions.

Cortical surface area (CSA) has particular relevance for understanding development, behavior, and the connection between brain structure and function. Little is known about genetic and environmental determinants of CSA during development. We utilized bivariate twin methods to identify global and regionally specific genetic factors which influence CSA in a preliminary sample of typically-developing adolescents, with hypotheses based on findings in middle-aged adults. Similar to previous findings, we observed high heritability for total CSA. There was also significant evidence for genetic influences on regional CSA, particularly when these were not adjusted for total CSA, with highest heritability in frontal cortex and relatively fewer genetic contributions to medial temporal cortical structures. Adjustment for total CSA reduced regional CSA heritability dramatically, but a moderate influence of genetic factors remained in some regions. Both global and regionally-specific genetic factors influence regional CSA during adolescence.

Genetic influences on resting-state functional networks: A twin study.

Alterations in resting-state networks (RSNs) are often associated with psychiatric and neurologic disorders. Given this critical linkage, it has been hypothesized that RSNs can potentially be used as endophenotypes for brain diseases. To validate this notion, a critical step is to show that RSNs exhibit heritability. However, the investigation of the genetic basis of RSNs has only been attempted in the default-mode network at the region-of-interest level, while the genetic control on other RSNs has not been determined yet. Here, we examined the genetic and environmental influences on eight well-characterized RSNs using a twin design. Resting-state functional magnetic resonance imaging data in 56 pairs of twins were collected. The genetic and environmental effects on each RSN were estimated by fitting the functional connectivity covariance of each voxel in the RSN to the classic ACE twin model. The data showed that although environmental effects accounted for the majority of variance in wide-spread areas, there were specific brain sites that showed significant genetic control for individual RSNs. These results suggest that part of the human brain functional connectome is shaped by genomic constraints. Importantly, this information can be useful for bridging genetic analysis and network-level assessment of brain disorders.

[A twin study on genetic and environmental factors of adolescents violence behaviors].

OBJECTIVE: To explore the influence of genetic and environmental factors on adolescents violence behaviors. METHODS: The violence behaviors of 111 twin pairs from Chongqing (aged from 11 to 18 years) were investigated with risk behavior questionnaire-adolescent (RBQ-A). The Parenting Styles and Dimensions Questionnaire (PSDQ) and Stressful Life Event (SLE) and the General Functioning Scale of the MacMaster Family Activity Device (FAD-GFS) were applied to assess their environment factors. Structural equation modeling was performed to evaluate the effects of the additive genetic factors (A), shared environment factors (C) and individual specific environmental factors (E) on the adolescents violence behaviors. RESULTS: The effects of A and E on adolescents violence behaviors were 0.41 (95% CI 0.19-0.58) and 0.59 (95% CI 0.42-0.81) respectively. There were significantly negative correlation between violence behaviors and authoritative-parenting-style (r = -0.140, P < 0.05), the score of adolescents violence behaviors was positively correlated with repressive-parenting-style score (r = 0.133, P < 0.05), the score of adolescents violence behaviors were not significantly correlated with the family functions, stress life events and the parenting education level and occupation. CONCLUSION: Adolescents violence behaviors were influenced by additive genetic factors and individual specific environmental factors. Environmental plays an important role. It should not been ignored that parental rearing pattern play a role in adolescents violence behaviors.

The Influence of Genetic and Environmental Factors on Anxiety among Chinese Adolescents: A Twin Study.

This study explored the influence of genetic and environmental factors on adolescent anxiety. Ninety-eight monozygotic and dizygotic twins from Chongqing, China (aged 15-18 years) were assessed for anxiety with the Self-Rating Anxiety Scale (SAS). The Parenting Styles and Dimensions Questionnaire (PSDQ) and Strengths and Difficulties Questionnaire (SDQ) were applied to assess environmental factors. Venous blood was drawn from the twins for zygosity determination. Structural equation modeling was performed to evaluate the effects of additive genetic factors (A), common environmental factors (C), and individual-specific environmental factors (E) on adolescent anxiety. The estimates of A and E on adolescent anxiety were 0.34 (95% CI = 0.12-0.53) and 0.66 (95% CI:0.47-0.89), respectively. The environment played an important role in adolescent anxiety. Adolescent anxiety was significantly positively correlated with peer relations (r = 0.606, p < 0.05) and negatively correlated with prosocial behavior (r = 0.207, p < 0. 05). No sex differences were observed. Adolescent anxiety was influenced by both genetic and environmental factors. The individual-specific environmental factors played an important role. Consideration of these variables will facilitate the targeted and individualized implementation of specific interventions for adolescent anxiety.

A Bivariate Twin Study of Cortical Surface Area and Verbal and Nonverbal Intellectual Skills in Adolescence.

Understanding the biological basis of cognitive differences between individuals is the goal in human intelligence research. The surface area of the cortex is considered to be a key determinant of human intelligence. Adolescence is a period of development characterized by physiological, emotional, behavioral, and psychosocial changes, which is related to the recombination and optimization of the cerebral cortex, and cognitive ability changes significantly in children and adolescents. This study examined the effects of common genetic and environmental factors between the surface area of the cerebral cortex and intelligence in typical developing adolescents (twins, n = 114, age 12-18 years old). Cortical surface area data were parsed into subregions (i.e., frontal, parietal, occipital, and temporal areas) and intelligence into verbal and nonverbal skills. We found a phenotypic correlation between regional surface areas and verbal intelligence. No correlation was observed between regional surface areas and nonverbal intelligence, except for the occipital lobe and the right hemisphere. In the bivariate twin analyses, the differences in phenotypic correlation between regional surface areas and verbal intelligence were not due to unshared environmental effects or measurement error, but to genetic effects. In summary, the current study has broadened the previous genetic investigations of cognitive ability and cortical surface area.

Twins methods quantitatively explore the genetic impact on children and adolescents brain gray matter volume.

The gray matter volumes of 58 pairs of twins ranging in age from 12 to 18 were measured by MRI to explore the genetic and environmental impacts on gray matter volume in twin children and adolescents. By means of A/C/E structural equation modeling, it was found that the gray matter volume in children and adolescents was jointly affected by genetic (A: 0.89) and environmental factors while genetic factors play a greater role. The gray matter volume in frontal lobe, parietal lobe, occipital lobe and lateral temporal lobe was mainly affected by genetics (A: 0.7-0.89), where as the gray matter volume in medial temporal lobe and cingulate cortex was affected by both genetics and environment.

[Effect of hereditary and environmental factors on the executive function of twin children].

OBJECTIVE: To explore the influence of genetic and environmental factors on the executive function of twin children. METHODS: The executive function of 122 twin pairs from Chongqing (aged from 6 to 18 years) were investigated with the perseverative errors of the Wisconsin Card Sorting Test. Structural equation modeling was performed to evaluate the effects of the additive genetic factors (A), dominance genetic latent factors (D) and individual specific environmental factors (E) on the executive functions. RESULTS: The effects of D and E on perseverative errors were 0. 77 (95%CI: 0.65-0.84) and 0.23 (95%CI: 0.16-0.35), respectively. The probability of perseverative errors showed a significant negative correlation with family functioning and with the total GHQ-12 scores of the fathers and mothers (r:-0.335, -0.335, and -0.219, respectively, P<0.01). Perseverative errors were not significantly correlated with the parenting styles and stress life events. CONCLUSION: Perseverative errors are influenced by a common dominance genetic latent factor and individual specific environmental factors, but the role of environmental factors such as family functioning and parental health can not be ignored.