遠藤 香織

This study offers an in-depth analysis of Japan's suicide trends three years after the COVID-19 outbreak. Using data from the National Police Agency (January 2010-May 2023), we examined suicide rates across genders and age groups. Employing the quasi-Poisson regression, we predicted monthly death counts. Findings indicate a steady rise in female suicides from April 2020 to January 2023. Notably, male cohorts aged 50-59 and over 80 in 2022 displayed heightened death rates. While these trends may reflect the impacts of the pandemic, it is essential to consider other factors, including socio-economic changes, to fully understand the context of Japan's suicide patterns.

Abstract Previous studies reported decreased glutamate levels in the anterior cingulate cortex (ACC) in non-treatment-resistant schizophrenia and first-episode psychosis. However, ACC glutamatergic changes in subjects at high-risk for psychosis, and the effects of commonly experienced environmental emotional/social stressors on glutamatergic function in adolescents remain unclear. In this study, adolescents recruited from the general population underwent proton magnetic resonance spectroscopy (MRS) of the pregenual ACC using a 3-Tesla scanner. We explored longitudinal data on the association of combined glutamate-glutamine (Glx) levels, measured by MRS, with subclinical psychotic experiences. Moreover, we investigated associations of bullying victimization, a risk factor for subclinical psychotic experiences, and help-seeking intentions, a coping strategy against stressors including bullying victimization, with Glx levels. Finally, path analyses were conducted to explore multivariate associations. For a contrast analysis, gamma-aminobutyric acid plus macromolecule (GABA+) levels were also analyzed. Negative associations were found between Glx levels and subclinical psychotic experiences at both Times 1 (n = 219, mean age 11.5 y) and 2 (n = 211, mean age 13.6 y), as well as for over-time changes (n = 157, mean interval 2.0 y). Moreover, effects of bullying victimization and bullying victimization × help-seeking intention interaction effects on Glx levels were found (n = 156). Specifically, bullying victimization decreased Glx levels, whereas help-seeking intention increased Glx levels only in bullied adolescents. Finally, associations among bullying victimization, help-seeking intention, Glx levels, and subclinical psychotic experiences were revealed. GABA+ analysis revealed no significant results. This is the first adolescent study to reveal longitudinal trajectories of the association between glutamatergic function and subclinical psychotic experiences and to elucidate the effect of commonly experienced environmental emotional/social stressors on glutamatergic function. Our findings may deepen the understanding of how environmental emotional/social stressors induce impaired glutamatergic neurotransmission that could be the underpinning of liability for psychotic experiences in early adolescence.

ABSTRACT Background Research suggests gender inequalities in adolescent mental health are context dependent. This implies they may be preventable through social/structural change. However, there is also some evidence that gender mental health gaps arelargerin ostensibly more gender equal societies, e.g., 2-3-fold larger in the UK vs. Japan. Using data and methods that overcome important limitations of existing evidence, we tested the hypothesis that gender inequalities in depressive symptom trajectories are larger in London than in Tokyo, and that these differences are not due to incomparable measurement. Methods We used three waves of data from representative adolescent cohorts in Tokyo (TTC;n=2,813) and London (REACH;n=4,287) (n=7,100; age 11-16y). We used multigroup and longitudinal confirmatory factor analysis to examine measurement invariance of the 13-item Short Mood and Feelings Questionnaire (SMFQ) across cohorts, genders, and ages. Latent growth models compared depressive symptom trajectories of boys and girls in London and Tokyo. Outcomes Scalar invariance was well-supported. In London, gender inequalities in depressive symptoms were evident at age 11y (girls: +0·8 [95% CI: 0·3-1·2]); in Tokyo, the difference emerged between 11-14y. In both places, the disparity widened year-on-year, but by age 16y was around twice as large in London. Annual rate of increase in depressive symptoms was around four times steeper among girls in London (1·1 [0·9-1·3]) vs. girls in Tokyo (0·3 [0·2-0·4]). Interpretation Gender inequalities in emotional health are context dependent and may be preventable through social/structural change. Funding Japanese Society for the Promotion of Science; Economic and Social Research Council. RESEARCH IN CONTEXT Evidence before this study Women are around two-to-four times more likely than men to experience emotional problems such as depression and anxiety. Our understanding of the causes is surprisingly limited. Typically, these gender inequalities in emotional health emerge in early adolescence, at around the age of puberty, so much research has focussed on biological explanations. However, a growing body of evidence suggests gender inequalities in adolescent mental health may be context dependent, varying in size – and sometimes direction – across countries. This implies it may be possible to prevent the excess of mental distress among teenage girls through social/structural change. However, there is also some evidence to suggest that gender inequalities in teenage mental health arelarger, on average, in countries with higher levels of societal gender equity, e.g., around 2-3 times larger in the UK (which ranks 15^thon global gender equity) compared with Japan (ranked 125^th). Reasons for this seemingly paradoxical trend are unclear. However, there are important limitations to the international evidence that preclude robust inference about the contexts and conditions that give rise to (and those that mitigate and prevent) gender inequalities in emotional health. It is mostly cross-sectional, relates to older age groups, or – importantly – fails or is unable to robustly examine measurement invariance between countries. We reviewed the reference lists in two successive reviews (published in 2000 and 2017) on the causes of gender inequalities in depression and searched PubMed for original and review articles published as of January 2023. Search terms included: gender inequalities (sex/gender differences, inequalities, disparities, etc.) AND mental health (mental distress, depression, depressive symptoms, etc.) AND young people (child*, adolesc*, youth, etc.) AND international comparisons (international comparisons, cross-cohort, cross-cultural, etc.). We screened titles and abstracts to identify studies with longitudinal data on mental health in population-based adolescent samples. We found: one cross-sectional study reporting gender inequalities in mental distress and wellbeing at age 15 years in 73 countries, with measurement invariance considered at the regional level (e.g., Americas, Eastern Mediterranean); one cross-sectional study of all age groups (except children under 12) in 90 countries, with no examination of measurement invariance; and four longitudinal studies comparing gender inequalities in mental health across countries in mid-adolescence, that either (a) used unrepresentative samples, (b) compared countries with very similar levels of societal gender equity, or (c) did not examine – or only partly supported – measurement invariance between countries. Added value of this study We used three waves of data from large, representative cohorts of young people in Tokyo and London and examined (a) the extent to which a widely used measure of depressive symptoms is invariant (comparable) across place, gender, and age, and (b) whether inequalities in depressive symptom trajectories between adolescent boys and girls are larger in London than in Tokyo. We found strong evidence that inequalities in depressive symptom trajectories between adolescent boys and girls are around twice as large, and may emerge earlier, among young people in London than in Tokyo. Notably, the annual rate of increase in depressive symptoms from age 11 to age 16 was around four times steeper among girls in London than among girls in Tokyo. Importantly, we found little evidence to suggest these differences are due to incomparable measurement. We co-wrote this paper with ten young people, five in London and five in Tokyo, and their perspectives are integrated throughout and presented in the Supplement. Implications of all the available evidence There is strong evidence that the size and course of gender inequalities in emotional health are driven by social/structural context. Against a backdrop of high and rising rates of emotional health problems among young women and girls in many countries, there is an urgent need to understand the contexts and conditions that enable young girls to thrive.

BACKGROUND: Understanding the etiology of psychosis is essential to the development of preventive interventions. The COVID-19 pandemic provides a rare natural experiment that can expand our understanding of the role of social factors in the trajectories and etiology of psychosis across adolescence, particularly in Tokyo where the prevalence of actual COVID-19 infection remained low. We hypothesized that the likelihood of self-reporting psychotic experiences (PEs) would increase following the onset of the COVID-19 pandemic. METHODS: The Tokyo Teen Cohort (TTC) is a prospective cohort study of adolescents in the general population of the Tokyo metropolitan area, followed from age 10 to 16 years. We used multi-level linear regression models to test the associations between the phase of the COVID-19 pandemic and self-reported PEs. RESULTS: Among 1935 adolescents included in the analysis, a rapid increase in PEs occurred at the onset of the COVID-19 pandemic, following approximately 6 years of steady decline across prior waves. This association was more pronounced for boys compared to girls. This increase became more pronounced as the pandemic moved into later phases, defined based on contemporaneous sociopolitical changes in Tokyo (i.e. changes to school closure, social distancing guidelines, and the state of emergency status). CONCLUSIONS: The steady decline in PEs across adolescence was halted and reversed concurrent with the COVID-19 pandemic onset, despite very low rates of COVID-19 infection. This implicates COVID-19 related socioenvironmental factors as contributory etiological factors in the development of PEs in this adolescent cohort.

Abstract Adolescence is a critical period for psychological difficulties. Auditory mismatch negativity (MMN) and gamma-band auditory steady-state response (ASSR) are representative electrophysiological indices that mature during adolescence. However, the longitudinal association between MMN/ASSR and psychological difficulties among adolescents remains unclear. We measured MMN amplitude for duration and frequency changes and ASSR twice in a subsample (n = 67, mean age 13.4 and 16.1 years, respectively) from a large-scale population-based cohort. No significant longitudinal changes were observed in any of the electroencephalography indices. Changes in SDQ-TD were significantly associated with changes in duration MMN, but not frequency MMN and ASSR. Furthermore, the subgroup with higher SDQ-TD at follow-up showed a significant duration MMN decrease over time, whereas the subgroup with lower SDQ-TD did not. The results of our population neuroscience study suggest that insufficient changes in electroencephalography indices may have been because of the short follow-up period or non-monotonic change during adolescence, and indicated that the longitudinal association with psychological difficulties was specific to the duration MMN. These findings provide new insights that electrophysiological change may underlie the development of psychosocial difficulties emerging in adolescence.

OBJECTIVE: Evidence on the impact of the COVID-19 pandemic on adolescent mental health is mixed and does not disentangle natural age-related changes. We compared depressive symptoms among 16-year-olds surveyed, at a fourth wave, before or during the pandemic, while accounting for expected trajectories of within-person change based on three prior waves. METHOD: In this longitudinal cohort of 3,171 adolescents in Tokyo, Japan, adolescents were grouped based on their age 16 survey timing: pre-pandemic (February 2019-February 2020) and during-pandemic (March 2020-September 2021). Depressive symptoms were self-reported using the Short Mood and Feelings Questionnaire. Mixed-effect models were fitted to assess group differences while controlling for previous trends. Variations by sex, household income, and pandemic phase (early, late first-year, and second-year) were examined. RESULTS: Of 2,034 eligible adolescents, 960 (455 girls) were assessed before and 1,074 (515 girls) during the pandemic. Overall, depressive symptoms increased by 0.80 points (95%CI 0.28-1.31, 0.15SD of the population average). This increase varied by sex and pandemic phase; for boys, the increase emerged in the late first-year phase and enlarged in the second-year phase (mean difference from pre-pandemic: 1.69, 0.14-3.24), whereas, for girls, it decreased in the early school-closure phase (mean difference: -1·98, -3·54- -0·41) and returned to the pre-pandemic level thereafter, with no additional increases during the pandemic. CONCLUSION: Into the second year of the COVID-19 pandemic, depressive symptoms of 16-year-olds worsened above the expected age-related change only in boys. Continuous monitoring and preventive approaches for adolescents at the population level are warranted.

Abstract Background Little information is available on the association between gender nonconformity during adolescence and subsequent mental health. While the distress related to gender nonconformity may be socially produced rather than attributed to individual-level factors, further research is needed to better understand the role of psychosocial factors in this context. Method We analyzed data from the Tokyo Teen Cohort, obtained through random sampling of adolescents born between 2002 and 2004. We used inverse probability weighting to examine the association of gender nonconformity at ages 12 and 14 as a time-varying variable with subsequent mental health at age 16, while accounting for time-fixed and time-varying confounders. Furthermore, we used a weighting approach to investigate the mediating role of modifiable psychosocial factors in this association, addressing exposure-mediator and mediator–mediator interactions. Results A total of 3171 participants were analyzed. Persistent gender nonconforming behavior at ages 12 and 14 was associated with subsequent depression (β = 2.02, 95% confidence interval [CI] 0.85 to 3.19) and psychotic experiences (β = 0.33, 95% CI 0.14 to 0.52) at age 16. The results remained robust in sensitivity analyses. Approximately 30% of the association between gender nonconformity and depression was consistently mediated by a set of psychosocial factors, namely loneliness, bullying victimization, and relationships with mother, father, and friends. Conclusions Persistent gender nonconformity during adolescence is associated with subsequent mental health. Psychosocial factors play a vital mediating role in this association, highlighting the essential need for social intervention and change to reduce stigmatization and ameliorate mental health challenges.

[This corrects the article DOI: 10.3389/fpsyt.2022.865907.].

Maternal breastfeeding has an impact on motor and emotional development in children of the next generation. Elucidating how breastfeeding during infancy affects brain regional structural development in early adolescence will be helpful for promoting healthy development. However, previous studies that have shown relationships between breastfeeding during infancy and cortical brain regions in adolescence are usually based on maternal retrospective recall of breastfeeding, and the accuracy of the data is unclear. In this study, we investigated the association between breastfeeding duration and brain regional volume in a population-neuroimaging study of early adolescents in Japan (N ​= ​207; 10.5-13.4 years) using voxel-based morphometry, which enabled us to analyze the whole brain. We evaluated breastfeeding duration as indexed by maternal and child health handbook records during infancy. The results showed a significant positive correlation between the duration of breastfeeding and gray matter volume in the dorsal and ventral striatum and the medial orbital gyrus. Post hoc exploratory analyses revealed that the duration of breastfeeding was significantly correlated with emotional behavior. Additionally, the volume in the medial orbital gyrus mediated an association between breastfeeding duration and emotional behavior. This is the first study to evaluate the effect of breastfeeding during infancy on regional brain volumes in early adolescence based on maternal and child health handbook records. Our findings shed light upon the importance of maternal breastfeeding for brain development related to emotional and motivational processing in early adolescence.