Effect of breast feeding on intelligence in children: prospective study, sibling pairs analysis, and meta-analysis

Objective To assess the importance of maternal intelligence, and the effect of controlling for it and other important confounders, in the link between breast feeding and children's intelligence. Design Examination of the effect of breast feeding on cognitive ability and the impact of a range of potential confounders, in particular maternal IQ, within a national database. Additional analyses compared pairs of siblings from the sample who were and were not breast fed. The results are considered in the context of other studies that have also controlled for parental intelligence via meta-analysis. Setting 1979 US national longitudinal survey of youth. Subjects Data on 5475 children, the offspring of 3161 mothers in the longitudinal survey. Main outcome measure IQ in children measured by Peabody individual achievement test. Results The mother's IQ was more highly predictive of breastfeeding status than were her race, education, age, poverty status, smoking, the home environment, or the child's birth weight or birth order. One standard deviation advantage in maternal IQ more than doubled the odds of breast feeding. Before adjustment, breast feeding was associated with an increase of around 4 points in mental ability. Adjustment for maternal intelligence accounted for most of this effect. When fully adjusted for a range of relevant confounders, the effect was small (0.52) and non-significant (95% confidence interval -0.19 to 1.23). The results of the sibling comparisons and meta-analysis corroborated these findings. Conclusions Breast feeding has little or no effect on intelligence in children. While breast feeding has many advantages for the child and mother, enhancement of the child's intelligence is unlikely to be among them

Paternal antisocial behavior and sons' cognitive ability : a population-based quasiexperimental study

Parents’ antisocial behavior is associated with developmental risks for the offspring but effects on cognitive ability are unknown. We used linked Swedish register data for a large sample of adolescent men (N = 1,177,173) and their parents to estimate associations between fathers’ criminal convictions and sons’ cognitive ability assessed at compulsory military conscription. Mechanisms behind the association were tested in children-of-siblings models across three types of sibling fathers (half-siblings, full-siblings, and monozygotic twins) with increasing genetic relatedness, and in quantitative genetic models. Fathers’ convictions associated with lower cognitive ability in sons (any crime: Cohen’s d = -.28; violent crimes: Cohen’s d = -.49). Adjusting for more genetic factors gradually reduced and eventually eliminated the association. Nuclear family environmental factors did not contribute to the association. Our results suggest that the association between paternal antisocial behavior and offspring cognitive ability is not causal but mostly due to underlying genetic factors.The Alfred Kordelin FoundationThe Swedish Research CouncilThe Swedish Research Council for Health, Working Life and WelfareAccepte

Violent crime : addressing causation with family-based methods

Violent crime is an important public health problem, and incurs major costs for society. The effect of interventions has so far been modest, often attributed to a research focus on risk factors for crime, but a relative lack of understanding of the causal mechanisms behind these factors. The four studies in this thesis attempt to address different aspects of the etiology of violent crime by using family-based epidemiologic methods. It has long been known that antisocial behavior runs in families. In Paper I, a nested case-control was used to quantify the familial clustering of violent crime using a linkage of several Swedish total population registers. We were able to provide precise estimates of the familial aggregation among 1st, 2nd, and 3rd degree relatives, and also adoptive relations and spouses. Familial risks were moderate to strong, and were modified by gender, socioeconomic status, type of violent crime, and age at first conviction. Familial clustering suggests that genes and/or family environment influence the propensity for violent offending. In Paper II we attempted to estimate the relative importance of these factors by calculating the heritability in mixed probit regression. Comparing results from twin, adoptee-parent, adoptee-sibling, and sibling designs, and attempting to adjust for non-random mating, we found that about half the variation in violent offending could be attributed to genetic factors. We also found significant gender differences in the etiology of violent crime. In Paper III, we discussed the interpretation of sibling comparison designs. Sibling comparisons have been hailed for their ability to adjust for family-shared confounders, but have received little attention from a methodological standpoint. In line with previous research in economy, we showed that these models are subject to several caveats, and that they may in some situations increase rather than decrease bias. The implications of this were acknowledged in Paper IV, where we analysed the association of general cognitive ability and violent crime, and adjusted for shared family characteristics through sibling comparison analysis. Taking measurement error and non-shared confounding into account, the results indicated that the association was partly confounded by factors shared by siblings, but that most of the association could not be explained by such factors. Together, Papers I and II suggested that violent crime runs in families due to both genetic and environmental factors, and Paper IV offered some support for the hypothesis that intelligence may be one of the factors explaining this familial aggregation. The caveats of sibling comparisons pointed out in Paper III should be taken into account when using co-twin control and other sibling designs to address issues of causality

Removing systematic errors for exoplanet search via latent causes

We describe a method for removing the effect of confounders in order to reconstruct a latent quantity of interest. The method, referred to as half-sibling regression, is inspired by recent work in causal inference using additive noise models. We provide a theoretical justification and illustrate the potential of the method in a challenging astronomy application.Comment: Extended version of a paper appearing in the Proceedings of the 32nd International Conference on Machine Learning, Lille, France, 201

Risk Factors for Long-Term Coronary Artery Calcium Progression in the Multi-Ethnic Study of Atherosclerosis.

BackgroundCoronary artery calcium (CAC) detected by noncontrast cardiac computed tomography scanning is a measure of coronary atherosclerosis burden. Increasing CAC levels have been strongly associated with increased coronary events. Prior studies of cardiovascular disease risk factors and CAC progression have been limited by short follow-up or restricted to patients with advanced disease.Methods and resultsWe examined cardiovascular disease risk factors and CAC progression in a prospective multiethnic cohort study. CAC was measured 1 to 4 times (mean 2.5 scans) over 10 years in 6810 adults without preexisting cardiovascular disease. Mean CAC progression was 23.9 Agatston units/year. An innovative application of mixed-effects models investigated associations between cardiovascular disease risk factors and CAC progression. This approach adjusted for time-varying factors, was flexible with respect to follow-up time and number of observations per participant, and allowed simultaneous control of factors associated with both baseline CAC and CAC progression. Models included age, sex, study site, scanner type, and race/ethnicity. Associations were observed between CAC progression and age (14.2 Agatston units/year per 10 years [95% CI 13.0 to 15.5]), male sex (17.8 Agatston units/year [95% CI 15.3 to 20.3]), hypertension (13.8 Agatston units/year [95% CI 11.2 to 16.5]), diabetes (31.3 Agatston units/year [95% CI 27.4 to 35.3]), and other factors.ConclusionsCAC progression analyzed over 10 years of follow-up, with a novel analytical approach, demonstrated strong relationships with risk factors for incident cardiovascular events. Longitudinal CAC progression analyzed in this framework can be used to evaluate novel cardiovascular risk factors

Parental characteristics and offspring internalizing behaviors : understanding the associations using quantitative genetics

Internalizing problems increase dramatically from childhood to adolescence and account for a large proportion of mental health problems worldwide. During the past decade research has documented a robust association between offspring internalizing problems and different aspects of parental characteristics, such as parenting practices and psychiatric disorders. Findings from twin and family studies have suggested that this association is influenced by both genetic and environmental factors. Nevertheless, prior studies have had limited possibilities to disentangle familial confounding from causal environmental mechanisms. Therefore, we aimed to use different genetically informative designs to explore the direction and etiology of the association between different parental characteristics and offspring internalizing behaviors. In Paper I, we examined a sample of Swedish twins to understand the direction and etiology of the association between different parenting styles and offspring internalizing behavior from adolescence to early adulthood. We found that daughters internalizing behavior influenced an emotional overinvolved behavior from their parents. Twin analyses indicated that this association was mediated by genetic factors. In Paper II, we investigated the impact of offspring death and suicide on psychiatric disorders among their parents in a cohort defined by nationwide registers. Parents exposed to offspring suicide had considerably higher risk for subsequent psychiatric hospitalization. Furthermore, a shared genetic liability for psychiatric disorder seemed important judging from family-based analyses. In Paper III, we specifically examined the suicide risk among offspring of parents hospitalized for schizophrenia and the mechanisms behind this association. We observed a doubled risk of suicidal behavior in offspring. Cousin comparisons suggested that environmental factors play an important role in this association. In Paper IV, we explored if ADHD and suicidal behavior shared genetic and environmental factors. We found an increased risk of both completed and attempted suicide among relatives of individuals with ADHD. The pattern of familial aggregation indicated genetic influences for this association. In conclusion, genetic and environmental factors contributed to the associations between parental characteristics and offspring internalizing behavior. Internalizing behaviors in offspring predicted both parenting and psychiatric disorders through genetic mechanisms. However, we could also show that specific parental psychiatric disorders predicted offspring internalizing behaviors through environmental mechanisms. In addition, we found that genetic factors for internalizing behavior to some extent is shared with genetic factors for ADHD. Future research using other genetically informative designs to control for familial confounding is necessary to provide a clearer understanding of the etiological link between parental characteristics and offspring internalizing behavior

Socioeconomic disparities in diet vary according to migration status among adolescents in Belgium

Little information concerning social disparities in adolescent dietary habits is currently available, especially regarding migration status. The aim of the present study was to estimate socioeconomic disparities in dietary habits of school adolescents from different migration backgrounds. In the 2014 cross-sectional Health Behavior in School-Aged Children survey in Belgium, food consumption was estimated using a self-administrated short food frequency questionnaire. In total, 19,172 school adolescents aged 10-19 years were included in analyses. Multilevel multiple binary and multinomial logistic regressions were performed, stratified by migration status (natives, 2nd- and 1st-generation immigrants). Overall, immigrants more frequently consumed both healthy and unhealthy foods. Indeed, 32.4% of 1st-generation immigrants, 26.5% of 2nd-generation immigrants, and 16.7% of natives consumed fish two days a week. Compared to those having a high family affluence scale (FAS), adolescents with a low FAS were more likely to consume chips and fries once a day (vs. <once a day: Natives aRRR = 1.39 (95%CI: 1.12-1.73); NS in immigrants). Immigrants at schools in Flanders were less likely than those in Brussels to consume sugar-sweetened beverages 2-6 days a week (vs. once a week: Natives aRRR = 1.86 (95%CI: 1.32-2.62); 2nd-generation immigrants aRRR = 1.52 (1.11-2.09); NS in 1st-generation immigrants). The migration gradient observed here underlines a process of acculturation. Narrower socioeconomic disparities in immigrant dietary habits compared with natives suggest that such habits are primarily defined by culture of origin. Nutrition interventions should thus include cultural components of dietary habits

The general factor of psychopathology : precursors and consequences

Comorbidity among different types of psychopathology is very common whether they are treated as discrete diagnostic categories or continuous dimensions. Empirical methods to describing these dimensions of dysfunction and their high co-occurrence have advanced our understanding and definition of mental disorders. These methods consistently show that different forms of psychopathology are correlated, resulting in the extraction of a general factor of psychopathology known as the p factor. In this thesis, we performed multivariate analyses on the nationwide Swedish registers and the Swedish twin registers to examine how the general psychopathology relates to genetics, cardiometabolic complications and pain and suicidal behavior. In study I, we explored whether psychiatric polygenic risk scores (PRS) could directly predict general and specific psychopathology. We modeled one general and seven specific factors based on childhood psychiatric symptoms, and one general and three specific factors based on adolescent psychiatric symptoms. We then regressed each general and specific factor onto ten psychiatric PRS simultaneously between and within twin pairs, the latter controls for indirect pathways (population stratification, assortative mating and dynastic effects). We found that PRS-general psychopathology associations did not appear attributable to indirect pathways, suggesting that genetics appeared to directly influence symptomatology. In study II, we examined whether the increased risk of cardiometabolic complications for mental health conditions might be attributed to a general liability toward psychopathology or confounded by unmeasured familial factors. We identified general, internalizing, externalizing, and psychotic factors based on the comorbidity among psychiatric diagnoses and criminal convictions in young adulthood. We then regressed the cardiometabolic complications in middle adulthood on the latent general factor and three uncorrelated specific factors within a structural equation modeling framework in individuals and across sibling pairs. BMI and smoking were used as mediators among child-bearing females. We found that associations between individuals with mental disorders in early life and later long-term risk of cardiometabolic complications appeared attributable to a general liability toward psychopathology. Sibling analyses suggested that the elevated risk could not be attributed to confounds shared within families, and the associations could be partly mediated via lifestyle factors. Clinicians may consider lifestyle-based interventions to reduce the risk of cardiometabolic complications for patients with several mental disorders. In study III, we investigated the link between chronic pain comorbidity and later suicidal behaviors. Based on nine self-reported chronic pain conditions, we identified three factors related to pain: one general pain factor, and two specific factors, which measure neck-shoulder pain and pain-related somatic symptoms respectively. And we applied a co-twin control model to control for familial confounding when regressing general and specific pain on suicidal behaviors. We found that general pain factor and somatic pain factor are associated with increased risk for suicidal behavior; but these associations appear to be mainly attributable to familial confounding. Clinicians may find it advantageous to assess pain comorbidity in addition to specific pain types. Nonetheless, addressing pain may not necessarily lead to a reduction in future suicidal tendencies, as the associations may be influenced by familial factors