Biomedical subjects

Irene Rebollo

Publications and source records attributed to Irene Rebollo.

7 recordsLinked to original sources

PubMed2006

Longitudinal stability of the CBCL-juvenile bipolar disorder phenotype: A study in Dutch twins.

BACKGROUND: The Child Behavior Checklist-juvenile bipolar disorder phenotype (CBCL-JBD) is a quantitative phenotype that is based on parental ratings of the behavior of the child. The phenotype is predictive of DSM-IV characterizations of BD and has been shown to be sensitive and specific. Its genetic architecture differs from that for inattentive, aggressive, or anxious-depressed syndromes. The purpose of this study is to assess the developmental stability of the CBCL-JBD phenotype across ages 7, 10, and 12 years in a large population-based twin sample and to examine its genetic architecture. METHODS: Longitudinal data on Dutch mono- and dizygotic twin pairs (N = 8013 pairs) are analyzed to decompose the stability of the CBCL-JBD phenotype into genetic and environmental contributions. RESULTS: Heritability of the CBCL-JBD increases with age (from 63% to 75%), whereas the effects of shared environment decrease (from 20% to 8%). The stability of the CBCL-JBD phenotype is high, with correlations between .66 and .77 across ages 7, 10, and 12 years. Genetic factors account for the majority of the stability of this phenotype. There were no sex differences in genetic architecture. CONCLUSIONS: Roughly 80% of the stability in childhood CBCL-JBD is a result of additive genetic effects.

Age Factors↗

PubMed2006

Genetic analysis of anger: genetic dominance or competitive sibling interaction.

The knowledge of the causes and development of anger is still scarce. Previous studies on the sources of variance on Type A Behavior Pattern (TABP) related measures found variable heritability estimates ranging from 0.12 to 0.68, and large differences between MZ and DZ correlations. Some authors considered dominance genetic effects, competitive sibling interaction and sex differences as possible mechanisms to explain the results, but most studies lacked power. The present study uses a large sample of more than 2,500 families, with longitudinal data from MZ and DZ pairs as well as their parents, to disentangle the sources of variance on anger. Model Fitting results showed that the sources of variance differ across sexes. For males 23% of the variance is due to additive genetic effects, and 26% to dominance genetic effects. For females 34% of the variance is due to additive genetic effects, and no dominance effects are found. There was no consistent evidence to confirm the presence of competitive sibling interaction as an alternative explanation for the low correlations in DZ males. The focus of research on the prediction of coronary heart disease (CHD) risk through psychological characteristics has recently changed from the multidimensional TABP to its emotional component: Anger. Understanding the sources of individual differences on anger can help to clarify the mechanisms that link it with CHD and its possible implications for treatment and prevention.

Adolescent↗

PubMed2006

Advances in behavioral genetics modeling using Mplus: applications of factor mixture modeling to twin data.

This article discusses new latent variable techniques developed by the authors. As an illustration, a new factor mixture model is applied to the monozygotic-dizygotic twin analysis of binary items measuring alcohol-use disorder. In this model, heritability is simultaneously studied with respect to latent class membership and within-class severity dimensions. Different latent classes of individuals are allowed to have different heritability for the severity dimensions. The factor mixture approach appears to have great potential for the genetic analyses of heterogeneous populations. Generalizations for longitudinal data are also outlined.

Adult↗

PubMed2006

Phenotypic factor analysis of family data: correction of the bias due to dependency.

Twin registries form an exceptionally rich source of information that is largely unexploited for phenotypic analyses. One obstacle to straightforward phenotypic statistical analysis is the inherent dependency, which is due to the clustering of cases within families. The present simulation study gauges the degree of the bias produced by the dependency of family data on the estimates of standard errors and chi-squared, when they are treated as independent observations in a phenotypic model, and assesses the efficiency of an estimator, which corrects for dependency. When family-clustered data are used for phenotypic analysis, in treating individuals as independent, and using standard maximum likelihood estimation, there is a tendency for the chi-square statistic to be overestimated, and the standard errors of the parameters to be underestimated. The bias increases with family resemblance, due to heritability or shared environment. The source of family resemblance -- either heritability (h(2)) and/or shared environment (c(2)) -- interacts with the composition of the sample. In the absence of c(2), samples with twins, parents and spouses show the lowest bias, whereas in the presence of c(2) samples with only twins show the lowest bias. In all conditions the bias remained below 15%. The use of the 'complex option' available in Mplus (clustering corrected robust maximum likelihood estimation) reduces the bias to the levels observed when only independent cases are considered. Thus with the use of robust estimates the bias due to family dependency becomes practically negligible in all conditions of dependency. In conclusion, the present study shows that the bias due to dependency in family data does not form a serious obstacle to phenotypic data analysis.

Chi-Square Distribution↗

PubMed2006

Complex span tasks, simple span tasks, and cognitive abilities: a reanalysis of key studies.

There is great interest in the relationships between memory span tasks and cognitive abilities. However, the causes underlying their correlation remain unknown. In the present article, five key data sets were reanalyzed according to two criteria: They must consider complex span tasks (so-called working memory [WM] tasks) and simple span tasks (so-called short-term memory [STM] tasks), and they must comprise cognitive ability measures. The obtained results offer several points of interest. First, memory span tasks should be conceived from a hierarchical perspective: They comprise both general and specific components. Second, the general component explains about four times the variance explained by the specific components. Third, STM and WM measures are closely related. Fourth, STM and WM measures share the same common variance with cognitive abilities. Finally, the strong relationship usually found between memory span tasks and cognitive abilities could be tentatively interpreted by the component shared by STM and WM--namely, the capacity for temporarily preserving a reliable memory representation of any given information.

Aptitude↗

PubMed2003

[Adaptation and validation of the Health Utilities Index Mark 3 into Spanish and correction norms for Spanish population].

BACKGROUND AND OBJECTIVE: The Health Utilities Index Mark III (HUI-3) is a psychometric instrument developed to assign utilities to patients' health states. We present its Spanish adaptation and validation. Moreover, we estimate its utility in the Spanish population and compare it to Canadian patients. PATIENTS AND METHOD: The Adaptation process has been carried out following the original protocol by Furlong. A panel of experts was selected in order to warrant the process, the questionnaire translation and the training of interviewers. Two different samples were used: a modelling sample to develop the Multi Attribute Utility function (MAUF) and a directed measure sample to validate the MAUF. Both samples are representative of the Spanish population according to gender and age quota. In order to estimate the utilities associated with each health state, Visual Analogue Scale (VAS) and Standard Gamble (SG) procedures were used. The instrument's dimensionality was assessed by means of Factor Analysis, and the convergent validity was checked against EuroQoL. RESULTS: The HUI-3 Spanish version is feasible (< 2% missing values and 7.34 1.27 minutes completion time) and reliable (Cronbach's (= 0.792 in modelling sample, 0.707 in direct measure sample, and 0.760 as a whole), showing a good test-retest correlation (0.909, p < 0.001). Convergent validity is good (correlation with EuroQoL: within 0.788 and 0.793). Factor solution met 5 factors: Speech & Dexterity, Ambulation & Pain, Vision, Emotion & Cognition, and Hearing. The Spanish and Canadian utility function differed significantly; 0.07 pts, p < 0.001). CONCLUSIONS: This questionnaire can be applied to individuals or collectively, either self-administered or through an interview. Psychometric indexes are good. Differences between Spanish and Canadian utility functions suggest the need of using the specific function for each population.

Adolescent↗

PubMedDate not supplied

Genetic and environmental influences on type A behavior pattern: evidence from twins and their parents in the Netherlands Twin Register.

OBJECTIVE: There is a dose-response positive relationship between type A behavior (TABP) and cardiovascular disease-related symptoms. Estimates of heritability for TABP from previous studies vary; this might be explained by limitations in the sizes and compositions of the samples. METHODS: This study combines a large sample size, twin and parental, data from males and females, two generations of young adults and older adults, and the use of structural equation modeling (SEM) and full information maximum likelihood (FIML) estimation. To assess TABP, the Jenkins Activity Survey (JAS) was collected from MZ and DZ twins and their parents (n = 1670 twin families). Structural equation modeling is used to evaluate and estimate the effects of additive and nonadditive genetic effects, nonshared environmental effects, and competitive sibling interaction. RESULTS: Forty-five percent of the variance in TABP was the result of genetic factors (28% were additive and 17% were nonadditive). The remaining 55% of the variance was explained by environmental factors not shared by the members of the same family. Competitive sibling interaction effects were not significant. There was no evidence of sex differences either in variances or means. CONCLUSION: Understanding the sources of variance on TABP is important for therapy and prevention. According to the present results, the relevant environmental factors for the development of TABP are not shared by the members of the same family. The genetic portion of the variance is also worth considering for therapeutic purposes. Although the genetic code cannot be altered, its effects on behavior may be modifiable through the treatment of the biological mediators.

Adolescent↗