Although temperament has been regarded as an innate aspect of human personality, its association with proteins involved in embryonic development is unclear. Reelin, encoded by RELN, plays an important role in brain development. Herein, we investigated the association between the RELN rs7341475 (G/A) single nucleotide polymorphism, detected as a female-specific risk factor for schizophrenia, brain structure, and temperament to elucidate the role of RELN in the development of human personality. In this study, 1580 healthy young Japanese adults were genotyped for RELN rs7341475 and completed the Temperament and Character Inventory. Whole-brain analysis of covariance was conducted to investigate differences between genotypes in regional gray matter volume (rGMV) and cortical morphology. Additionally, multiple regression analysis was performed to examine the association of four temperaments with rGMV. Those statistical analyses were performed separately for males and females. Individuals with G/G homozygosity showed significantly greater rGMV in several areas of the brain, particularly the bilateral cingulate and temporal gyrus, as well as a larger value of fractal dimension in the left lateral occipital cortex. Furthermore, of the four temperaments, the novelty seeking was significantly and positively associated with rGMV in the right superior temporal gyrus, partially overlapping with areas where differences between the rs7341475 genotypes were detected. The above findings were detected only in females, but not in males. This is the first study to demonstrate the contribution of RELN rs7341475 to differences in brain structure in Japanese females, which may indicate vulnerability to schizophrenia and variations in human personality.

Certain behavioral characteristics of autism spectrum disorder can be found in otherwise healthy people. Individuals with difficulties in social adaptation may have subclinical autistic traits; however, effective biomarkers of these traits have not yet been established. There is a dire need for objective indices of these traits that combine behavior, brain images, and genetic information. In this study, we examined the association among a single nucleotide polymorphism of NRXN1 (rs858932; C/G), autistic traits, and brain structure in 311 healthy adults. We found that carriers of minor alleles (carriers of the G-allele) had significantly higher systemizing scores than major-allele (C-allele) homozygotes. Furthermore, the regional white matter volume in the right anterior limb of the internal capsule was significantly greater in carriers of the G-allele than in C-allele homozygotes. To the best of our knowledge, this is the first report of NRXN1 rs858932 being involved in systemizing and the brain structure of healthy adults. Our findings provide insight into the effects of genetics on autistic traits and their respective neural substrates.

Research suggests that parent-offspring brain similarities may underlie intergenerational transmission of psychopathology. However, most studies have focused on mothers and offspring, with few including fathers. This study aimed to extend understanding of parent-offspring neural similarities by examining parent-offspring trios. The study included 152 Japanese biological parent-offspring trios who participated in the Transmit Radiant Individuality to Offspring (TRIO) study. We analyzed the parent-offspring similarities in brain structural features (cortical thickness, surface area, local gyrification index, and subcortical volume) across different parent-offspring gender combinations (father-son, father-daughter, mother-son, and mother-daughter). Additionally, we investigated the relationship between brain similarities and similarities in intelligence and personality traits in parents and offspring. Our findings confirmed that correlations in brain structural features between father-offspring or mother-offspring dyads were significantly stronger than those between unrelated individuals. Notably, both sons and daughters exhibited brain regions similar to their fathers only, mothers only, both parents, or neither parent. Furthermore, a significant association was observed between similarities in general intelligence and the surface area of auditory regions in both father-offspring and mother-offspring dyads. These results provide valuable insights into the genetic and environmental factors influencing brain development and aging across generations. This study is expected to contribute to future research elucidating the mechanisms underlying the intergenerational transmission of psychiatric disorders.

BACKGROUND AND PURPOSE: Ginkgo biloba extract (GBE) reportedly ameliorates cognitive function in patients with chronic cerebrovascular insufficiency. However, its efficacy in healthy adults is ambiguous. It was reported that concentrations of terpene lactones, active components of GBE that are present in very low concentrations in the brain, were significantly increased following administration of a mixture of GBE, sesame seed, and turmeric (GBE/MST) in mice. This study aims to investigate the effectiveness of GBE/MST on the cognitive function of healthy adults by comparing it with that of GBE alone. METHODS: Altogether, 159 participants providing informed consent will be recruited from a population of healthy adults aged 20-64 years. Normal cognitive function at baseline will be confirmed using the Japanese version of the Montreal Cognitive Assessment battery. Participants will be randomly assigned in a double-blind manner to the GBE/MST, GBE, and placebo groups in a 1:1:1 ratio. The Wechsler Memory Scale, Trail Making Test, and Stroop Color and Word Test will be used to assess the memory and executive functions at baseline and at the endpoint (24 weeks). For biological assessment, resting state functional magnetic resonance imaging (rs-fMRI) will be performed simultaneously with the neuropsychological tests. DISCUSSION: This study aims to obtain data that can help compare the profile changes in memory and executive functions among participants consuming GBE/MST, GBE alone, and placebo for 24 weeks. Alterations in the default mode network will be evaluated by comparing the rs-fMRI findings between baseline and 24 weeks in the aforementioned groups. Our results may clarify the impact of GBE on cognitive function and the functional mechanism behind altered cognitive function induced by GBE components. TRIAL REGISTRATION: This study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR; registration number: UMIN000043494). This information can be searched on the website of the International Clinical Trials Registry Platform Search Portal of the World Health Organization under the Japan Primary Registries Network.

Abstract Altruistic social activity, such as giving support to others, has shown protective benefits on dementia risk and cognitive decline. However, the pathological mechanism is unclear. In the present study, we investigated the association between altruistic social activity and brain regional gray matter. Furthermore, to explore the psychological interplay in altruistic social activity, we tested mediating effect of depressive symptoms on brain regional gray matter. We performed a cross-sectional Voxel-Based Morphology (VBM) analysis including 8695 old adults (72.9±6.1 years) from Japan Prospective Studies Collaboration for Aging and Dementia (JPSC-AD) Cohort. We measured altruistic social activities by self-report questionnaire, depressive symptoms by Geriatric Depression Scale (GDS)-short version. We employed the whole-brain VBM method to detect relevant structural properties related to altruistic social activity. We then performed multiple regression models to detect the mediating effect of depressive symptoms on particular brain regional gray matter volume while adjusting possible physical and social lifestyle covariables. We found that altruistic social activity is associated with larger gray matter volume in posterior insula, middle cingulate gyrus, hippocampus, thalamus, superior temporal gyrus, anterior orbital gyrus, and middle occipital gyrus. Depressive symptoms mediated over 10% on altruistic social activity and hippocampus volume, over 20% on altruistic social activity and cingulate gyrus volume. Our results indicated that altruistic social activity might preserve brain regional gray matter where are sensitive to aging and cognitive decline. Meanwhile, this association may be explained by indirect effect on depressive symptoms, suggesting that altruistic social activity may mitigate the neuropathology of dementia.

Nutritional supplementation with medium-chain triglycerides (MCTs) has the potential to increase memory function in elderly patients with frailty and dementia. Our aim was to investigate the effects of MCT on cognitive and gait functions and their relationships with focal brain metabolism and functional connectivity even in healthy older adults. Participants were blindly randomized and allocated to two groups: 18 g/day of MCT oil and matching placebo formula (control) administered as a jelly stick (6 g/pack, ingested three times a day). Gait analysis during the 6-m walk test, cognition, brain focal glucose metabolism quantified by 18F-fluorodeocyglucose positron emission tomography, and magnetic resonance imaging-based functional connectivity were assessed before and after a 3-month intervention. Sixty-three healthy, normal adults (females and males) were included. Compared with the control group, the MCT group showed better balance ability, as represented by the lower Lissajous index (23.1 ± 14.4 vs. 31.3 ± 18.9; P < 0.01), although no time × group interaction was observed in cognitive and other gait parameters. Moreover, MCT led to suppressed glucose metabolism in the right sensorimotor cortex compared with the control (P < 0.001), which was related to improved balance (r = 0.37; P = 0.04) along with increased functional connectivity from the ipsilateral cerebellar hemisphere. In conclusion, a 3-month MCT supplementation improves walking balance by suppressing glucose metabolism, which suggests the involvement of the cerebro-cerebellar network. This may reflect, at least in part, the inverse reaction of the ketogenic switch as a beneficial effect of long-term MCT dietary treatment.

<title>Abstract</title>Aging societies are one of the major problems faced in the modern world. Promoting subjective wellbeing is a key component in helping individuals positively accept and adapt to psychological and physical changes during their aging process. Tourism is one of the activities that have been demonstrated to promote subjective wellbeing. However, motivation for tourism and its benefits to subjective wellbeing among the older adults have rarely been discussed. The current study aimed to investigate whether tourism contributes to the subjective wellbeing of older adults. We examined the relationships between travel frequency, subjective wellbeing, and the personal trait of curiosity, mediated by the factor of family budget situation. The results demonstrated that diverse curiosity motivates individuals to travel; thus, diverse curiosity positively correlates to subjective wellbeing, both directly as well as indirectly through travel frequency. However, this relationship is limited by the factor of family budget, with tourism contributing to the subjective wellbeing of only well-off older adults. This study concludes that tourism has potential to contribute to subjective wellbeing during later stages of life.

Background: Decreased bone mineral density (BMD) was associated with poorer cognitive function and increased risk of Alzheimer's disease (AD). However, objective evidence for the relationship between osteoporosis and AD in humans has not been extensively described. Objectives: We aimed to evaluate the relationships between BMD and the cortical volumes of brain regions vulnerable to AD; hippocampus, parahippocampal gyrus, precuneus, posterior cingulate, and angular gyrus, using voxel-based morphometry (VBM), to investigate the association between bone loss and AD. Methods: A cohort of 149 consecutive elderly participants who complained of memory disturbance underwent high-resolution structural brain magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA). We used SPM12 software to conduct a voxel-based multiple regression analysis to examine the association between femoral neck BMD values and regional gray matter volume (rGMV) on structural T1-weighted MRI. Results: After adjusting for subject age, gender, total brain volume (TBV), and mini-mental state examination (MMSE) scores, the multiple regression analysis showed significant correlations between BMD loss and rGMV decline in the left precuneus, which is an important neural network hub vulnerable to AD. Conclusion: These data suggest that the bone and brain communicate with each other, as in "bone-brain crosstalk," and that control of BMD factors could contribute to cognitive function and help prevent AD.

In laboratory settings, creativity is measured using tasks of divergent as well as convergent thinking. It has been suggested that brain connectivity is important for creativity. In the present study, we investigated the associations of convergent thinking performance of compound Remote Associates Test (CRAT) with fractional anisotropy (FA) in diffusion tensor imaging and regional white matter (WM) volume (rWMV) in voxel-based morphometry in a large sample of healthy young adults (360 males and 280 females; mean age: 20.9 years, SD ​= ​1.6). We showed that CRAT performance was positively correlated with WM pathway property (i.e., FA) in the left fronto-occipital fasciculus and the left inferior longitudinal fasciculus, which play important roles in processing of language and concept. Further, CRAT performance was negatively correlated with rWMV in the widespread frontal temporal subcortical and cerebellar WM areas, suggesting the unique association of convergent thinking with WM connectivity.

Elongated axial length of the eye increases the morbidity of glaucoma. Myopia also associates with elongated axial length, and such ellipsoid shape of the eyeball strongly contributes its pathogenesis. Morphological features of the eyeballs, which could be important factors for developing glaucoma, have not been well described. The aim of this study was to investigate the three-dimensional (3D) topographic features of glaucomatous eyeballs with/without myopia to evaluate the potential of those features for predicting glaucoma. Using a 3.0-tesla MRI, volume-isotropic turbo-spin-echo acquisition T2-weighted images were obtained from 55 patients with glaucoma and 22 controls to delineate the eyeballs. Eyeball volumes, axial lengths and transverse lengths were semi-automatically calculated and compared between four groups: normal, myopia, glaucoma, and glaucoma with myopia. Both glaucoma and myopia increased the eyeball volume compared to the normal eyes. An increased anisotropy ratio (axial/transversus length) was observed in myopic eyes compared to normal, whereas in the glaucomatous eyes, with or without myopia, no increase in anisotropy ratio was observed. Increasing volume of eyes can be caused by myopia and glaucoma. Myopic eyes were ellipsoid in shape, but there was less anisotropy and a near-spherical shape in glaucomatous eyes, even in glaucomatous myopic eyes.

Cancer survivors are exposed to several risk factors for cognitive dysfunction, such as general anesthesia, surgical trauma, and adjuvant therapies. In our recent study we showed that thalamic volume reduction and attentional dysfunction occurred shortly after surgery. Here, we examined the 6-month prognosis of the 20 patients with breast cancer who underwent surgery. Seven patients did not receive any adjuvant therapy after the surgery and 13 patients received a hormonal therapy after the surgery. We assessed their attentional functions, and thalamic volumes shortly after and 6 months after surgery. We found a significant group x time interaction in the attentional functions (p = 0.033) and the right thalamus (p <  0.05, small volume correction), suggesting the thalamic volume reduction and attentional dysfunction recovered in patients without adjuvant therapy. Our findings provide a better understanding of the potential role of hormonal therapy in relation to the cognitive dysfunction of cancer survivors.