Correlation between gray/white matter volume and cognition in healthy elderly people

This study applied volumetric analysis and voxel-based morphometry (VBM) of brain magnetic resonance (MR) images to assess whether correlations exist between global and regional gray/white matter volume and the cognitive functions of semantic memory and short-term memory, which are relatively well preserved with aging, using MR image data from 109 community-dwelling healthy elderly individuals. We used the Information and Digit Span subtests of the Wechsler Adult Intelligent Scale-Revised as measures of semantic memory and short-term memory, respectively. We found significant positive correlations between the gray matter ratio, the percentage of gray matter volume in the intracranial volume, and performance on the Digit Span subtest, and between the regional gray matter volumes of the bilateral anterior temporal lobes and performance on the Information subtest. No significant correlations between performance on the cognitive tests and white matter volume were found. Our results suggest that individual variability in specific cognitive functions that are relatively well preserved with aging is accounted for by the variability of gray matter volume in healthy elderly subjects.     

Age differences in the effect of physical activity on depressive symptoms

This study examined associations between physical activity and depressive symptoms in 1,151 community-dwelling adults in Japan. Physical activity was measured using a pedometer, whereas depressive symptoms were assessed with the Center for Epidemiological Studies-Depression Scale. A structural equation modeling with a cross-lagged panel design revealed that for the older adults (65-79 years of age), daily walking at baseline predicted fewer depressive symptoms at the 2-year follow-up, even after adjusting for confounders. In contrast, the association was not confirmed for the middle-aged adults (40-64 years of age). Findings suggest that age should be considered when estimating the effect of physical activity on psychological well-being.     

Growth, population, and knowledge diffusion

This paper reviews the recent development of growth theory, focusing on the consistency between theory and evidence in terms of effects of population on growth, and presents some policy implications. Although positive effects of the population size on growth are likely to exist, the size does not necessarily mean the size of the domestic population. In the world with substantial but costly international knowledge diffusion, what affects growth is the population size of the technological leader country, the United States, from which knowledge spills over, and it is the world population when diffusion is costless. Therefore, policies to promote population growth may not be growth-enhancing for most advanced countries. A more effective population-related policy objective theoretically suggested is to encourage international knowledge diffusion. He may be reached at: yastodo@siu.edu. His current research interests include the process of knowledge diffusion among advanced countries as well as from advanced to developing countries.     

Genetic and Environmental Influences on the Development and Stability of Executive Functions in Children of Preschool Age: A Longitudinal Study of Japanese Twins

Executive functions (EF) are an important predictor of later adaptive development. A number of environmental influences, such as parenting, have been suggested as important promoters of EF development. However, behavioural genetic research has demonstrated that many environmental influences could be affected by genetic influences. Therefore, it is important to consider genetic variations when investigating environmental influences on EF development in children. To date, few studies have used genetically informative designs to assess the etiology of EF development during the preschool years, a period of rapid development. As a result, it remains unclear how and to what extent the environmental influences that are not confounded by genetic influences affect EF development during this developmental period. The present study explored EF development during the preschool years using a longitudinal and genetically informative design and a non‐Western population. Japanese twins were visited at their homes and individually tested on EF measures at 24, 36, and 48 months of age. Phenotypic correlations and confirmatory factor analyses suggested that EF are less cohesive at 24 months of age and emerge as a common single factor at 36 and 48 months. Additionally, longitudinal and multivariate behavioural genetic analyses indicated that the EF developmental change during this period is promoted by both shared and nonshared environmental influences as well as genetic influences, while EF stability is brought about by shared environments. The present findings elucidated the etiology of EF development during the preschool years and confirmed that this period is an important transitional stage for EF development. Copyright © 2016 John Wiley & Sons, Ltd.     

Mind perception of God in Japanese children

There is a theoretical debate regarding whether children represent God with reference to a human. Most previous studies have assessed this issue focusing on knowledge/omniscience in western children. This study used a theoretical framework characterising mental capacities in terms of motivational/emotional (experience) and cognitive (agency) mental capacities and tested whether Japanese children discriminated between God, a human, a baby and an invisible agent according to these capacities. Three‐ to 6‐year‐old children were asked about the experience and agency of the agents. The results revealed that children discriminated God from a human in terms of mental capacities including experience and agency in 3‐year‐old children. On the other hand, 4‐ to 6‐year‐old children, but not 3‐year‐old children, discriminated a human from a baby and an invisible person. The results suggest that the Japanese children's representations of God differed from their representation of a human during preschool years.     

Sex differences in the Schizotypal Personality Questionnaire Brief among Japanese employees and undergraduates: A cross-sectional study

Schizotypal personality may be seen as an indicator predisposition to schizophrenia and psychosis proneness. Schizotypal personality traits behave differently depending on a person’s age and sex, but few studies have examined the causal relationship between age-related sex differences and schizotypal personality traits. The aim of the present study was to examine the relationship between the schizotypal personality and sex in different age groups. In our study, we used the Schizotypal Personality Questionnaire Brief (SPQ-B). Participants were 371 college students (107 men) with an age range from 18 to 25 years, and 322 working people (156 men) with an age range of 22–67 years. The results showed that the young adult males in the college student group had tendencies to score higher than females in the same group on the SPQ-B total score and its two subscale scores (the cognitive-perceptual and the interpersonal scores). In the adult sample taken in the working people group, the total score and subscale scores of the SPQ-B did not significantly discriminate male subjects from female subjects. These findings indicate that sex differences of schizotypal personality traits may reflect differential age-related variation.     

Age,Emotion Regulation,and Affect in Adulthood: The Mediating Role of Cognitive Reappraisal

Evidence indicates that older adults experience high levels of emotional well‐being. However, little is known empirically about the underlying mechanism of this state. The purpose of the present study was to investigate whether emotion regulation mediates the link between age and affect in adulthood. The sample consisted of 516 Japanese participants aged 30 (±1), 50 (±1), and 70 (±1) years, who were registered with an Internet survey company. Cognitive reappraisal and expressive suppression were measured as emotion regulation strategies. Positive and negative affect were assessed. Older participants reported lower negative affect than younger participants, while positive affect was not correlated with age. Cognitive reappraisal partially mediated the relationship between age and affect, whereas expressive suppression did not. The results suggested that age‐related increase in cognitive reappraisal could contribute to improvements in affect, but that another adaptive form of emotion regulation may mediate the relationship between age and affect. Our study thus indicates that developments in emotion regulation could explain the mechanism of stable everyday affect throughout adulthood, and that researchers should further explore another form of adaptive emotion regulation.     

Prevalence of imaginary companions in Japanese children

Having an imaginary companion (IC) is an example of children's pretend play. However, most research regarding children's ICs is from Western cultures. In this study, the prevalence of ICs was assessed among Japanese children (2‐ to 9‐year‐old children, N = 800). The developmental (age), biological (sex), and environmental (birth order) effects on Japanese children's ICs were also assessed. Moreover, whether IC status can be an indicator of fantasy orientation in Japanese children was examined. The results revealed that the prevalence of the invisible friend was relatively rare, but the personified object was prevalent in Japanese children. Age and sex, but not birth order, significantly affected the prevalence of ICs in Japan. Moreover, IC status significantly indicated children's fantasy orientation. The results suggest that the characteristics of Japanese children's ICs are partly different from those in Western children. Social‐cultural contexts can affect this difference.     

The role of the prefrontal cortex in the go/no-go task in humans: a positron emission tomography study

To study the localization of response inhibition in the human brain, especially the role of the prefrontal cortex and laterality of its activation, we used positron emission tomography (PET) to measure regional cerebral blood flow in 11 right-handed participants while they performed a go/no-go and a simple control reaction-time task. In the control task, the participants responded to a target stimulus following a cue stimulus. In the go/no-go task they were instructed to inhibit the required response if the target stimulus did not appear. These tasks were performed using each hand. The right prefrontal cortex was found to be significantly activated when the go/no-go task was compared with the control task, regardless of the responding hand. The results indicated that response inhibition per se may be controlled by the right prefrontal cortex regardless of response hand for right-handed participants.     

Differences Between Australian and Japanese Students in Reported Use of Decision Processes

Decision making is an activity found in all cultures. Although many theoretical models have been developed to explain human decision making, very few have taken the role of culture into account. In this paper the importance of cultural influences on self-reported decision-making styles is examined, with particular emphasis on the dominant cultural pattern (i.e. “group orientation” versus “individual orientation”). Results of a questionnaire study of 743 Japanese and 309 Australian university students are presented. As predicted, Japanese students reported greater use of decision processes or behaviours associated with the involvement and influence of others (“collateral role”), while Australian students reported greater use of decision processes associated with self-reliance and personal ability (“individual role”).