Age-related differences in depressive symptoms and coping strategies during the COVID-19 pandemic in Japan: A longitudinal study

OBJECTIVE: The coronavirus 2019 (COVID-19) pandemic has particularly influenced the mental health of younger adults; accordingly, this study investigated age-related factors related to mental health and provided suggestions related to mental health recovery. METHODS: A web-based longitudinal survey was conducted from 2020 to 2021 in Japan. The survey consisted of the Patient Health Questionnaire-9 (PHQ-9), used to measure depressive symptoms as a response variable, and an anger questionnaire and coping strategy scale to assess explanatory variables. RESULTS: A total of 1468 participants were analyzed (valid response rate = 54.2%); 368 were younger adults (age range = 20–39), 667 were middle-aged adults (age range = 40–64), and 433 were aged adults (age range = 65–79). The PHQ-9 scores in the younger adults worsened over the three survey timepoints. State anger was strongly related to PHQ-9 scores in all age groups (standardized beta = 0.39–0.47), and state anger in the younger group was highest at all survey times, In the younger group, only nonadaptive coping strategies were related to PHQ-9 scores. Emotional support, venting, and humor adaptive strategies used by middle-aged and aged adults were most commonly used by younger adults; however, there were no significant relationships of these strategies with PHQ-9 scores in the younger group. CONCLUSION: The level of depressive symptoms among the younger adults might be considerably worse than the middle-aged and aged adult. The younger adults might not make use of strategies, hence, they might need advice and skill training of strategies.