The Olympic Games are burdened with this inherent paradox of universal humanism and chauvinistic nationalism. Japan took palpable national pride in being the first ever Asian host of the modern Olympic Games in 1964 and in executing the mission with zeal, precision and order. Hosting the 2020 Olympics again represents Japan’s aspiration to play a significant role in the global world - and rebranding Tokyo as a leading global city – but this grand scheme has also invoked some antagonistic sentiments at home.

Reflecting on the 70th anniversary of the end of Japan's War, it is worth noting that teaching the history of World War II to Japanese children has always been difficult at best. As a subject fraught with contentions over textbook content and conflict between teachers and state bureaucracy, teaching war history has long been “a dreaded subject” for many school teachers. Japanese history education has been criticized for not going far and deeply enough to describe perpetrator history - especially the injury and death inflicted on tens of millions of Asian victims. At the same time, it has been admonished for the opposite: that it goes too far in promoting Japan's negative self-identity. This contest to shape hearts and minds of future citizens has long burdened Japan's history education in schools, and has yielded mixed results.

Benedict Anderson reminds us that modernity has been characterized by the emergence of nation-states that can mobilize the passion of young men to “die for the country” on a mass scale. Once mobilized, nationalist passion allows a soldier to believe “he is dying for something greater than himself, for something that will outlast his individual, perishable life in place of a greater, eternal vitality.” But after demobilization, this patriotic fervor withers, no longer fed or needed for everyday combat. In peacetime, the fervor that enabled death and destruction for national purpose no longer even has any social or moral legitimacy.

Maternal prenatal and postnatal psychological distress, including depression and anxiety, may affect children’s cognitive development. However, the findings have been inconsistent. We aimed to use the dataset from the Japan Environment and Children’s Study, a nationwide prospective birth cohort study, to examine this association. We evaluated the relationship between the maternal six-item version of the Kessler Psychological Distress Scale (K6) scores and cognitive development among children aged 4 years. K6 was administered twice during pregnancy (M-T1; first half of pregnancy, M-T2; second half of pregnancy) and 1 year postpartum (C-1y). Cognitive development was assessed by trained testers, using the Kyoto Scale of Psychological Development 2001. Multiple regression analysis was performed with the group with a K6 score ≤ 4 for both M-T1 and M-T2 and C-1y as a reference. Records from 1,630 boys and 1,657 girls were analyzed. In the group with K6 scores ≥ 5 in both M-T1 and M-T2 and C-1Y groups, boys had significantly lower developmental quotients (DQ) in the language-social developmental (L-S) area (partial regression coefficient: −4.09, 95% confidence interval: −6.88 – −1.31), while girls did not differ significantly in DQ for the L-S area. Among boys and girls, those with K6 scores ≤ 4 at any one or two periods during M-T1, M-T2, or C-1y did not have significantly lower DQ for the L-S area. Persistent maternal psychological distress from the first half of pregnancy to 1 year postpartum had a disadvantageous association with verbal cognitive development in boys, but not in girls aged 4 years.

This study evaluated the association between maternal magnesium intake (MMI) and childhood wheezing incidence in 3-year-old offspring. We hypothesised that higher MMI imparts anti-inflammatory and antioxidant effects that decrease childhood wheezing incidence in offspring. Data of 79 907 women (singleton pregnancy, ≥ 22 weeks) from the Japan Environment and Children’s Study (enrolled between 2011 and 2014) were analysed. Participants were categorised into quintiles of MMI (< 148·00, 148·00–187·99, 188·00–228·99, 229·00–289·99 and ≥ 290·00 mg/d), quintiles of adjusted MMI for daily energy intake (aMMI) (< 0·107, 0·107–0·119, 0·120–0·132, 0·133–0·149 and ≥ 0·150 mg/kcal) and MMI levels either below or above the ideal value (< 310·00 or ≥ 310·00 mg/d). Multivariable logistic regression analysis was performed to calculate OR for the incidence of childhood wheezing in offspring among participants in each MMI category, with the lowest MMI group considered the reference group. Maternal demographic, socio-economic, medical and other nutrient intake backgrounds were considered potential confounding factors. The adjusted OR (aOR) for childhood wheezing in the offspring of women with the highest MMI was 1·09 (95 % CI, 1·00, 1·20), whereas that calculated based on aMMI categories and offspring of women with above-ideal MMI levels remained unchanged. The highest MMI was associated with slightly increased childhood wheezing incidence in the offspring. MMI during pregnancy had an insignificant clinical impact on this incidence; moreover, modifying MMI would not significantly improve childhood wheezing incidence in offspring. Therefore, further studies should clarify the association between other prenatal factors and childhood wheezing incidence in offspring.

Maternal prenatal psychological distress, including depression and anxiety, may affect offspring’s motor/cognitive development. However, research findings have been inconsistent. We used a dataset from the Japan Environment and Children’s Study to evaluate associations between maternal six-item Kessler Psychological Distress Scale (K6) scores and motor/cognitive development among offspring at two years of age. Their offspring’s motor/cognitive development was assessed using the Kyoto Scale of Psychological Development 2001. Records for 1859 male and 1817 female offspring were analyzed. The maternal K6 was administered twice during pregnancy: at a median of 14.6 weeks (M-T1) and 27.3 weeks (M-T2) of gestation. Multiple regression analysis was performed with the group with K6 scores ≤4 at both M-T1 and M-T2 as a reference. In the group with K6 scores ≥5 at both M-T1 and M-T2, male offspring had significantly lower developmental quotients (DQ) in the posture-motor area (partial regression coefficient [B]: −3.68, 95% confidence interval [CI]: −5.92 to −1.44) and language-social area (B: −1.93; 95%CI: −3.73 to −0.12), while female offspring had a lower DQ for the language-social area (B: −1.95; 95%CI: −3.73 to −0.17). In those with K6 scores ≥5 only at M-T1 or M-T2, male and female offspring did not differ significantly in DQ for any area. Continuous maternal psychological distress from the first to the second half of pregnancy was associated with lower motor and verbal cognitive development in male offspring and lower verbal cognitive development in female offspring at 2 years compared with the group without persistent maternal prenatal psychological distress.

Maternal prenatal psychological distress, which includes depression and anxiety, affects the onset of autism spectrum disorder (ASD). However, there is no consistent knowledge regarding at which term during pregnancy psychological distress affects the risk of ASD among children. We used a dataset obtained from the Japan Environment and Children’s Study, which is a nationwide prospective birth cohort study, to evaluate the association between the six-item Kessler Psychological Distress Scale (K6) and ASD among 3-year-old children. A total of 78,745 children were analyzed, and 355 of them were diagnosed with ASD (0.45%). The maternal K6 was administered twice during pregnancy: at a median of 15.1 weeks (M-T1) and at that of 27.4 weeks (M-T2) of gestation. Multivariate logistic regression analyses demonstrated that the group with a maternal K6 score of ≥5 at both M-T1 and M-T2 was significantly associated with ASD among the children (adjusted odds ratio, 1.440; 95% confidence interval, 1.104–1.877) compared to the group with a score of ≤4 at both M-T1 and M-T2. There was no significant difference between the group with a score of ≥5 only at M-T1 or M-T2 and that with a score of ≤4 at both M-T1 and M-T2. In conclusion, from the first to the second half of pregnancy, continuous maternal psychological distress was associated with ASD among 3-year-old children. Contrarily, in the group without persistent maternal psychological distress during pregnancy, there was no significant association.

We evaluated the association between maternal prenatal folic acid supplementation/dietary folate intake and motor and cognitive development in 2-year-old offspring using data from the Japan Environment and Children’s Study database. Neurodevelopment of 2-year-old offspring were evaluated using the Kyoto Scale of Psychological Development 2001. In total, data of 3839 offspring were analysed. For folic acid supplementation, a multiple regression analysis showed that offspring of mothers who started using folic acid supplements before conception had a significantly lower developmental quotient (DQ) in the postural-motor DQ area than offspring of mothers who did not use them at any time throughout their pregnancy (partial regression coefficient (B) −2·596, 95 % CI −4·738, −0·455). Regarding daily dietary folate intake from preconception to early pregnancy, a multiple regression analysis showed that the group with ≥ 200 µg had a significantly higher DQ in the language-social area than the group with <200 µg. The DQ was higher in the ≥ 400 µg group (B 2·532, 95 % CI 0·201, 4·863) than the 200 to <400 µg group (B 1·437, 95 % CI 0·215, 2·660). In conclusion, our study showed that maternal adequate dietary folate intake from preconception to early pregnancy has a beneficial association with verbal cognition development in 2-year-old offspring. On the other hand, mothers who started using folic acid supplements before conception had an inverse association with motor development in 2-year-old offspring. There were no details on the amount of folic acid in the supplements used and frequency of use. Therefore, further studies are required.