Biomedical subjects

Frühling V Rijsdijk

Publications and source records attributed to Frühling V Rijsdijk.

10 recordsLinked to original sources

PubMed2006

The genetic relationship between neuroticism and autonomic function in female twins.

BACKGROUND: Neuroticism is widely used as an explanatory concept in etiological research of psychopathology. In order to clarify what neuroticism actually represents, we investigated the genetic association between neuroticism and cardiovascular measures. METHOD: In 125 female twin pairs (18-30 years), electrocardiogram and continuous finger blood pressure were assessed during two rest and two mental stress conditions. Mean values for baroreflex sensitivity (BRS), heart rate variability (HRV) and inter-beat interval (IBI) were calculated for each condition. Neuroticism was assessed by multiple questionnaires. Multivariate genetic model-fitting analyses were used to investigate the genetic correlation between latent neuroticism and the cardiovascular autonomic nervous system (ANS) measures. RESULTS: Neuroticism was negatively correlated to BRS and HRV. Neuroticism was not correlated to IBI. For BRS, this phenotypical relation was entirely determined by shared genetic influences. For HRV, the genetic contribution to the phenotypical correlation was not significant, but the proportions of explained covariance showed a trend of more genetic than environmental influences on the phenotypical relationship. CONCLUSIONS: High neuroticism is associated with a deregulated ANS. Pleiotropic genetic effects may be partly responsible for this effect.

Autonomic Nervous System↗

PubMed2006

Genetic influences on baroreflex sensitivity during rest and mental stress.

OBJECTIVE: Baroreflex sensitivity (BRS) is a predictor of cardiovascular mortality and an indicator of sympathetic and parasympathetic autonomic regulation. Although the BRS is influenced by genetic factors, the evidence is limited, and it is unknown whether contributions of genes and environment to individual variation in BRS differ during rest and mental stress conditions. DESIGN AND METHODS: In 250 female twins, electrocardiogram and continuous finger blood pressure (BP) were assessed during two rest and two mental stress conditions. BRS was calculated as the mean modulus between inter-beat-interval and systolic BP. Genetic model fitting was used to investigate the relative contribution of genetic and environmental influences to individual differences in the BRS measures. RESULTS: Familial resemblance for all conditions was found which was clearly mainly due to genetic contributions. A trend was found for higher genetic influences in the mental stress conditions (42 and 45%) compared to rest conditions (14 and 22%), and higher shared environmental effects in rest conditions (14 and 16%) compared to mental stress conditions (0.5 and 1%). Although their magnitude differed, the same genetic and shared environmental factors affected individual differences in BRS in all four conditions. CONCLUSION: Genetic influences explained up to 45% of the individual variation in BRS. This considerable proportion of genetic variance would make BRS an useful candidate trait for future association and linkage studies in the search for genes influencing autonomic regulation and cardiovascular disease risk.

Adolescent↗

PubMed2006

Associations between sleep problems, anxiety, and depression in twins at 8 years of age.

OBJECTIVES: Associations between sleep and internalizing problems are complex and poorly understood. To better understand these covarying difficulties, genetic and environmental influences were estimated by using a twin design. METHODS: Three hundred 8-year-old twin pairs reported on their anxiety and depression by completing the Screen for Childhood Anxiety Related Emotional Disorders and the Children's Depression Inventory. Parents reported on their children's sleep problems by completing the Child Sleep Habits Questionnaire. RESULTS: Children reported by their parents to have different types of sleep problems self-reported more depression symptoms than those without. The correlation between total sleep-problem score and depression was moderate. That between sleep problems and anxiety was smaller and was not examined further. The association between sleep problems and depression was mainly explained by genes, and there was substantial overlap between the genes influencing sleep problems and those influencing depression. There was smaller influence from environmental factors making family members alike, and environmental factors making family members different decreased the association between sleep problems and depression. CONCLUSIONS: A range of sleep difficulties are associated with depression in school-aged children, and the overall association between the 2 difficulties may be largely influenced by genes.

Anxiety Disorders↗

PubMed2003

Regression-based sib pair linkage analysis for binary traits.

The Haseman-Elston (HE) regression method offers a mathematically and computationally simpler alternative to variance-components (VC) models for the linkage analysis of quantitative traits. However, current versions of HE regression and VC models are not optimised for binary traits. Here, we present a modified HE regression and a liability-threshold VC model for binary-traits. The new HE method is based on the regression of a linear combination of the trait squares and the trait cross-product on the proportion of alleles identical by descent (IBD) at the putative locus, for sibling pairs. We have implemented both the new HE regression-based method and have performed analytic and simulation studies to assess its type 1 error rate and power under a range of conditions. These studies showed that the new HE method is well-behaved under the null hypothesis in large samples, is more powerful than both the original and the revisited HE methods, and is approximately equivalent in power to the liability-threshold VC model.

Data Interpretation, Statistical↗

PubMed2002

Application of hierarchical genetic models to Raven and WAIS subtests: a Dutch twin study.

Hierarchical models of intelligence are highly informative and widely accepted. Application of these models to twin data, however, is sparse. This paper addresses the question of how a genetic hierarchical model fits the Wechsler Adult Intelligence Scale (WAIS) subtests and the Raven Standard Progressive test score, collected in 194 18-year-old Dutch twin pairs. We investigated whether first-order group factors possess genetic and environmental variance independent of the higher-order general factor and whether the hierarchical structure is significant for all sources of variance. A hierarchical model with the 3 Cohen group-factors (verbal comprehension, perceptual organisation and freedom-from-distractibility) and a higher-order g factor showed the best fit to the phenotypic data and to additive genetic influences (A), whereas the unique environmental source of variance (E) could be modeled by a single general factor and specifics. There was no evidence for common environmental influences. The covariation among the WAIS group factors and the covariation between the group factors and the Raven is predominantly influenced by a second-order genetic factor and strongly support the notion of a biological basis of g.

Adolescent↗

PubMed2002

Estimation of sib-pair IBD sharing and multipoint polymorphism information content by linear regression.

A simple method of estimating IBD sharing (pi) of sibling pairs from multipoint genotype data based on linear regression is presented. The new method is an extension of that developed by Fulker, Cherny, and Cardon (1995) and involves a measure of sib-pair specific information, W, defined as the difference between the unconditional variance of pi and the conditional variance of pi given the marker genotype data. When markers are not fully informative, the W method provides estimates closer to those obtained from the exact hidden Markov method (HMM) than the original Fulker method. Using W, we also derive a generalisation for the polymorphism information content (PIC) for multiple markers. This multipoint polymorphism information content (MPIC) can be evaluated at any location along a marker map and is proportional to the noncentrality parameter for linkage. We illustrate MPIC by assessing the relative information content of single nucleotide polymorphism (SNP) and microsatellite markers.

Alleles↗

PubMed2002

Analytic approaches to twin data using structural equation models.

The classical twin study is the most popular design in behavioural genetics. It has strong roots in biometrical genetic theory, which allows predictions to be made about the correlations between observed traits of identical and fraternal twins in terms of underlying genetic and environmental components. One can infer the relative importance of these 'latent' factors (model parameters) by structural equation modelling (SEM) of observed covariances of both twin types. SEM programs estimate model parameters by minimising a goodness-of-fit function between observed and predicted covariance matrices, usually by the maximum-likelihood criterion. Likelihood ratio statistics also allow the comparison of fit of different competing models. The program Mx, specifically developed to model genetically sensitive data, is now widely used in twin analyses. The flexibility of Mx allows the modelling of multivariate data to examine the genetic and environmental relations between two or more phenotypes and the modelling to categorical traits under liability-threshold models.

Chi-Square Distribution↗

PubMed2002

Temporal and reciprocal relationship between IADL/ADL disability and depressive symptoms in late life.

A strong association between functional disability and depressive symptoms in older people has frequently been reported. Some studies attribute this association to the disabling effects of depression, others to the depressogenic effects of physical health-related disability. The authors examined the reciprocal effects between depressive symptoms and functional disability and their temporal character in a community-based cohort of 753 older people with physical limitations who were assessed at yearly intervals. They compared structural equation models that differed in terms of direction and speed of effects between patient-reported disability in instrumental and basic activities of daily living (IADL/ADLs) and depressive symptoms. The association between disability and depression could be separated into three components: (a) a strong contemporaneous effect of change in disability on depressive symptoms, (b) a weaker 1-year lagged effect of change in depressive symptoms on disability (probably indirect through physical health), and (c) a weak correlation between the trait (or stable) components of depression and disability. IADL/ADL disability and depressive symptoms are thus mutually reinforcing over time. Compensatory forces like effective treatment and age-related adaptation may protect elders against this potential downward trend. To improve quality of life in elderly adults, treatment should target disability when it is new and depression when it is persistent.

Activities of Daily Living↗

PubMed2002

A twin study of genetic relationships between psychotic symptoms.

OBJECTIVE: Biometrical model fitting was applied to clinical data from twins to investigate whether operationally defined schizophrenic, schizoaffective, and manic syndromes share genetic risk factors. METHOD: Seventy-seven monozygotic and 89 same-sex dizygotic twin pairs in which the proband met the Research Diagnostic Criteria (RDC) for lifetime-ever schizophrenic, schizoaffective, or manic syndrome were ascertained from the Maudsley Twin Register in London. The syndromes were defined non-hierarchically. Correlations in liability were calculated for each syndrome in the monozygotic and dizygotic pairs and across the three pairings of schizophrenic-manic, schizophrenic-schizoaffective, and schizoaffective-manic syndromes both within probands and within pairs. For the three syndromes considered together, an independent pathway model was fitted. RESULTS: The model fitting showed significant genetic correlations between all three syndromes. There was evidence of both common and syndrome-specific genetic contributions to the variance in liability to the schizophrenic and manic syndromes, but the genetic liability to the schizoaffective syndrome was entirely shared in common with the other two syndromes. In contrast, environmental liability to the schizoaffective syndrome was not shared with the other syndromes. CONCLUSIONS: If diagnostic hierarchies are relaxed, there is a degree of overlap in the genes contributing to RDC schizophrenic, schizoaffective, and manic syndromes. Supplementing the traditional approach of assigning a single main lifetime diagnosis with information on within-person comorbidity of psychotic syndromes may provide valuable information about the familial aggregation of psychotic symptoms.

Adolescent↗

PubMedDate not supplied

A twin-study of sleep difficulties in school-aged children.

This study examines frequency, overlap, and genetic and environmental influences on sleep difficulties, which are understudied in school-aged children. The Sleep Self Report and the Children's Sleep Habits Questionnaire were completed by 300 twin pairs (aged 8 years) and their parents. Child report suggested more frequent sleep problems than parent report (e.g., regular sleep onset delay was reported by 45% of children and 17% of parents). Associations between most of the sleep difficulties were small but significant (e.g., r(s)=.16 for parent report of bedtime resistance and sleep onset delay). Twin correlations based on parent reports suggest greater genetic influence (M=50%) than those based on child self-report (M=18%). Possible rater effects should be considered when evaluating children's sleep problems.

Child↗