Curves of Placental Weights of Live-Born Twins

The purpose of this study is to present curves of estimated placental growth in twins and to evaluate the relative contribution of gestational age, zygosity, chorionicity, fusion of the placentas, sex of the individual and of the twin pair, site of the umbilical cord insertion, birth order, maternal age, and parity. Perinatal data and placental data were obtained from 6315 live-born twin pairs from the East Flanders Prospective Twin Survey. Of 4318 twin pairs, with no missing values, the placental weights of different gestational ages were analyzed using a nonlinear multivariate Gaussian regression. Two groups were distinguished: (1) twins with two separate placentas, and (2) twins with only one placental mass (one placenta in case of monochorionic twins or two fused placentas in case of dichorionic placentas). Overall, placental weight was influenced by gestational age, fusion of the placentas, and parity. In the case of one placental mass, monozygotic dichorionic twins had the lowest weights. If two separate placentas were present, birth order played a role in favor of the first-born twin. For parity and zygosity, the differences were most pronounced between 27 and 29 weeks, whereas the difference for birth order was most pronounced between 33 and 37 weeks. In conclusion, basic physiological characteristics, routinely examined at birth, influence placental weight. Taking these covariates into account allows a better evaluation of the placental weight given a gestational age, as an indicator of growth

Lower emotional complexity as a prospective predictor of psychopathology in adolescents from the general population

Emotional complexity (EC) involves the ability to distinguish between distinct emotions (differentiation) and the experience of a large range of emotions (diversity). Lower EC has been related to psychopathology in cross-sectional studies. This study aimed to investigate (a) whether EC prospectively predicts psychopathology and (b) whether this effect is contingent on stressful life events. To further explore EC, we compared the effects of differentiation and diversity. Adolescents from the general population (N = 401) rated 8 negatively valenced emotions 10 times a day for 6 consecutive days. Further, they completed the Symptom Checklist-90 (baseline and 1-year follow-up) and a questionnaire on past year's life events at follow-up. Logistic regression analyses tested whether EC-reflected by emotion differentiation (intraclass correlation coefficient [ICC]) and diversity (diversity index [DI])-predicted prognosis (good: remitting or lacking symptoms vs. bad: worsening or persisting symptoms). EC predicted prognoses but only when based on the ICC (OREC.ICC = 1.42, p = .02). An ECICC 1 SD above average increased the probability of good prognosis from .67 to .74. This effect was not related to stressful life events (OREC × Life events = 1.03, p = .86) and disappeared when emotion intensity (mean level) was taken into account (OREC = 1.20, p = .20). Predicting future prognosis does not necessitate complex measures of emotional experience (ICC, DI) but rather might be achieved through simpler indices (mean). The discrepant effects of the ICC and DI on prognosis suggest that impaired emotion representation (ICC) plays a more important role in vulnerability to mental ill health than does low diversity of emotions (DI)

Early warning signals in psychopathology:what do they tell?

BACKGROUND: Despite the increasing understanding of factors that might underlie psychiatric disorders, prospectively detecting shifts from a healthy towards a symptomatic state has remained unattainable. A complex systems perspective on psychopathology implies that such symptom shifts may be foreseen by generic indicators of instability, or early warning signals (EWS). EWS include, for instance, increasing variability, covariance, and autocorrelation in momentary affective states-of which the latter was studied. The present study investigated if EWS predict (i) future worsening of symptoms as well as (ii) the type of symptoms that will develop, meaning that the association between EWS and future symptom shifts would be most pronounced for congruent affective states and psychopathological domains (e.g., feeling down and depression). METHODS: A registered general population cohort of adolescents (mean age 18 years, 36% male) provided ten daily ratings of their affective states for 6 consecutive days. The resulting time series were used to compute EWS in feeling down, listless, anxious, not relaxed, insecure, suspicious, and unwell. At baseline and 1-year follow-up, symptom severity was assessed by the Symptom Checklist-90 (SCL-90). We selected four subsamples of participants who reported an increase in one of the following SCL-90 domains: depression (N = 180), anxiety (N = 192), interpersonal sensitivity (N = 184), or somatic complaints (N = 166). RESULTS: Multilevel models showed that EWS in feeling suspicious anticipated increases in interpersonal sensitivity, as hypothesized. EWS were absent for other domains. While the association between EWS and symptom increases was restricted to the interpersonal sensitivity domain, post hoc analyses showed that symptom severity at baseline was related to heightened autocorrelations in congruent affective states for interpersonal sensitivity, depression, and anxiety. This pattern replicated in a second, independent dataset. CONCLUSIONS: The presence of EWS prior to symptom shifts may depend on the dynamics of the psychopathological domain under consideration: for depression, EWS may manifest only several weeks prior to a shift, while for interpersonal sensitivity, EWS may already occur 1 year in advance. Intensive longitudinal designs where EWS and symptoms are assessed in real-time are required in order to determine at what timescale and for what type of domain EWS are most informative of future psychopathology

Genetic, Maternal and Placental Factors in the Association between Birth Weight and Physical Fitness: A Longitudinal Twin Study

Background Adult cardiorespiratory fitness and muscle strength are related to all-cause and cardiovascular mortality. Both are possibly related to birth weight, but it is unclear what the importance is of genetic, maternal and placental factors in these associations. Design Peak oxygen uptake and measures of strength, flexibility and balance were obtained yearly during adolescence (10–18 years) in 114 twin pairs in the Leuven Longitudinal Twin Study. Their birth weights had been collected prospectively within the East Flanders Prospective Twin Survey. Results We identified linear associations between birth weight and adolescent vertical jump (b = 1.96 cm per kg birth weight, P = 0.02), arm pull (b = 1.85 kg per kg birth weight P = 0.03) and flamingo balance (b = −1.82 attempts to stand one minute per kg birth weight, P = 0.03). Maximum oxygen uptake appeared to have a U-shaped association with birth weight (the smallest and largest children had the lowest uptake, P = 0.01), but this association was no longer significant after adjustment for parental BMI. Using the individual twin’s deviation from his own twin pair’s average birth weight, we found positive associations between birth weight and adolescent vertical jump (b = 3.49, P = 0.0007) and arm pull (b = 3.44, P = 0.02). Δ scores were calculated within the twin pairs as first born twin minus second born twin. Δ birth weight was associated with Δ vertical jump within MZ twin pairs only (b = 2.63, P = 0.009), which indicates importance of placental factors. Conclusions We found evidence for an association between adolescent physical performance (strength, balance and possibly peak oxygen uptake) and birth weight. The associations with vertical jump and arm pull were likely based on individual, more specifically placental (in the case of vertical jump) factors. Our results should be viewed as hypothesis-generating and need confirmation, but potentially support preventive strategies to optimize birth weight, for example via placental function, to target later fitness and health

Critical slowing down as early warning for the onset and termination of depression

About 17% of humanity goes through an episode of major depression at some point in their lifetime. Despite the enormous societal costs of this incapacitating disorder, it is largely unknown how the likelihood of falling into a depressive episode can be assessed. Here, we show for a large group of healthy individuals and patients that the probability of an upcoming shift between a depressed and a normal state is related to elevated temporal autocorrelation, variance, and correlation between emotions in fluctuations of autorecorded emotions. These are indicators of the general phenomenon of critical slowing down, which is expected to occur when a system approaches a tipping point. Our results support the hypothesis that mood may have alternative stable states separated by tipping points, and suggest an approach for assessing the likelihood of transitions into and out of depression

FADS2 Genetic Variance in Combination with Fatty Acid Intake Might Alter Composition of the Fatty Acids in Brain

Multiple lines of evidence suggest that fatty acids (FA) play an important role in cognitive function. However, little is known about the functional genetic pathways involved in cognition. The main goals of this study were to replicate previously reported interaction effects between breast feeding (BF) and FA desaturase (FADS) genetic variation on IQ and to investigate the possible mechanisms by which these variants might moderate BF effect, focusing on brain expression. Using a sample of 534 twins, we observed a trend in the moderation of BF effects on IQ by FADS2 variation. In addition, we made use of publicly available gene expression databases from both humans (193) and mice (93) and showed that FADS2 variants also correlate with FADS1 brain expression (P-value<1.1E-03). Our results provide novel clues for the understanding of the genetic mechanisms regulating FA brain expression and improve the current knowledge of the FADS moderation effect on cognition

Association between birth weight and educational attainment : an individual-based pooled analysis of nine twin cohorts

Background There is evidence that birth weight is positively associated with education, but it remains unclear whether this association is explained by familial environmental factors, genetic factors or the intrauterine environment. We analysed the association between birth weight and educational years within twin pairs, which controls for genetic factors and the environment shared between co-twins. Methods The data were derived from nine twin cohorts in eight countries including 6116 complete twin pairs. The association between birth weight and educational attainment was analysed both between individuals and within pairs using linear regression analyses. Results In between-individual analyses, birth weight was not associated with educational years. Within-pairs analyses revealed positive but modest associations for some sex, zygosity and birth year groups. The greatest association was found in dizygotic (DZ) men (0.65 educational years/kg birth weight, p=0.006); smaller effects of 0.3 educational years/kg birth weight were found within monozygotic (MZ) twins of both sexes and opposite-sex DZ twins. The magnitude of the associations differed by birth year in MZ women and opposite-sex DZ twins, showing a positive association in the 1915-1959 birth cohort but no association in the 1960-1984 birth cohort. Conclusion Although associations are weak and somewhat inconsistent, our results suggest that intrauterine environment may play a role when explaining the association between birth weight and educational attainment.Peer reviewe

Familial Resemblance for Loneliness

Social isolation and loneliness in humans have been associated with physical and psychological morbidity, as well as mortality. This study aimed to assess the etiology of individual differences in feelings of loneliness. The genetic architecture of loneliness was explored in an extended twin-family design including 8,683 twins, siblings and parents from 3,911 families. In addition, 917 spouses of twins participated. The presence of assortative mating, genetic non-additivity, vertical cultural transmission, genotype–environment (GE) correlation and interaction was modeled. GE interaction was considered for several demographic characteristics. Results showed non-random mating for loneliness. We confirmed that loneliness is moderately heritable, with a significant contribution of non-additive genetic variation. There were no effects of vertical cultural transmission. With respect to demographic characteristics, results indicated that marriage, having offspring, more years of education, and a higher number of siblings are associated with lower levels of loneliness. Interestingly, these effects tended to be stronger for men than women. There was little evidence of changes in genetic architecture as a function of these characteristics. We conclude that the genetic architecture of loneliness points to non-additive genetic influences, suggesting it may be a trait that was not neutral to selection in our evolutionary past. Sociodemographic factors that influence the prevalence of loneliness do not affect its genetic architecture