Genetic and environmental relationships between head circumference growth in the first year of life and sociocognitive development in the second year: a longitudinal twin study

Although growth in head circumference (HC) during infancy is known to predict later childhood outcomes, the mechanisms underlying this association with later sociocognitive abilities remain undetermined. Thus, using a sample of 241 pairs of normally developing Japanese twins, this study investigated the underpinnings of the association between HC growth (difference between HC at birth and at 10 months) and sociocognitive abilities at 19 months as measured by 10 items from the M-CHAT. Phenotypic correlations between HC at birth and sociocognitive abilities and between HC growth and sociocognitive abilities were marginal and not significant. However, multivariate genetic analyses using Cholesky decomposition revealed that genetic influences on HC growth and those on sociocognitive abilities were negatively associated. On the other hand, shared and nonshared environmental influences on HC growth were positively associated with influences on sociocognitive abilities. Genetic and environmental influences on HC at birth were not significantly associated with influences on sociocognitive abilities. These results help to clarify the role of brain growth during infancy in the subsequent development of sociocognitive abilities and highlight the importance of examining the different roles of genetic and environmental influences in studies of these areas.     

Conflict of Interest and the CREATE-X Trial in the New England Journal of Medicine

There is an increasing emphasis on clear disclosure of conflict of interest in medical communities, following repeated scientific frauds in clinical trials. However, incomplete COI statements continue to be prevalent in the medical community, as appears to have occurred in the Capecitabine for Residual Cancer as Adjuvant Therapy (CREATE-X) trial, which was recently published in the New England Journal of Medicine. The authors of the article did not clearly report the roles of the Japan Breast Cancer Research Group, a sponsor and funder of the study, although a majority of the Japanese authors served in important positions in the organization. Furthermore, the conflict of interest related to Chugai Pharmaceutical Company, a Japanese distributor of capecitabine, was not correctly disclosed. More transparent statements of conflict of interest and clarification of sponsors and funders’ roles, as well as rigorous review by academic journals are required to fairly interpret the findings of clinical trials, including and beyond the single case of the CREATE-X trial.     

Long-lasting effects of inescapable-predator stress on brain tryptophan metabolism and the behavior of juvenile mice

The kynurenine (KYN) pathway, which is initiated by indoleamine 2,3-dioxygenase, is the main tryptophan (TRP) metabolic pathway. It shares TRP with the serotonin (5-HT) pathway. We investigated the influence of inescapable-predator (rat) stress on behavior and brain TRP metabolism in mice. Male ICR mice (4W) were exposed to 20-min inescapable-predator stress. Behavior on an elevated plus-maze, and TRP, KYN, and 5-HT levels in the prefrontal cortex, hippocampus, amygdala, and dorsal raphe nuclei were measured 1 and 4 weeks after stress exposure. Predator stress increased the number of open-arm entries (NOA) 4 weeks after stress exposure without altering the number of closed-arm entries (NCA). Thus, the open/closed-arm entry ratio (NOA/NCA) increased after stress exposure. Predator stress increased KYN levels in the prefrontal cortex (until 4 weeks after stress exposure) and dorsal raphe nuclei (for 1 week after stress exposure), decreased 5-HT levels in all brain regions (until 4 weeks after stress exposure). Thus, predator stress increased the KYN/5-HT ratio in all regions, in particular in the prefrontal cortex and hippocampus until 4 weeks after stress exposure. Predator stress shifted the balance between the KYN and 5-HT pathways to the KYN pathway, and induced behavioral disinhibition.     

Is g an entity? A Japanese twin study using syllogisms and intelligence tests

Using a behavioral genetic approach, we examined the validity of the hypothesis concerning the singularity of human general intelligence, the g theory, by analyzing data from two tests: the first consisted of 100 syllogism problems and the second a full-scale intelligence test. The participants were 448 Japanese young adult twins (167 pairs of identical and 53 pairs of fraternal twins). Data were analyzed for their fit to two kinds of multivariate genetic models: a common pathway model, in which a higher-order latent variable, g, was postulated as an entity; and an independent pathway model, in which the higher-order latent variable was not posited. These analyses revealed that the common pathway model which included additive genetic and nonshared environmental factors best accounted for the three distinct mental abilities: syllogistic logical deductive reasoning, verbal, and spatial. Both the substantial g-loading for syllogism-solving, historically recognized as the symbol of human intelligence, and the emergence of g as an entity at an etiological level, that is, at the genetic and environmental factor level, provide further support for the g theory.     

Curiosity about a positive or negative event prolongs the duration of emotional experience

Some researchers claim that uncertainty prolongs the duration of emotional experiences because uncertainty toward an emotion-eliciting event prolongs attention to that event. However, some results contradict this claim. We assumed that curiosity rather than uncertainty prolongs the duration of emotional experience via attention, and that attention and emotional experience are prolonged only when uncertainty elicits curiosity. This assumption is based on the information gap theory, which proposes that curiosity increases with uncertainty, but that curiosity decreases at a certain level of uncertainty. We conducted a survey study to investigate the relationships among curiosity, uncertainty, attention and duration of positive and negative emotional experiences. The results showed that curiosity, but not uncertainty, prolonged the duration of emotional experiences and the process was completely mediated by attention both for positive and negative emotions. Moreover, uncertainty prolonged the duration of emotional experiences only when uncertainty elicited curiosity, which in turn prolonged attention to the emotion-eliciting event.     

Hyperactivity/inattention problems moderate environmental but not genetic mediation between negative parenting and conduct problems

This study investigated the association between negative parenting (NP) and conduct problems (CP) in 6-year-old twins, taking into account the severity of hyperactivity/inattention problems (HIAP). Analyses of the data from 1,677 pairs of twins and their parents revealed that the shared environmental covariance between NP and CP was moderated by the level of HIAP but not by CP or NP, where the shared environmental covariance was larger in children with higher levels of HIAP than in children with lower levels of HIAP. The genetic covariance between NP and CP was not moderated by the level of HIAP, whereas it was larger in the group with lower levels of CP and NP than in the group with higher levels. These results suggest that severe HIAP strengthens shared environmental associations between NP and CP and that interventions focusing on the shared environmental component of NP would be effective for parents and children with severe HIAP.     

Changes in brain tryptophan metabolism elicited by ageing, social environment, and psychological stress in mice

The kynurenine (KYN) pathway, which is initiated by indoleamine 2,3-dioxygenase (IDO), is a tryptophan (TRP) metabolic pathway. It shares TRP with the serotonin (5-hydroxytryptamine, 5-HT) pathway. In major depression, activation of the KYN pathway may deplete 5-HT. In the present study we investigated the influence of various risk factors for depression, such as ageing, social isolation and psychological stress, on TRP metabolism. Male ICR mice (postnatal day, PND, 21) were divided into two housing conditions, isolation and group housing, reared for 4 weeks (young adult) or 5 months (adult) and exposed to novelty stress. We measured TRP, KYN and 5-HT contents in the prefrontal cortex, hippocampus, amygdala and dorsal raphe nuclei to investigate the balance between the KYN and 5-HT pathways. Ageing decreased TRP and KYN and increased 5-HT. Thus, ageing shifted the balance to the latter. In the younger group, social isolation decreased TRP and KYN and increased the 5-HT/TRP ratio, whereas novelty stress increased TRP and KYN and decreased the 5-HT/TRP ratio. Thus, social isolation shifted the balance to the latter, whereas novelty stress shifted it to the former. In the older group, these effects were restricted to specific brain regions. Ageing and social isolation counteracted novelty stress effects on TRP metabolism.     

Counteractive control over temptations: Promoting resistance through enhanced perception of conflict and goal value

The present research explored people’s everyday practice of counteractive control. Experience sampling was used to test our prediction that strong temptations would promote self-control. Participants were 237 Japanese citizens with ages ranging from 18 to 69. Results indicated that perceived temptation prompted stronger resistance and restraint of behaviors, compared to those cases where no conflict was perceived. In addition, multilevel path analysis revealed the underlying process such that (a) a strong desire toward temptation intensified perception of conflict; (b) perceived conflict bolstered the value of goals that were in disagreement with the temptation; and (c) highly valued goals promoted self-control (i.e., stronger resistance and hence less yielding to temptation).     

Independent Female Escort’s Strategies for Coping with Sex Work Related Stigma

Despite the reframing of ??prostitution?? as ??sex work?? in research and advocacy literature, the stigma associated with this activity persists. This study examines how independent female sex workers advertising online as ??escorts?? perceive and manage the stigma associated with their work, and how these coping strategies impact their personal relationships. Thirty escorts participated in semi-structured qualitative interviews; Goffman??s (1963) theory of stigma and information management strategies was used as a theoretical framework to guide the analysis of women??s experiences. Women who engaged in selective disclosure regarding sex work reported greater access to social support, while women who concealed their work from most people often reported feeling lonely and socially isolated. Escorts?? stigma coping strategies may have significant impact on their social relationships and access to social support.