Showing papers in "Behavior Genetics in 2009"
Journal Article•
TL;DR: For instance, the authors found that monozygotic twins had higher concordance rates than dizygotic twins for autism spectrum disorders, attention defcit hyperactivity disorder (ADHD), developmental coordination disorder, and tic disorder.
Abstract: Objective: Autism spectrum disorders are considered to be among the most heritable mental disorders, a notion based on surprisingly sparse data from small clinical studies. Population-based studies of the heritability of other neuro-psychiatric disorders and comorbidities among them have also been sparse. The authors sought to address both of these issues. Method: Parents of all Swedish 9- and 12-year-old twin pairs born between 1992 and 2000 (N=10,895) were interviewed regarding autism spectrum disorders and associated conditions (response rate, 80%). Concordance rates and structural equation modeling were used for evaluating causes for familial aggregation and overlap between conditions. Results: Monozygotic twins had higher concordance rates than dizygotic twins for autism spectrum disorders, attention defcit hyperactivity disorder (ADHD), developmental coordination disorder, and tic disorder. Genetic effects accounted for 80% (95% CI=29-91) of the variation in liability for autism spectrum disorders, 79% (95% CI=61-88) for ADHD, 70% (95% CI=35-83) for developmental coordination disorder, and 56% (95% CI=37-68) for tic disorder. Among monozygotic co-twins of children with autism spectrum disorders, the probability of having a diagnosis of ADHD was 44%, compared with 15% for dizygotic co-twins. Differences in cross-disorder effects between monozygotic and dizygotic twins were observed for most other comorbidities, and substantial proportions of the genetic variance for autism spectrum disorders was shared with each of the other disorders. Conclusions: Different neuropsychiatric disorders seem to have a common genetic etiology, suggesting caution in the use of diagnostic entities and proband status in efforts to uncover genes predisposing to autism spectrum disorders.
574 citations
TL;DR: It is argued that there is a lack of justification for performing parametric statistical procedures on INTs with the exceptions of simple designs with moderate to large sample sizes, which makes permutation testing computationally infeasible and where maximum likelihood testing is used.
Abstract: Many complex traits studied in genetics have markedly non-normal distributions. This often implies that the assumption of normally distributed residuals has been violated. Recently, inverse normal transformations (INTs) have gained popularity among genetics researchers and are implemented as an option in several software packages. Despite this increasing use, we are unaware of extensive simulations or mathematical proofs showing that INTs have desirable statistical properties in the context of genetic studies. We show that INTs do not necessarily maintain proper Type 1 error control and can also reduce statistical power in some circumstances. Many alternatives to INTs exist. Therefore, we contend that there is a lack of justification for performing parametric statistical procedures on INTs with the exceptions of simple designs with moderate to large sample sizes, which makes permutation testing computationally infeasible and where maximum likelihood testing is used. Rigorous research evaluating the utility of INTs seems warranted.
250 citations
TL;DR: The clustering of the four different measures (quality of life in general, satisfaction with life, quality of life at present, and subjective happiness) was explained by an underlying additive genetic factor and an underlying non-additive genetic factor that was not moderated by either age or sex.
Abstract: Subjective Wellbeing (SWB) can be assessed with distinct measures that have been hypothesized to represent different domains of SWB. The current study assessed SWB with four different measures in a genetically informative sample of adolescent twins and their siblings aged 13-28 years (N = 5,024 subjects from 2,157 families). Multivariate genetic modeling was applied to the data to explore the etiology of individual differences in SWB measures and the association among them. Developmental trends and sex differences were examined for mean levels and the variance-covariance structure. Mean SWB levels were equal in men and women. A small negative effect of age on mean levels of SWB was found. Individual differences in SWB were accounted for by additive and non-additive genetic influences, and non-shared environment. The broad-sense heritabilities were estimated between 40 and 50%. The clustering of the four different measures (quality of life in general, satisfaction with life, quality of life at present, and subjective happiness) was explained by an underlying additive genetic factor and an underlying non-additive genetic factor. The effect of these latent genetic factors on the phenotypes was not moderated by either age or sex.
197 citations
TL;DR: Multivariate genetic modeling showed that genes influencing self-esteem, life satisfaction, and optimism are largely overlapping, and suggested that a sizeable amount of variance in the traits may be explained by environmental effects specific to each of them.
Abstract: Certain personality characteristics such as self-esteem, life satisfaction, and optimism are fundamental components of positive mental health status and well-being. There is consistent evidence that these traits tend to be substantially correlated in individuals. However, no previous studies have investigated the origin of such correlation. This research used the twin method to unravel the genetic and environmental architecture of self-esteem, life satisfaction, and optimism, along with their mutual interplay. The sample was derived from the population-based Italian Twin Register, and included 428 twin pairs, aged 23–24 years. Multivariate genetic modeling showed that genes influencing self-esteem, life satisfaction, and optimism are largely overlapping. Furthermore, results indicated that the environmental components of the traits may overlap only modestly, and suggested that a sizeable amount of variance in the traits may be explained by environmental effects specific to each of them.
166 citations
TL;DR: Depressive-like behavior was quantified in the forced-swim (FST) and tail-suspension tests (TST) in HR and C mice that had wheel access for 6 days and then were deprived of wheels on day seven prior to the FST or TST, suggesting that HR males have a predisposition for depression- like behavior.
Abstract: Dysfunction of the hypothalamic-pituitary-adrenal axis resulting in elevated baseline glucocorticoid concentrations is a hallmark of stress-related human anxiety and affective disorders, including depression. Mice from four replicate lines bred for high voluntary wheel running (HR lines) run almost three times as much as four non-selected control (C) lines, and exhibit two fold elevated baseline circulating corticosterone levels throughout the 24 h cycle. Although elevated baseline CORT may be beneficial for high locomotor activity, chronic elevations can have deleterious effects on multiple systems, and may predispose for affective disorders. Because stressful events often precede a depressive bout, we quantified depressive-like behavior in the forced-swim (FST; generation 41) and tail-suspension tests (TST; generation 47) in HR and C mice that had wheel access for 6 days and then were deprived of wheels on day seven prior to the FST or TST. Male HR spent significantly more time immobile in the FST than C, suggesting that HR males have a predisposition for depression-like behavior. Both male and female HR (generation 43) were more active than same-sex controls in both wheel running and home-cage activity across 22 h (pooling the sexes, HR/C = 2.28 and 2.66, respectively).
105 citations
TL;DR: Genetic influences accounted for most of the covariance between the variables indicating that in older adults genes predisposing to high optimism also predispose to good mental health and self-rated health.
Abstract: Optimism has been shown to be important in maintaining wellbeing into old age, but little is known about the sources of variation in optimism and its links to mental and somatic health. Optimism, mental, and self-rated health were measured in 3,053 twin individuals (501 MZF, 153 MZM, 274 DZF, 77 DZM, and 242 DZ opposite-sex twin pairs and 561 single twins) over 50 years using the life orientation test, the General Health Questionnaire and a single-item question for self-rated health. Additive genetic factors explained 36, 34, and 46% of the variation in optimism, mental, and self-rated health, respectively, with the remainder being due to non-shared environmental influences. Genetic influences accounted for most of the covariance between the variables (14-20% of the genetic variance) indicating that in older adults genes predisposing to high optimism also predispose to good mental health and self-rated health.
88 citations
TL;DR: The nature of the variation in aptitudes and exceptional talents across different domains was investigated in a population based twin sample and the genetic architecture for aptitude and talent was similar in men and women.
Abstract: The origin of individual differences in aptitude, defined as a domain-specific skill within the normal ability range, and talent, defined as a domain specific skill of exceptional quality, is under debate. The nature of the variation in aptitudes and exceptional talents across different domains was investigated in a population based twin sample. Self-report data from 1,685 twin pairs (12-24 years) were analyzed for Music, Arts, Writing, Language, Chess, Mathematics, Sports, Memory, and Knowledge. The influence of shared environment was small for both aptitude and talent. Additive and non-additive genetic effects explained the major part of the substantial familial clustering in the aptitude measures with heritability estimates ranging between .32 and .71. Heritability estimates for talents were higher and ranged between .50 and .92. In general, the genetic architecture for aptitude and talent was similar in men and women. Genetic factors contribute to a large extent to variation in aptitude and talent across different domains of intellectual, creative, and sports abilities.
87 citations
TL;DR: The data suggest that TLI has concurrent, incremental, predictive and discriminant validity, as well as ethnic differences, and a high heritability of the index in males, and applicability for genetic and other etiology-related research, and for evaluation of individual risk.
Abstract: The inability to quantify the risk for disorders, such as substance use disorders (SUD), hinders etiology research and development of targeted intervention. Based on the concept of common transmissible liability to SUD related to illicit drugs, a method enabling quantification of this latent trait has been developed, utilizing high-risk design and item response theory. This study examined properties of a SUD transmissible liability index (TLI) derived using this method. Sons of males with or without SUD were studied longitudinally from preadolescence to young adulthood. The properties of TLI, including its psychometric characteristics, longitudinal risk assessment and ethnic variation, were examined. A pilot twin study was conducted to analyze the composition of TLI’s phenotypic variance. The data suggest that TLI has concurrent, incremental, predictive and discriminant validity, as well as ethnic differences. The data suggest a high heritability of the index in males. The results suggest applicability of the method for genetic and other etiology-related research, and for evaluation of individual risk.
86 citations
TL;DR: SAL seems to display a violent form of aggressive behavior, while NC900 display ‘functional’ hyperaggression against a docile opponent in an inter-male agonistic interaction.
Abstract: The present study aims at delineating violence from aggression, using genetically selected high (SAL, TA, NC900) and low (LAL, TNA NC100) aggressive mouse strains. Unlike aggression, violence lacks intrinsic control, environmental constraints as well as functional endpoints. Conventional measures namely latency, frequency and duration were used initially to accomplish the objective of delineation using the above strains. However, these quantitative measures fail to reveal further details beyond the magnitude of differential aggression, especially within the high aggressive mouse strains. Hence, it was necessary to analyze further, the behavioral sequences that make up the agonistic encounter. Novel measures such as threat/(attack + chase) (T/AC) and offense/withdrawal (O/W) ratios, context dependency and first-order Markov chain analysis were used for the above purpose. Our present analyses reveal clear qualitative behavioral differences between the three high aggressive selection strains based on the following facets namely structure and context in an agonistic interaction. Structure refers to a detailed study of the agonistic interaction components (ritualistic display, offense and sensitivity to the opponent submission cues) between any two subjects (inter-male interaction for the present study). Context refers to the capacity to identify an opponent by nature of its state (free moving/anesthetized), sex and the environment (home/neutral territory). NC900 displayed context dependency and structurally a rich repertoire of agonistic interaction components with an opponent. SAL failed to show discrimination and its inter-male agonistic behavior is restricted to a repetitive and an opponent-insensitive pattern of attack and chase. TA was comparable to SAL in terms of the structure but sensitive to context variables. Thus, SAL seems to display a violent form of aggressive behavior, while NC900 display 'functional' hyperaggression against a docile opponent in an inter-male agonistic interaction.
76 citations
TL;DR: Two experiments correlated responses in locomotor activity were investigated and a hyperactivity disorder model of feather pecking is suggested and distance travelled was found to be significantly higher in the high feathers pecking line compared to the low feather pecks line.
Abstract: Feather pecking is a major welfare problem in egg production. Genetic lines differing in the level of feather pecking have been developed by genetic selection. In two experiments correlated responses in locomotor activity were investigated. Firstly, general locomotor activity was estimated using electronic transponders. A total of 325 pullets from three lines: an unselected control line (CON), a line selected for low levels of feather pecking (LFP) and a line selected for high levels of feather pecking (HFP) during 6 generations, were reared in mixed line groups and activity was recorded from 13 to 17 weeks of age using antennas placed in the litter. Locomotor activity was significantly higher in the HFP and significantly lower in the LFP compared to the CON line (lsmeans 0.72 vs. 0.62 vs. 0.57 records per hen per h for HFP, CON and LFP respectively). In a second experiment locomotion was recorded in 40 chickens from the LFP and the HFP line at 5 weeks of age during day time from 09.00 to 16.00 h using a very precise computer facilitated tracking system. Distance travelled was found to be significantly higher in the high feather pecking line compared to the low feather pecking line (lsmeans 122 vs. 99 m per hour in HFP and LFP respectively). These results are discussed in relation to the ontogeny of feather pecking and a hyperactivity disorder model of feather pecking is suggested.
74 citations
TL;DR: The present study confirms previous findings of sex differences in interaction effects between the 5HTTLPR polymorphism and maltreatment in the prediction of adolescent depression.
Abstract: Serotonin plays a central role in mood regulation and the development of depressive disorders. The present study investigated whether a functional polymorphism (5HTTLPR) of the serotonin transporter gene interacts with maltreatment in the prediction of depression. A cohort of 17-18 years old students (n = 1,482) anonymously completed the Survey of Adolescent Life and Health in Vestmanland 2006 and gave a saliva sample for DNA extraction. An association between maltreatment and adolescent depression was found independent of sex. When the whole population was analyzed, no main effect of 5HTTLPR in association with depression was found. When separated by sex, a significant main effect and a G x E interaction effect of the SS allele was found among girls. No gene main effect or G x E interaction effect was found among boys. The present study confirms previous findings of sex differences in interaction effects between the 5HTTLPR polymorphism and maltreatment in the prediction of adolescent depression.
TL;DR: The results suggest that rs4570625 polymorphism may play a significant role in the pathogenesis of PD, and may have a gender-dependent effect on susceptibility to PD.
Abstract: Panic disorder (PD) is a complex and heterogeneous psychiatric condition. Dysfunction within the serotonergic system has been hypothesized to play an important role in PD. The novel brain-specific serotonin synthesizing enzyme, tryptophan hydroxylase 2 (TPH2), which represents the rate-limiting enzyme of serotonin production in the brain, may therefore be of particular importance in PD. We investigated the TPH2 703G/T SNP for association with PD. Patients with PD (n = 108), and control subjects (n = 247), were genotyped for rs4570625 (TPH2 703G/T). Male and female subjects were analyzed separately. The severity of their symptoms was measured using the Spielberger state-trait anxiety inventory (STAI), panic disorder severity scale (PDSS), anxiety sensitivity index (ASI), acute panic inventory (API), and Hamilton's rating scale for depression (HAMD). The genotype and allele frequencies of the PD patients and controls were analyzed using chi(2) statistics. There was a significant difference in the allele frequency in rs4570625 between the PD patients and normal controls. The T allele was significantly less frequent in the PD patients. We also found a significant association with rs4570625 in the female subgroup. There was no difference in symptom severity among the genotypes of this polymorphism. This result suggests that rs4570625 polymorphism may play a significant role in the pathogenesis of PD. Moreover, rs4570625 may have a gender-dependent effect on susceptibility to PD. Further studies are needed to replicate the association that we observed.
TL;DR: Characterizing the outcomes related to the phenotype of exceptional cognitive abilities has been feasible in recent years due to the availability of large samples of intellectually precocious adolescents identified by modern talent searches that have been followed-up longitudinally over multiple decades.
Abstract: Characterizing the outcomes related to the phenotype of exceptional cognitive abilities has been feasible in recent years due to the availability of large samples of intellectually precocious adolescents identified by modern talent searches that have been followed-up longitudinally over multiple decades. The level and pattern of cognitive abilities, even among participants within the top 1% of general intellectual ability, are related to differential developmental trajectories and important life accomplishments: The likelihood of earning a doctorate, earning exceptional compensation, publishing novels, securing patents, and earning tenure at a top university (and the academic disciplines within which tenure is most likely to occur) all vary as a function of individual differences in cognitive abilities assessed decades earlier. Individual differences that distinguish the able (top 1 in 100) from the exceptionally able (top 1 in 10,000) during early adolescence matter in life, and, given the heritability of general intelligence, they suggest that understanding the genetic and environmental origins of exceptional abilities should be a high priority for behavior genetic research, especially because the results for extreme groups could differ from the rest of the population. In addition to enhancing our understanding of the etiology of general intelligence at the extreme, such inquiry may also reveal fundamental determinants of specific abilities, like mathematical versus verbal reasoning, and the distinctive phenotypes that contrasting ability patterns are most likely to eventuate in at extraordinary levels.
TL;DR: It is suggested that an olfactory deficit can dissociate between benign and malign global cognitive development in non-demented, very old ε4-carriers, who are at high risk of developing dementia.
Abstract: Olfactory impairments are present in common neurodegenerative disorders and predict conversion to dementia in non-demented individuals with cognitive impairment. In cognitively intact elderly, evidence is sparse regarding the role of olfactory deficits in predicting cognitive impairment. The present study investigated predictors of 5-year prospective decline in the Mini-Mental State Examination (MMSE) in a large (n = 501), population-based sample of elderly (65–90 years) individuals. All participants were genotyped for the ApoE gene, assessed for health factors, and were non-demented at the baseline assessment. After partialling out the influences of demographic and health-factors at baseline and dementia at follow-up, poor odor identification ability in combination with older age and the ApoE-e4 allele predicted larger prospective global cognitive decline. This effect could not be produced by a vocabulary test. In sum, the findings suggest that an olfactory deficit can dissociate between benign and malign global cognitive development in non-demented, very old e4-carriers, who are at high risk of developing dementia.
TL;DR: The dopamine D2 receptor (DRD2) C957T polymorphism CC genotype is associated with decreased striatal binding of DRD2 and executive function and working memory impairments in healthy adults as mentioned in this paper.
Abstract: The dopamine D2 receptor (DRD2) C957T polymorphism CC genotype is associated with decreased striatal binding of DRD2 and executive function and working memory impairments in healthy adults. We investigated the relationships between C957T and acute stress with behavioral phenotypes of impulsivity in 72 young adults randomly allocated to either an acute psychosocial stress or relaxation induction condition. Homozygotes for 957C showed increased reward responsiveness after stress induction. They were also quicker when making immediate choices on the delay discounting task when stressed, compared with homozygotes who were not stressed. No effects were found for response inhibition, a dimension of impulsivity not related to extrinsic rewards. These data suggest that C957T is associated with a reward-related impulsivity endophenotype in response to acute psychosocial stress. Future studies should examine whether the greater sensitivity of 957C homozygotes to the effects of stress is mediated through dopamine release.
TL;DR: It is concluded that genetic variation contributes substantially to high g in Australia, the Netherlands, the United Kingdom and the United States.
Abstract: Although much genetic research has addressed normal variation in intelligence, little is known about the etiology of high cognitive abilities. Using data from 11,000 twin pairs (age range = 6-71 years) from the genetics of high cognitive abilities consortium, we investigated the genetic and environmental etiologies of high general cognitive ability (g). Age-appropriate psychometric cognitive tests were administered to the twins and used to create g scores standardized within each study. Liability-threshold model fitting was used to estimate genetic and environmental parameters for the top 15% of the distribution of g. Genetic influence for high g was substantial (0.50, with a 95% confidence interval of 0.41-0.60). Shared environmental influences were moderate (0.28, 0.19-0.37). We conclude that genetic variation contributes substantially to high g in Australia, the Netherlands, the United Kingdom and the United States.
TL;DR: This article explored the influence of environmental influences associated with parental education on children's reading ability and found that resilience (high reading ability despite lower environmental support) is more strongly influenced by genotype than is high reading ability with higher environmental support.
Abstract: Moderation of the level of genetic influence on children’s high reading ability by environmental influences associated with parental education was explored in two independent samples of identical and fraternal twins from the United States and Great Britain For both samples, the heritability of high reading performance increased significantly with lower levels of parental education Thus, resilience (high reading ability despite lower environmental support) is more strongly influenced by genotype than is high reading ability with higher environmental support This result provides a coherent account when considered alongside results of previous research showing that heritability for low reading ability decreased with lower levels of parental education
TL;DR: Profound between-line differences in the sensitivity to emotional and spatial aspects of the behavioral challenge seem to reflect different motivational factors driving the rat behavior, which clearly suggests that the diverse emotional reactivity of RHA/Verh and RLA/ Verh rats is a result of different activation of the fear/anxiety circuit.
Abstract: Psychogenetically selected Roman high (RHA/Verh) and Roman low (RLA/Verh) avoidance rats constitute a well-recognized model of diverse emotional reactivity. The two Swiss lines display marked behavioral and endocrine differences in reaction to a novel environment. In our study we found that these differences are accompanied by a distinct, line-specific pattern of neuronal activation within the fear/anxiety circuit. We have compared the c-Fos protein expression in the medial prefrontal cortex (mPFC), basolateral (BLA), central (CeA), medial (MeA), and cortical (CoA) nuclei of amygdala, paraventricular nucleus of the hypothalamus (PVN), and CA1, CA2, and CA3 fields of the hippocampus upon exposure to a novel situation of different stressorgeneity (open field with illuminated center, elevated plus maze, hole board test and acute restraint). Profound between-line differences in the sensitivity to emotional and spatial aspects of the behavioral challenge were observed for tests measuring spontaneous behavior. This effect seems to reflect different motivational factors driving the rat behavior, which clearly suggests that the diverse emotional reactivity of RHA/Verh and RLA/Verh rats is a result of different activation of the fear/anxiety circuit.
TL;DR: Maternal education is positively associated with performance on a standardized test for cognitive ability in offspring and breastfeeding does not modify the effect of genetic factors in any of the three strata of maternal education.
Abstract: The effect of breastfeeding on cognitive abilities is examined in the offspring of highly educated women and compared to the effects in women with low or middle educational attainment. All offspring consisted of 12-year old mono- or dizygotic twins and this made it possible to study the effect of breastfeeding on mean cognition scores as well as the moderating effects of breastfeeding on the heritability of variation in cognition. Information on breastfeeding and cognitive ability was available for 6,569 children. Breastfeeding status was prospectively assessed in the first years after birth of the children. Maternal education is positively associated with performance on a standardized test for cognitive ability in offspring. A significant effect of breastfeeding on cognition was also observed. The effect was similar for offspring with mothers with a high, middle, and low educational level. Breast-fed children of highly educated mothers score on average 7.6 point higher on a standardized test of cognitive abilities (CITO test; range 500–550; effects size = .936) than formula-fed children of mothers with a low education. Individual differences in cognition scores are largely accounted for by additive genetic factors (80%) and breastfeeding does not modify the effect of genetic factors in any of the three strata of maternal education. Heritability was slightly lower in children with a mother with a middle-level education.
TL;DR: The maternal postnatal environment had no substantial effect on the behavioral responses of both tame and aggressive rats, but it possibly contributed to the development of the corticosterone response to restraint stress in the tame, and not theaggressive rats, i.e. these effects of cross-foster were dependent on ratling genotype.
Abstract: Two rat lines, one tame, the other aggressive, differing by many behavioral features and stress reactivity were developed by long-term selection of wild gray rats for elimination and enhancement of aggressiveness towards humans. The aim of this work was to study the role of the maternal environment in the expression of these differences between the two rat lines using the cross-fostering paradigm. Fostering of tame rats of both sexes by aggressive mothers and aggressive females by tame mothers was without effect on behavior score towards humans, but the cross-fostered aggressive males had a small, yet significant, increase in aggressiveness score. Cross-fostering revealed that exploratory behavior in the hole-board test and the acoustic startle amplitude were weakly affected by maternal interactions, although there was an effect on body weight and on the stress corticosterone response. Body weight was decreased in tame males fostered by aggressive mothers only and it was increased in cross-fostered aggressive rats of both sexes. Fostering of tame males and females by an aggressive mother enhanced almost twofold the corticosterone response immediately after stress, while fostering of aggressive ratlings of both sexes by a tame mother was without effect. The current results demonstrated that the maternal postnatal environment had no substantial effect on the behavioral responses of both tame and aggressive rats, but it possibly contributed to the development of the corticosterone response to restraint stress in the tame, and not the aggressive rats, i.e. these effects of cross-fostering were dependent on ratling genotype.
TL;DR: Simulation results indicate that analyses of ordinal and binary data can recover both the raw and standardized patterns of results, and it is demonstrated that when using binary data, constraining the total variance to unity for a given value of the moderator is sufficient to ensure identification.
Abstract: Following the publication of Purcell’s approach to the modeling of gene by environment interaction in 2002, the interest in G × E modeling in twin and family data increased dramatically. The analytic techniques described by Purcell were designed for use with continuous data. Here we explore the re-parameterization of these models for use with ordinal and binary outcome data. Analysis of binary and ordinal data within the context of a liability threshold model traditionally requires constraining the total variance to unity to ensure identification. Here, we demonstrate an alternative approach for use with ordinal data, in which the values of the first two thresholds are fixed, thus allowing the total variance to change as function of the moderator. We also demonstrate that when using binary data, constraining the total variance to unity for a given value of the moderator is sufficient to ensure identification. Simulation results indicate that analyses of ordinal and binary data can recover both the raw and standardized patterns of results. However, the scale of the results is dependent on the specification of (threshold or variance) constraints rather than the underlying distribution of liability. Example Mx scripts are provided.
TL;DR: It is concluded that in relatively healthy women, genes affecting level of BMI may differ from those affecting change in BMI with age, and genetic and environmental influences explaining BMI overall level and its rate of change using a latent growth modeling approach are examined.
Abstract: Weight gain through middle age is a common phenomenon that increases the risk for different types of metabolic diseases and functional limitations later in life. This study examined genetic and environmental influences on the evolution of body mass index (BMI) in women from middle to old age. BMI was evaluated in 102 monozygotic and 114 dizygotic pairs of twin sisters from the year 1975, when they were 42.6 +/- 3.4 years-old, and thereafter in 1981, 1990, 2001 and 2004, in a total 29-year follow-up period. We examined genetic and environmental influences explaining BMI overall level and its rate of change using a latent growth modeling approach. The results showed that mean (+/-SD) BMI increased from 24.1 +/- 3.1 to 28.2 +/- 5.1 kg/m(2) during the 29-year period. The heritability of BMI showed a consistent increment across occasions, from 54% in 1975, to 72% in 2004. Genetic influences accounted for both overall BMI level (60%) and BMI rate of change (64%). Genetic and environmental correlations between BMI level and rate of change were: r(g) = 0.40 and r(e) = -0.24, respectively. We conclude that in relatively healthy women, genes affecting level of BMI may differ from those affecting change in BMI with age. These results provide a basis for identifying genetic variants for change in BMI.
TL;DR: The data indicate that the TRPV1 channel plays a role in orosensory-mediated ethanol avoidance, but that other receptor mechanisms likely also contribute to aversive oral responses to alcohol.
Abstract: Ethanol is a known oral trigeminal stimulant and recent data indicate that these effects are mediated in part by transient receptor potential channel vanilloid receptor 1 (TRPV1). The importance of this receptor in orally mediated ethanol avoidance is presently unknown. Here, we compared orosensory responding to ethanol in TRPV1-deficient and wild type mice in a brief-access paradigm that assesses orosensory influences by measuring immediate licking responses to small stimulus volumes. TRPV1−/− and control mice were tested with six concentrations of ethanol (3, 5, 10, 15, 25, 40%), capsaicin (0.003, 0.01, 0.03, 0.1, 0.3, 1 mM), sucrose (0.003, 0.01, 0.03, 0.1, 0.3, 1 M), and quinine (0.01, 0.03, 0.1, 0.3, 1, 3 mM) and psychophysical concentration-response functions were generated for each genotype and stimulus. TRPV1 knockouts displayed reduced oral avoidance responses to ethanol regardless of concentration, insensitivity to capsaicin, and little to no difference in sweet or bitter taste responding relative to wild type mice. These data indicate that the TRPV1 channel plays a role in orosensory-mediated ethanol avoidance, but that other receptor mechanisms likely also contribute to aversive oral responses to alcohol.
TL;DR: In middle childhood, symptoms of hyperactivity-impulsivity and oppositional behaviour may represent the same underlying liability, whereas the inattentive domain is more distinct, and rater bias may contribute to the overlap.
Abstract: Attention deficit hyperactivity disorder and oppositional behaviours frequently co-occur, We aimed to study the etiology of this overlap in a general population-based twin sample, assessing the symptom domains of hyperactivity-impulsivity and inattentiveness separately for their overlap with oppositionality. We further aimed to investigate whether rater bias may contribute to the overlap in previous data which used one rater only. Using parent and teacher ratings on hyperactivity-impulsivity, inattentiveness and oppositionality, and actigraph measurements of activity level, for 668 7-9-year-old twin pairs, oppositionality showed a higher overlap with hyperactivity-impulsivity (r = 0.95) than with inattentiveness (r = 0.52) and all etiological influences on hyperactivity-impulsivity were shared with those on oppositionality, indicated by a genetic correlation of 0.95 and a child-specific environmental correlation of 0.94. Actigraph data did not show an overlap with ratings of oppositionality. In middle childhood, symptoms of hyperactivity-impulsivity and oppositional behaviour may represent the same underlying liability, whereas the inattentive domain is more distinct.
TL;DR: Findings support the use of adoptive sibling designs to directly estimate shared environmental effects and implicate the existence of systematic environmental influences on behavior that are potentially detectable.
Abstract: The failure to identify specific non-shared environmental influences on behavior coupled with the belief that shared environmental factors contribute minimally to individual differences in behavior has led to the concern that major environmental determinants of behavior may be idiosyncratic, and therefore undetectable We used data on adoptive (N = 246) and biologically related (N = 130) same-sex sibling pairs (mean ages = 161 years older sibling; 138 years younger sibling) from the Sibling Interaction and Behavior Study (SIBS) to determine whether non-idiosyncratic environmental factors shared by siblings contributed to individual differences in a diverse set of behavioral outcomes Evidence for shared environmental influence was sought for eight composite measures covering a wide array of adolescent functioning: Academic Achievement, Total IQ, Substance Use Disorders, Externalizing Disorders, Internalizing Disorders, Peer Groups, Disinhibited Personality, and Negative Emotionality For six of eight composites, significant shared environmental effects, accounting for 14–22% of the variance, were observed for these same-sex sibling pairs These findings support the use of adoptive sibling designs to directly estimate shared environmental effects and implicate the existence of systematic environmental influences on behavior that are potentially detectable
TL;DR: Testing the association of APOE e4 variation with verbal and spatial memory in a sample of 70-year-olds both adjusted and non-adjusted for childhood and adult general cognitive ability confirmed that this effect relates to changes in memory ability with age.
Abstract: APOE e4-related memory deficits were reported in a normal population aged between 50 and 60 when controlling for general cognitive ability in early adulthood. This extended findings of APOE e4 effects on cognitive ability in 60-80-year-olds to a younger group and confirmed that this effect relates to changes in memory ability with age. The present study tests the association of APOE e4 variation with verbal and spatial memory in a sample of 70-year-olds both adjusted and non-adjusted for childhood and adult general cognitive ability. The 1,013 participants comprise surviving members of the 1947 Scottish Mental Survey resident in the Lothian area of Scotland. They were tested on general cognitive ability at age 11 years and followed up at about age 70 with tests of verbal (immediate and delayed) and spatial memory. General linear models were used to test the association between variation in the APOE polymorphism (e4 presence vs. absence) and memory measures. Of the eight measures tested, Spatial span forward was significantly associated with APOE e4 variation (P = 0.04) when adjusting for IQ, whereas Logical memory immediate was associated with APOE e4 variation (P = 0.04) in the analysis not controlling for IQ. Neither of these tests was significant when a correction for multiple testing was applied. APOE e4 does not influence memory abilities in a normal population of 70-year-olds.
TL;DR: Two assumptions made in the previous modeling of genotype–environment interaction were investigated: a lack of resemblance between parents for cognitive skill, and possible correlations between family income and a child’s genes because of the contribution of parental genes to both.
Abstract: In a previous paper (Harden et al. in Behav Gen 37:273–283, 2007) models of genotype–environment interaction were fitted to data from the National Merit Twin Study, resulting in evidence for an interaction: the heritability of National Merit Qualifying Test scores increased at higher levels of family income. The present paper investigates two assumptions made in the previous modeling. These were a lack of resemblance between parents for cognitive skill, and possible correlations between family income and a child’s genes because of the contribution of parental genes to both. The assumptions were found not to seriously affect estimates of the interaction effect—heritability still increased with income—but they did make a difference for other parameter estimates from the modeling. One possible explanation of the observed interaction, decreasing levels of assortative mating at higher income levels, was examined and found not to be consistent with other evidence from the study. Another possible explanation, a greater freedom of members of DZ pairs at higher income levels to follow independent interests, remained plausible.
TL;DR: Results are consistent with small genetically-mediated child effects on physical maltreatment and neglect, and none on sexual maltreatment, and all three forms of maltreatment are influenced mainly by idiosyncratic individual circumstances.
Abstract: Theory and empirical evidence suggest that children’s genetically influenced characteristics help to shape the environments they experience, including the parenting they ‘receive’. The extent of these genetically-mediated child effects on childhood maltreatment is not well known. The present study estimates the magnitude of genetically mediated child effects on maltreatment in 3,297 twins and siblings who were part of a large nationally representative sample of adolescents (ADD health). Participants in early adulthood retrospectively reported their experiences of physical and sexual maltreatment and neglect. Results are consistent with small genetically-mediated child effects on physical maltreatment and neglect, and none on sexual maltreatment, and all three forms of maltreatment are influenced mainly by idiosyncratic individual circumstances.
TL;DR: The study of twin pairs reared together from the Jena twin study of social attitudes indicates that the relationship between personality and retrospectively recalled family environment is largely genetically mediated.
Abstract: In this study we analyzed the etiology of the relationship between personality traits and retrospectively recalled family environment. The data of 226 identical and 168 fraternal twin pairs reared together from the Jena twin study of social attitudes were available. Personality traits were measured using the self- and peer report versions of the German NEO-personality inventory-revised. A German version of Blocks Environmental Questionnaire was applied to measure two broad dimensions of the family environment retrospectively: support and organization. We could replicate earlier findings that retrospective reports of these family environment dimensions were in part genetically influenced. A total of 66% of the genetic variance in support and 24% in organization could be accounted for by heritable variance in self-rated personality. That was replicated by using peer reports of personality, 41% explained genetic variance in support and 17% in organization. Environmental mediations were negligible. This indicates that the relationship between personality and retrospectively recalled family environment is largely genetically mediated.
TL;DR: The present study investigated for the first time startle behaviors across adolescence in male mice of the inbred strains C57BL/6J and DBA/2J, demonstrating that genetic factors and the early adolescent phase are critically important considerations in the design of mouse models of neuropsychiatric disturbances.
Abstract: Acoustic startle response and its plasticity, e.g., habituation and prepulse inhibition (PPI), have been extensively investigated, being altered in several neuropsychiatric disorders. Yet, little is known about the expression of startle-related behaviors during adolescence, a critical phase in the development of a variety of major neuropsychiatric pathologies. The present study investigated for the first time startle behaviors across adolescence in male mice of the inbred strains C57BL/6J and DBA/2J. Pre-pubertal (4 weeks of age) mice displayed reduced startle reactivity and altered PPI compared to adult animals (8 weeks of age), but these effects were observed only in the C57BL/6J strain. Strain differences were also clearly detected for startle response, habituation, and PPI. All effects were modulated by the intensity of the pulse stimulus and were not confounded by differences in anxiety levels. Our data demonstrate that genetic factors and the early adolescent phase are critically important considerations in the design of mouse models of neuropsychiatric disturbances.