The effects of parental presence on amygdala and mPFC activation during fear conditioning: An exploratory study

Learning safe versus dangerous cues is crucial for survival. During development, parents can influence fear learning by buffering their children's stress response and increasing exploration of potentially aversive stimuli. Rodent findings suggest that these behavioral effects are mediated through parental presence modulation of the amygdala and medial prefrontal cortex (mPFC). Here, we investigated whether similar parental modulation of amygdala and mPFC during fear learning occurs in humans. Using a within-subjects design, behavioral (final N = 48, 6-17 years, mean = 11.61, SD = 2.84, 60% females/40% males) and neuroimaging data (final N = 39, 6-17 years, mean = 12.03, SD = 2.98, 59% females/41% males) were acquired during a classical fear conditioning task, which included a CS+ followed by an aversive noise (US; 75% reinforcement rate) and a CS-. Conditioning occurred once in physical contact with the participant's parent and once alone (order counterbalanced). Region of interest analyses examined the unconditioned stress response by BOLD activation to the US (vs. implicit baseline) and learning by activation to the CS+ (vs. CS-). Results showed that during US presentation, parental presence reduced the centromedial amygdala activity, suggesting buffering of the unconditioned stress response. In response to learned stimuli, parental presence reduced mPFC activity to the CS+ (relative to the CS-), although this result did not survive multiple comparisons' correction. These preliminary findings indicate that parents modulate amygdala and mPFC activity during exposure to unconditioned and conditioned fear stimuli, potentially providing insight into the neural mechanisms by which parents act as a social buffer during fear learning. RESEARCH HIGHLIGHTS: (1)This study used a within-participant experimental design to investigate how parental presence (vs. absence) affects youth's neural responses in a classical fear conditioning task. (2)Parental presence reduced the youth's centromedial amygdala activation to the unconditioned stimulus (US), suggesting parental buffering of the neural unconditioned response (UR). (3)Parental presence reduced the youth's mPFC activation to a conditioned threat cue (CS+) compared to a safety cue (CS-), suggesting possible parental modulation of fear learning.

The relationship between empathy and executive functions among young adolescents

Empathy and executive functions (EFs) are multimodal constructs that enable individuals to cope with their environment. Both abilities develop throughout childhood and are known to contribute to social behavior and academic performance in young adolescents. Notably, mentalizing and EF activate shared frontotemporal brain areas, which in previous studies of adults led researchers to suggest that at least some aspects of empathy depend on intact EF mechanisms. Despite the substantial development that empathy and EF undergo during adolescence, no study to date has systematically examined the associations between components of empathy and EF in this age group. Here, we explore these associations using data from an online battery of tasks, collected as part of a longitudinal twin study (N = 593; Mage 11.09 ± 0.2; 53.46% female, Israeli adolescents from Jewish decent). Using a confirmatory factor analysis, we quantified the associations between the main components of empathy (mentalizing and interpersonal concern) and of EF (working memory [WM], inhibition and shifting [IaS]). We found that WM was related to both mentalizing and interpersonal concern, whereas IaS were related to mentalizing but not to interpersonal concern. We also discuss the genetic and environmental contributions to individual differences in each factor. Our findings show both similarities and differences from previous findings in adults, suggesting that the ongoing brain maturation processes and environmental age-dependent experiences in adolescence may affect the developing relation between cognitive and emotional development. These results have implications for better understanding and treating clinical populations demonstrating executive or emotional deficits, specifically during adolescence. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Food-specific IgA levels in esophageal biopsies are not sufficiently high to predict food triggers in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is an immune-mediated disease, characterized by Th2-type inflammation linked to specific foods. No currently available allergy tests reliably identify food triggers in EoE, leading to empiric dietary elimination strategies. Recently, milk- and wheat-specific IgA in esophageal brushings were linked to clinical food triggers. In this study, we aimed to determine whether food-specific IgA from esophageal biopsies is associated with known food triggers.

METHODS

A prior cohort of 21 patients (median age 39 years) with confirmed EoE underwent empirical elimination diets and subsequent reintroduction of foods to determine triggers. Archived baseline biopsies were used to quantify levels of peanut-, milk-, soy-, egg-, wheat-specific and total IgA by enzyme-linked immunosorbent assay.

RESULTS

Overall, 13 patients (62%) responded to the dietary elimination as determined by histology (<15 eos/hpf), with milk and egg being the most common triggers. Biopsies had varying amounts of total IgA, while food-specific IgA was only detectable in 48 of 105 (46%) samples. Food-specific IgA was normalized to total IgA for each sample and stratified by whether a food was a known trigger. For all foods tested, there were no significant differences in IgA between positive and negative triggers.

CONCLUSIONS

Food-specific IgA in esophageal biopsies was not associated with previously identified food triggers in this cohort. Future studies comparing food-specific IgA in esophageal brushings, mucous scrapings, and biopsies from patients with known triggers will be critical to determining whether food-specific IgA may serve as a biomarker for identification of EoE triggers.

Same Day Infusion of Iron Therapy Is Associated With No Increased Risk for Adverse Events Among Patients Receiving Biological Infusions for Inflammatory Bowel Disease

GOALS

The goal of this study was to compare the relative safety of administering iron infusions on the same day as intravenous (IV) biological therapy to the administration of these treatments on different days in patients with inflammatory bowel disease (IBD).

BACKGROUND

IV iron therapy is often required in patients with IBD. Many patients with IBD who receive IV iron therapy in the outpatient setting also receive biological infusion therapy for treatment of their IBD.

STUDY

Patients with IBD who received IV iron therapy at a single infusion center were included. We compared documented infusion-related reactions in patients with patients receiving an iron infusion on the same day as their biological infusion to those who received their iron infusion on a different day.

RESULTS

Among 481 patients, 129 received an iron infusion on the same day as a biologic infusion. There was no significant difference in the incidence of infusion reaction when comparing patients who received biological infusion therapy in the same session as the iron infusion to those patients who received a biological infusion on a different day (5% vs. 7%, P =0.246) or any IBD-related therapy (5% vs. 8%, P =0.206).

CONCLUSIONS

The frequency and type of infusion reactions in patients receiving IV iron therapy on the same day after IV therapy with biologics was not increased compared with patients who received a biological infusion on a different day. A sequential infusion of biological therapy followed by IV iron therapy may be a safe and cost-effective approach.

Personal Values and Sustained Attention as Predictors of Children's Helping Behavior in Middle Childhood

OBJECTIVE

This study tested the effect of personal values (motivation) and sustained attention (cognitive ability) on children's helping behavior.

METHOD

Children (N = 162, age range 8-9 years, mean = 8.81, SD =.43) completed value ranking and go/no-go tasks, and their helping behavior was examined.

RESULTS

Children who valued self-transcendence over self-enhancement helped more than others. Surprisingly, children's lack of sustained attention was associated with more helping among those who valued self-transcendence over self-enhancement or openness-to-change over conservation values. Valuing both self-transcendence and openness-to-change was also associated with more helping.

CONCLUSIONS

Children are more likely to help others if they value self-transcendence and openness to change. Notably, children's tendency to act upon these values may be facilitated (rather than obstructed by) low attention skills.

The empathic personality profile: Using personality characteristics to reveal genetic, environmental, and developmental patterns of adolescents' empathy

How do genetic and environmental processes affect empathy during early adolescence? This study illumined this question by examining the etiology of empathy with the etiology of other personality characteristics. Israeli twin adolescents rated their empathy and personality at ages 11 (N=1176) and 13 (N=821) (733 families, 51.4% females). Parents rated adolescents' emotional empathy. Adolescents performed an emotion recognition task, indicating cognitive empathy. Using a cross-validated statistical learning algorithm, this study found emotional and cognitive 'empathic personality profiles', which describe and predict self-reported empathy from nuanced Big-Five personality characteristics, or 'nuances' (i.e., individual items). These profiles predicted empathy moderately (R² =.17-.24) and were stable and robust, within each age and between ages. They also predicted empathy in a new sample of older non-twin adolescents (N=96) and were validated against non-self-report empathy measures. Both emotional and cognitive empathy were predicted by nuances representing positive attitudes toward others, trust, forgiveness, and openness to experiences. Emotional empathy was also predicted by nuances representing anxiousness and negative reactivity. Twin analyses revealed overlapping genetic and environmental influences on empathy and the empathic personality profiles and overlapping environmental influences on empathy-personality change. This study demonstrates how addressing the complexity of individuals' personalities can inform adolescents' empathy development.

Changing genetic architecture of body mass index from infancy to early adulthood: an individual based pooled analysis of 25 twin cohorts

Background

Body mass index (BMI) shows strong continuity over childhood and adolescence and high childhood BMI is the strongest predictor of adult obesity. Genetic factors strongly contribute to this continuity, but it is still poorly known how their contribution changes over childhood and adolescence. Thus, we used the genetic twin design to estimate the genetic correlations of BMI from infancy to adulthood and compared them to the genetic correlations of height.

Methods

We pooled individual level data from 25 longitudinal twin cohorts including 38,530 complete twin pairs and having 283,766 longitudinal height and weight measures. The data were analyzed using Cholesky decomposition offering genetic and environmental correlations of BMI and height between all age combinations from 1 to 19 years of age.

Results

The genetic correlations of BMI and height were stronger than the trait correlations. For BMI, we found that genetic correlations decreased as the age between the assessments increased, a trend that was especially visible from early to middle childhood. In contrast, for height, the genetic correlations were strong between all ages. Age-to-age correlations between environmental factors shared by co-twins were found for BMI in early childhood but disappeared altogether by middle childhood. For height, shared environmental correlations persisted from infancy to adulthood.

Conclusions

Our results suggest that the genes affecting BMI change over childhood and adolescence leading to decreasing age-to-age genetic correlations. This change is especially visible from early to middle childhood indicating that new genetic factors start to affect BMI in middle childhood. Identifying mediating pathways of these genetic factors can open possibilities for interventions, especially for those children with high genetic predisposition to adult obesity.

Association of eosinophilic esophagitis with autoimmune and connective tissue disorders, and the impact on treatment response

Eosinophilic esophagitis (EoE) has been associated with autoimmune (AI) and connective tissue disorders (CTDs), but clinical correlates and treatment response to topical corticosteroids (tCS) for patients with both conditions are not well known. We aimed to determine the prevalence and clinical features of AI/CTDs in EoE patients, and assess the response to tCS. In this retrospective cohort study of adults and children newly diagnosed with EoE in the University of North Carolina EoE Clinicopathologic database, we extracted clinical characteristics and treatment response data. We compared EoE patients with and without AI/CTDs, identified independently associated factors, and explored treatment responses. Of 1029 EoE patients, 61 (5.9%) had an AI/CTDs. The most common AI/CTDs were psoriasis/psoriatic arthritis (P/PA) (1.7%), Hashimoto's (1.2%), and rheumatoid arthritis (RA) (1%). Compared to those without AI/CTDs, AI/CTDs patients were older (35 vs. 28 years, P = 0.004), more likely to be female (51% vs. 30%, P = 0.001), have insurance (93% vs. 78%, P = 0.004) and a longer symptom duration prior to EoE diagnosis (10 vs. 7 years, P = 0.02). Older age, female sex, having insurance, and having allergic rhinitis were independently associated with AI/CTDs. AI/CTD patients with EoE were less likely to have a symptom response (47% vs. 79%, P = 0.003). Overlap between EoE and AI/CTDs was uncommon, seen in approximately 6%, with P/PA, Hashimoto's, and RA being most frequent. In conclusion, older age, female sex, having insurance, and allergic rhinitis were independently associated with AI/CTDs. EoE patients with AI/CTDs had less symptom response, with trendtowards lower endoscopic and histologic responses, to tCS therapy.

The genetic and environmental origins of emotional and cognitive empathy: Review and meta-analyses of twin studies

Empathy is considered a cornerstone of human social experience, and as such has been widely investigated from psychological and neuroscientific approaches. To better understand the factors influencing individual differences in empathy, we reviewed and meta-analyzed the behavioral genetic literature of emotional empathy- sharing others' emotions (k=13), and cognitive empathy- understanding others' emotions (k = 15), as manifested in twin studies. Results showed that emotional empathy is more heritable, 48.3 % [41.3 %-50.6 %], than cognitive empathy, 26.9 % [18.1 %-35.8 %]. Moreover, cognitive empathy as examined by performance tests was affected by the environment shared by family members, 11.9 % [2.6 %-21.0 %], suggesting that emotional understanding is influenced, to some degree, by environmental factors that have similar effects on family members beyond their genetic relatedness. The effects of participants' age and the method used to asses empathy on the etiology of empathy were also examined. These findings have implications for understanding how individual differences in empathy are formed. After discussing these implications, we suggest theoretical and methodological future research directions that could potentially elucidate the relations between genes, brain, and empathy.

Social interaction context shapes emotion recognition through body language, not facial expressions

The social context-seeing people emotionally interacting-is one of the most common contexts in which emotion perception occurs. Despite its importance, emotion perception of social interactions from a 3rd-person perspective is poorly understood. Here we investigated whether emotion recognition of fear and anger is facilitated by mere congruency (the contextual figure exhibits the same emotion as the target) or by functional relations (the contextual figure exhibits a complementary emotion to the target). Furthermore, we examined which expression channel, face or body, drives social context effects. In the 1st 2 experiments (Studies 1a and 1b), participants in an online survey platform (N = 146) or university students (N = 34), viewed interacting figures displaying fear or anger, presented either as faces, bodies, or both. Participants were instructed to categorize the target figure's emotions while the other figure served as context. Results showed that fear recognition was facilitated by an interacting angry figure more strongly than by an interacting fearful figure. Moreover, this effect occurred when participants viewed the figures' bodies (with or without the faces), but not when they viewed the figures' faces alone. A 3rd online experiment (Study 2) established that this context effect was stronger when participants (N = 464) watched the figures interacting (facing each other) than when figures were not interacting (facing away from each other), suggesting that social context influences emotion perception by revealing the interactants' relation. Our findings demonstrate that emotional perception is grounded in the broader process of social interaction and highlight the role of the body in interpersonal context effects. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

A longitudinal genetically informed analysis of parental negativity and children's negative emotionality in middle childhood

Children's negative emotionality (NE) is frequently associated with parental negativity, but causal understanding of this relationship is limited. In addition, little is known about how genetic and environmental factors affect this relationship during middle childhood. We addressed these gaps by applying a quantitative genetic analysis to cross-lagged associations between mothers' and fathers' parental negativity and children's NE during middle childhood. The sample comprised of 456 families when the children were 6.5 years old, and 401 families when the children were 8/9 years old. Mothers' and fathers' negativity and children's NE were assessed using questionnaires. Results showed that variation in parental negativity was mainly accounted for by the environment shared by children, with some indication of an evocative effect of the children's genes on mothers, but not fathers. Children's NE was accounted for by both genetic and shared environmental influences. Parental negativity and children's NE had moderate continuity over the course of two years. Mothers' (but not fathers') negativity when the children were 6.5 years old predicted change in children's NE (rated by the same or the other parent) toward age 8/9 years, but not the other way around. Shared environmental influences were the main contributor to the association between earlier mothers' negativity and later children's NE. Thus, although children's NE was partially heritable, and parenting too was partially accounted for by children's genes, the association between parental negativity and children's NE, at this age, reflects environmental effects and is compatible with mothers' influence on children. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Genetic and environmental factors affecting birth size variation: a pooled individual-based analysis of secular trends and global geographical differences using 26 twin cohorts

Background

The genetic architecture of birth size may differ geographically and over time. We examined differences in the genetic and environmental contributions to birthweight, length and ponderal index (PI) across geographical-cultural regions (Europe, North America and Australia, and East Asia) and across birth cohorts, and how gestational age modifies these effects.

Methods

Data from 26 twin cohorts in 16 countries including 57 613 monozygotic and dizygotic twin pairs were pooled. Genetic and environmental variations of birth size were estimated using genetic structural equation modelling.

Results

The variance of birthweight and length was predominantly explained by shared environmental factors, whereas the variance of PI was explained both by shared and unique environmental factors. Genetic variance contributing to birth size was small. Adjusting for gestational age decreased the proportions of shared environmental variance and increased the propositions of unique environmental variance. Genetic variance was similar in the geographical-cultural regions, but shared environmental variance was smaller in East Asia than in Europe and North America and Australia. The total variance and shared environmental variance of birth length and PI were greater from the birth cohort 1990-99 onwards compared with the birth cohorts from 1970-79 to 1980-89.

Conclusions

The contribution of genetic factors to birth size is smaller than that of shared environmental factors, which is partly explained by gestational age. Shared environmental variances of birth length and PI were greater in the latest birth cohorts and differed also across geographical-cultural regions. Shared environmental factors are important when explaining differences in the variation of birth size globally and over time.

Parental Education and Genetics of BMI from Infancy to Old Age: A Pooled Analysis of 29 Twin Cohorts

OBJECTIVE

The objective of this study was to analyze how parental education modifies the genetic and environmental variances of BMI from infancy to old age in three geographic-cultural regions.

METHODS

A pooled sample of 29 cohorts including 143,499 twin individuals with information on parental education and BMI from age 1 to 79 years (299,201 BMI measures) was analyzed by genetic twin modeling.

RESULTS

Until 4 years of age, parental education was not consistently associated with BMI. Thereafter, higher parental education level was associated with lower BMI in males and females. Total and additive genetic variances of BMI were smaller in the offspring of highly educated parents than in those whose parents had low education levels. Especially in North American and Australian children, environmental factors shared by co-twins also contributed to the higher BMI variation in the low education level category. In Europe and East Asia, the associations of parental education with mean BMI and BMI variance were weaker than in North America and Australia.

CONCLUSIONS

Lower parental education level is associated with higher mean BMI and larger genetic variance of BMI after early childhood, especially in the obesogenic macro-environment. The interplay among genetic predisposition, childhood social environment, and macro-social context is important for socioeconomic differences in BMI.

From negative reactivity to empathic responding: Infants high in negative reactivity express more empathy later in development, with the help of regulation

Empathy has great effect on human well-being, promoting healthy relationships and social competence. Although it is increasingly acknowledged that infants show empathy toward others, individual differences in infants' empathy from the first year of life have rarely been investigated longitudinally. Here we examined how negative reactivity and regulation, two temperament traits that predict empathic responses in older children and adults, relate to infants' empathy. Infants were studied at the ages of nine (N = 275) and 18 (N = 301) months (194 infants were studied at both ages). Empathic responses were assessed by infants' observed reactions to an experimenter's simulated distress. Negative reactivity (fear, sadness, and distress to limitations) and regulation (soothability and effortful control) were assessed by parental reports. Negative reactivity was also examined by infants' observed reactions to an adult stranger (fear) and during interaction with their mothers (displays of sadness/distress). When examined cross-sectionally, infants' fear and distress to limitations associated with self-distress in response to others' distress. In contrast, when examined longitudinally, early sadness and distress to limitations, but not fear, associated with later empathic concern and inquisitiveness. Moreover, this longitudinal relation was moderated by infants' soothability and was evident only for children that had high soothability by the later time-point. Our findings suggest that infants who at an earlier age show negative reactivity, react later in development with more empathy if they achieve sufficient regulation abilities. By that, the findings stress the developmental nature of temperament-empathy relations during infancy.

Identity exploration and commitment in early adolescence: Genetic and environmental contributions

Identity formation is a key developmental task in adolescence. Although many adolescents in modern societies face issues of identity, there are substantial individual differences in identity exploration and commitment. Little is known about the origins of these individual differences. The current study investigated the genetic and environmental contributions to identity formation. In total, 571 11-year-old twins (85 monozygotic complete pairs and 176 dizygotic complete pairs) reported on their identity formation, using the Dimensions of Identity Development Scale (DIDS; Luyckx, Schwartz, Berzonsky, et al., 2008), as part of the Longitudinal Israeli Study of Twins (LIST; Avinun & Knafo, 2013). Multidimensional scaling analysis and confirmatory factor analysis supported the presence of all 5 dimensions at this young age: commitment making, exploration in-breadth, ruminative exploration, identification with commitment, and exploration in-depth. However, a model where exploration in-depth was divided into two subscales had a better fit to the data. Monozygotic twins were more similar to each other than dizygotic twins on all dimensions, except for one of the exploration in-depth subscales, supporting the idea that individual differences in various dimensions of identity formation are at least partially influenced by genetics (18-45%). For these dimensions, the rest of the variance was explained by nonshared environment effects (55-82%). Only one of the exploration in-depth subscales, that is, the tendency to explore commitments through discussion with others, showed evidence for the influence of the environment shared by twins (21%) but no genetic effect. Implications of the findings regarding the role of genetics and environment to identity formation are discussed. (PsycINFO Database Record

Associations between birth size and later height from infancy through adulthood: An individual based pooled analysis of 28 twin cohorts participating in the CODATwins project

BACKGROUND

There is evidence that birth size is positively associated with height in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment.

AIM

To analyze the associations of birth weight, length and ponderal index with height from infancy through adulthood within mono- and dizygotic twin pairs, which provides insights into the role of genetic and environmental individual-specific factors.

METHODS

This study is based on the data from 28 twin cohorts in 17 countries. The pooled data included 41,852 complete twin pairs (55% monozygotic and 45% same-sex dizygotic) with information on birth weight and a total of 112,409 paired height measurements at ages ranging from 1 to 69 years. Birth length was available for 19,881 complete twin pairs, with a total of 72,692 paired height measurements. The association between birth size and later height was analyzed at both the individual and within-pair level by linear regression analyses.

RESULTS

Within twin pairs, regression coefficients showed that a 1-kg increase in birth weight and a 1-cm increase in birth length were associated with 1.14-4.25 cm and 0.18-0.90 cm taller height, respectively. The magnitude of the associations was generally greater within dizygotic than within monozygotic twin pairs, and this difference between zygosities was more pronounced for birth length.

CONCLUSION

Both genetic and individual-specific environmental factors play a role in the association between birth size and later height from infancy to adulthood, with a larger role for genetics in the association with birth length than with birth weight.

Association between birthweight and later body mass index: an individual-based pooled analysis of 27 twin cohorts participating in the CODATwins project

Background

There is evidence that birthweight is positively associated with body mass index (BMI) in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment. We analysed the association between birthweight and BMI from infancy to adulthood within twin pairs, which provides insights into the role of genetic and environmental individual-specific factors.

Methods

This study is based on the data from 27 twin cohorts in 17 countries. The pooled data included 78 642 twin individuals (20 635 monozygotic and 18 686 same-sex dizygotic twin pairs) with information on birthweight and a total of 214 930 BMI measurements at ages ranging from 1 to 49 years. The association between birthweight and BMI was analysed at both the individual and within-pair levels using linear regression analyses.

Results

At the individual level, a 1-kg increase in birthweight was linearly associated with up to 0.9 kg/m2 higher BMI (P < 0.001). Within twin pairs, regression coefficients were generally greater (up to 1.2 kg/m2 per kg birthweight, P < 0.001) than those from the individual-level analyses. Intra-pair associations between birthweight and later BMI were similar in both zygosity groups and sexes and were lower in adulthood.

Conclusions

These findings indicate that environmental factors unique to each individual have an important role in the positive association between birthweight and later BMI, at least until young adulthood.

Genetic and environmental effects on body mass index from infancy to the onset of adulthood: an individual-based pooled analysis of 45 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) study

BACKGROUND

Both genetic and environmental factors are known to affect body mass index (BMI), but detailed understanding of how their effects differ during childhood and adolescence is lacking.

OBJECTIVES

We analyzed the genetic and environmental contributions to BMI variation from infancy to early adulthood and the ways they differ by sex and geographic regions representing high (North America and Australia), moderate (Europe), and low levels (East Asia) of obesogenic environments.

DESIGN

Data were available for 87,782 complete twin pairs from 0.5 to 19.5 y of age from 45 cohorts. Analyses were based on 383,092 BMI measurements. Variation in BMI was decomposed into genetic and environmental components through genetic structural equation modeling.

RESULTS

The variance of BMI increased from 5 y of age along with increasing mean BMI. The proportion of BMI variation explained by additive genetic factors was lowest at 4 y of age in boys (a(2) = 0.42) and girls (a(2) = 0.41) and then generally increased to 0.75 in both sexes at 19 y of age. This was because of a stronger influence of environmental factors shared by co-twins in midchildhood. After 15 y of age, the effect of shared environment was not observed. The sex-specific expression of genetic factors was seen in infancy but was most prominent at 13 y of age and older. The variance of BMI was highest in North America and Australia and lowest in East Asia, but the relative proportion of genetic variation to total variation remained roughly similar across different regions.

CONCLUSIONS

Environmental factors shared by co-twins affect BMI in childhood, but little evidence for their contribution was found in late adolescence. Our results suggest that genetic factors play a major role in the variation of BMI in adolescence among populations of different ethnicities exposed to different environmental factors related to obesity.

Genetic and environmental influences on height from infancy to early adulthood: An individual-based pooled analysis of 45 twin cohorts

Height variation is known to be determined by both genetic and environmental factors, but a systematic description of how their influences differ by sex, age and global regions is lacking. We conducted an individual-based pooled analysis of 45 twin cohorts from 20 countries, including 180,520 paired measurements at ages 1-19 years. The proportion of height variation explained by shared environmental factors was greatest in early childhood, but these effects remained present until early adulthood. Accordingly, the relative genetic contribution increased with age and was greatest in adolescence (up to 0.83 in boys and 0.76 in girls). Comparing geographic-cultural regions (Europe, North-America and Australia, and East-Asia), genetic variance was greatest in North-America and Australia and lowest in East-Asia, but the relative proportion of genetic variation was roughly similar across these regions. Our findings provide further insights into height variation during childhood and adolescence in populations representing different ethnicities and exposed to different environments.

Transkingdom control of microbiota diurnal oscillations promotes metabolic homeostasis

All domains of life feature diverse molecular clock machineries that synchronize physiological processes to diurnal environmental fluctuations. However, no mechanisms are known to cross-regulate prokaryotic and eukaryotic circadian rhythms in multikingdom ecosystems. Here, we show that the intestinal microbiota, in both mice and humans, exhibits diurnal oscillations that are influenced by feeding rhythms, leading to time-specific compositional and functional profiles over the course of a day. Ablation of host molecular clock components or induction of jet lag leads to aberrant microbiota diurnal fluctuations and dysbiosis, driven by impaired feeding rhythmicity. Consequently, jet-lag-induced dysbiosis in both mice and humans promotes glucose intolerance and obesity that are transferrable to germ-free mice upon fecal transplantation. Together, these findings provide evidence of coordinated metaorganism diurnal rhythmicity and offer a microbiome-dependent mechanism for common metabolic disturbances in humans with aberrant circadian rhythms, such as those documented in shift workers and frequent flyers.

Alexithymic characteristics and metabolic control in diabetic and healthy adults

Diabetes has long been identified as a disease with possible psychological components. Alexithymia--an inability to express emotions verbally, operational thinking, and a lack of fantasy life--is found in a high proportion of psychosomatic patients. We therefore tested the hypothesis that diabetics would be more alexithymic than controls. In addition, the lack of awareness of affect was hypothesized to have negative consequences for the management of diabetes, as reflected in metabolic glucose control (HbA1). The number of emotion words produced in six imaginative (Thematic Apperception Test) stories was used as the measure of alexithymia, with few words reflecting alexithymic characteristics. Diabetics were found to be significantly more alexithymic than controls. Further, fewer emotion words (alexithymia) was associated with poorer metabolic control. These data suggest that alexithymic characteristics may interfere with a diabetic's ability to manage their illness, and support previous research showing that the suppression of emotions can lead to a difficulty in regulating glucose levels.

Elevated sleep and waking heart rates in anxious depressions

Autonomic functioning, as measured by baseline heart rates during daytime (DHR) and during sleep (SLHR), was examined in 28 patients with major depressive disorder (MDD), 13 patients with panic disorder (PD), 28 patients with MDD and coexisting PD (MDD + PD), and 19 controls. DHR and SLHR in patients with PD or MDD did not differ from normals. Only the MDD + PD group showed significantly higher heart rates than controls. This pattern of results suggests a combined effect of MDD and PD, providing psychophysiological support for clinical findings of poorer prognosis in this group.