Sex Differences in Adolescent Depression Trajectory Before and Into the Second Year of COVID-19 Pandemic

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 3 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 to February 2020) and during-pandemic (March 2020 to 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, 0.15 SD 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 to -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.

Diversity & inclusion statement: We worked to ensure that the study questionnaires were prepared in an inclusive way. We worked to ensure sex and gender balance in the recruitment of human participants. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. We actively worked to promote sex and gender balance in our author group. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work.