Ten years of enhancing neuro-imaging genetics through meta-analysis: An overview from the ENIGMA Genetics Working Group

Here we review the motivation for creating the enhancing neuroimaging genetics through meta-analysis (ENIGMA) Consortium and the genetic analyses undertaken by the consortium so far. We discuss the methodological challenges, findings, and future directions of the genetics working group. A major goal of the working group is tackling the reproducibility crisis affecting “candidate gene” and genome-wide association analyses in neuroimaging. To address this, we developed harmonized analytic methods, and support their use in coordinated analyses across sites worldwide, which also makes it possible to understand heterogeneity in results across sites. These efforts have resulted in the identification of hundreds of common genomic loci robustly associated with brain structure. We have found both pleiotropic and specific genetic effects associated with brain structures, as well as genetic correlations with psychiatric and neurological diseases.     

El Registro de Gemelos de Murcia. Un recurso para la investigación sobre conductas relacionadas con la salud

Genetically informative designs and, in particular, twin studies, are the most widely used methodology to analyse the relative contribution of genetic and environmental factors to inter-individual variability. These studies basically compare the degree of phenotypical similarity between monozygotic and dizygotic twin pairs. In addition to the traditional estimate of heritability, this kind of registry enables a wide variety of analyses which are unique due to the characteristics of the sample. The Murcia Twin Registry is population-based and focused on the analysis of health-related behaviour. The observed prevalence of health problems is comparable to that of other regional and national reference samples, which guarantees its representativeness. Overall, the characteristics of the Registry facilitate developing various types of research as well as genetically informative designs, and collaboration with different initiatives and consortia.     

Effects of Social Attitude Change on Smoking Heritability

Societal attitudes and norms to female smoking changed in Spain in the mid-twentieth century from a restrictive to a tolerant, and an even pro-smoking, posture, while social attitudes remained stable for males. We explored whether this difference in gender-related social norms influenced the heritability of two tobacco use measures: lifetime smoking and number of years smoking. We used a population-based sample of 2285 twins (mean age?=?55.78; SD?=?7.45; 58% females) whose adolescence began between the mid-1950s and the early 1980s. After modeling the effect of sex and year of birth on the variance components, we observed that the impact of the genetic and shared environmental factors varied differently by birth cohort between males and females. For females, shared environment explained a higher proportion of variance than the genetic factors in older cohorts. However, this situation was inverted in the younger female cohorts. In contrast, no birth cohort effect was observed for males, where the impact of the genetic and environmental factors remained constant throughout the study period. These results suggest that heritability is larger in a permissive social environment, whereas shared-environmental factors are more relevant in a society that is less tolerant to smoking.     

Gender,Health, and Initiation of Breastfeeding

The aim of this study was to explore the associations of health, gender, and motherhood with the decisions about breastfeeding. The sample consisted of 265 pregnant women (mean age: 32.34, SD: 4.01 years) who were recruited in healthcare centers and hospitals in southeast Spain between 2010 and 2011. Mental health was measured by the 12-Item General Health Questionnaire and gender by the Conformity to Feminine Norms Inventory. Women in our sample showed a higher conformity to gender norms than women surveyed in the adaptation of the inventory to the Spanish population (t = 11.25, p < 0.001, effect estimate (Cohen’s d) = 0.59). After adjustment for covariates, women who exclusively breastfed did not differ significantly in their conformity to gender norms from those who used partial breastfeeding or bottle feeding. Although good, our expectant mothers had worse mental health than the women aged 15–44 years in the Spanish National Health Survey (t = 2.96, p < 0.001, d = 0.26). Those who partially breastfed had significantly better mental health values. Gender norms were modulators in a model of factors related to initiation of breastfeeding. This study provides information about health and social construction of gender norms.     

Continuity of Genetic Risk for Aggressive Behavior Across the Life-Course

We test whether genetic influences that explain individual differences in aggression in early life also explain individual differences across the life-course. In two cohorts from The Netherlands (N?=?13,471) and Australia (N?=?5628), polygenic scores (PGSs) were computed based on a genome-wide meta-analysis of childhood/adolescence aggression. In a novel analytic approach, we ran a mixed effects model for each age (Netherlands: 12–70 years, Australia: 16–73 years), with observations at the focus age weighted as 1, and decaying weights for ages further away. We call this approach a ‘rolling weights’ model. In The Netherlands, the estimated effect of the PGS was relatively similar from age 12 to age 41, and decreased from age 41–70. In Australia, there was a peak in the effect of the PGS around age 40 years. These results are a first indication from a molecular genetics perspective that genetic influences on aggressive behavior that are expressed in childhood continue to play a role later in life.

     

Chronic low back pain and the risk of depression or anxiety symptoms: insights from a longitudinal twin study

Background Context

Pain is commonly associated with symptoms of depression or anxiety, although this relationship is considered bidirectional. There is limited knowledge regarding causal relationships.

Genetic and Environmental Influences on Biological Essentialism,Heuristic Thinking,Need for Closure,and Conservative Values: Insights From a Survey and Twin Study

Behavior Genetics - Biological essentialism, the belief that human attributes are determined by biology, is a core component of essentialist thinking. Previous studies have shown that individual...