Cross-sectional Study about Risk Factors for Major Depression and Suicidal Ideation Following the COVID-19 pandemic in Japan Just before the Arrival the of Third wave: The First Survey from "The Prospective Cohort Study of Physical and Mental Health under the COVID-19 Pandemic in Japan"

Background: Due to the COVID-19 pandemic in Japan, we have been suffering from substantially stressful situation such as a new normal lifestyle including self-quarantine or serious economic recession. In fact, the suicidal number per month year-on-year have been increasing, in particular the situation of women is comparatively serious, since July in 2020 although it had been declining over these 10 years. Thus, there seems to be a serious concern about the physical and mental condition for Japanese people. In order to make an evidence-based decision for our public health, we need to understand exactly what is happening to us.

Method: The first survey was conducted at the end of October 2020 as a part of "The prospective cohort study of mental and physical health under the COVID-19 pandemic in Japan" granted by the Research Institute of Economy, Trade and Industry. For major depression and suicidal ideation, Adjusted odds ratio of each risk factor was estimated via multivariate logistic regression analysis, and then were respectively evaluated, including financial situation, communication with others, social rhythm, daily activities, exercise and physical illness.

Results: Eventually the data of 16,642 individuals were collected and included in the analysis. Major depression and suicidal ideation were more common among younger people (especially for women), those with lower household income and savings, those with lower incomes than the last year. On the other hand, it was shown that odds ratio of major depression and suicidal ideation were lower among those with more appropriate communication with others or those with more any individuals to talk with in case of trouble and those with more regular social rhythms as compared to those without.

Conclusion: Despite a cross-sectional study, several potential risk factors were identified. Further investigation is required through our additional cohort study.