Symptoms and risk factors of depression and PTSD in the prolonged COVID-19 pandemic: a longitudinal survey conducted from 2020 to 2022 in Japan

BACKGROUND: The present study aimed to explore changes in depression and posttraumatic stress disorder (PTSD) among the general population during the prolonged COVID-19 pandemic and to investigate risk factors and adaptive/nonadaptive strategies. METHODS: A web-based longitudinal survey was conducted across five timepoints from 2020 to 2022 in Japan. Depressive symptoms were measured using the Patient Health Questionnaire-9 (PHQ-9), PTSD was measured using Impact of Event Scale-Revised (IESR), and coping strategies were measured using Brief Coping Orientation to Problems Experienced (Brief COPE). Higher scores of PHQ-9 and IESR indicate more symptoms and Higher score of Brief COPE indicate that these means of coping are used very frequently. RESULTS: A total of 1,366 participants (mean age = 52.76, SD = 15.57) were analyzed. Regarding levels of depression, PHQ-9 scores in 2022 were lower than in 2020 and 2021 (all p < 0.01). Regarding levels of PTSD, IESR scores in 2022 were lower than in 2021 among females (p < 0.001). Being younger (β = -0.08 and − 0.13, both p < 0.01) and engaging in self-blame (β = 0.12 and 0.18, both p < 0.01) increased PHQ-9 scores regardless of sex. For males, not working (β = 0.09, p = 0.004) and having suffered an economic impact (β = 0.07, p = 0.003) were risk factors for depressive symptoms, and active coping (β = -0.10, p = 0.005) was associated with decreased depressive symptoms. For females, substance use (β = 0.07, p = 0.032) and behavioral disengagement (β = 0.10, p = 0.006) increased depressive symptoms, and females did not show strategies that decreased the symptoms. CONCLUSIONS: Levels of depression might have increased in the early stages of the pandemic and decreased in January 2022. Although males need to improve their economic situation to decrease depressive symptoms, adaptive strategies might be difficult to identify due to the prolonged pandemic among both sexes. In addition, the pandemic might be a depressive event but not a traumatic event among the general population, at least in Japan.