XI. GENERAL DISCUSSION: CHILDREN'S ADJUSTMENT AND ADAPTATION FOLLOWING THE BIRTH OF A SIBLING

Suicide mortality rates in Japan before and beyond the COVID-19 pandemic era

Statistical analyses from Japan reported increasing suicides in 2020, first in the world, proving the severity of the public health crisis during the COVID-19 pandemic; however, so far, international suicides have not been shown to be objectively increasing at population level. Followed studies reported the existence of a substantial heterogeneity of suicides among subgroups and time-lag impacts. Against public health crisis in Japan, policymakers, psychiatrists and public health personnel should prioritize improving suicide prevention programs following evidence-based policymaking. Understanding how/what factors relate to the COVID-19 pandemic and what other factors have shaped the increasing suicide numbers since 2020 through objectively well-controlled/fine-grained analyses of high-quality longitudinal/cross-sectional data at the individual, regional, and national levels is important for identifying the reasons for the recent trend. For this purpose, this study examined suicide statistics, statistical analysis methods, and their interpretations. Recent analyses suggest an increased suicide risk among females <50 years and males <30 years in 2020-2022. Notably, time-series analyses revealed that adolescent suicides began increasing before the pandemic, while working-age female suicides sharply increased synchronously with the pandemic outbreak. Causality analyses suggest that social issues facing Japan and recent global psychosocial and socioeconomic transformations are risk factors for suicide in high-risk groups. Finally, this report demonstrates the importance of providing appropriate support based on an objective understanding of individuals who are at risk for suicide, without being bound by traditional established knowledges.

Sibling effects on problem and prosocial behavior in childhood: Patterns of intrafamilial "contagion" by birth order

We investigated longitudinal relations between siblings' problem and prosocial behavior, measured by the Strengths and Difficulties Questionnaire, among different sibship sizes in the UK's Millennium Cohort Study. We identified 3436 families with two children and 1188 families with three children. All children (cohort members and their older sibling [OS]) had valid data on behavior at two time points (in 2004 and 2006). Using structural equation model, we found that for internalizing and externalizing problems, OSs (MOS1 = 6.3 years, MOS2 = 9.1 years at T1) exerted a dominant effect on younger siblings (Mage = 3.12 years at T1; 49.7% boys) across sibship sizes. For prosocial behavior, there was OS dominance in two-child families and youngest sibling dominance in three-child families.

Temporal Fluctuations of Suicide Mortality in Japan from 2009 to 2023 Using Government Databases

In Japan, suicide mortalities consistently decreased before the COVID-19 pandemic (from 2009 to 2019) but, conversely, increased after the pandemic outbreak from 2020 to 2022. To provide up-to-date suicide statistics in Japan, this study determined the temporal fluctuations of standardized suicide mortalities (SMRs), disaggregated by sex and age, by joinpoint regression analysis using the government suicide database, named the "Basic Data on Suicide in Region". From January 2009 to December 2023, three temporal fluctuation patterns of SMRs pertaining to working age and older adults were detected, such as attenuations of decreasing trends before the COVID-19 pandemic (from around the mid-2010s), a sharply increasing trend that coincided with the pandemic outbreak, and gradually decreased during the pandemic, but no changes at the end of the COVID-19 pandemic. In particular, the SMRs of working-age females sharply increased concurrently with the pandemic outbreak, whereas those of males did not change. However, before the pandemic, decreasing trends of the SMRs of working-age males diminished in the mid-2010s, but those of females consistently decreased. The SMRs of working-age males indicated non-significant but sharply increasing trends in early 2022, a trend that was not observed for females. In contrast to working-age adults, the SMRs of adolescents already began to increase in the mid-2010s and also indicated consistently increasing trends between the periods during and after the pandemic. These results suggest, contrary to our expectations, that the impacts of both the outbreak and end of the COVID-19 pandemic were limited regarding the increase in SMRs from 2020. Therefore, when revising suicide prevention programs in the post-COVID-19 era, it should be noted that focusing on pandemic-associated factors alone is not sufficient.