ObjectiveCrises such as the COVID-19 pandemic are known to exacerbate depression and anxiety, though their temporal trajectories remain unclear. The present study aims to investigate fluctuations in depression and anxiety using COVID-19 as a model crisis.Methods1,512 adults living in the U.S. enrolled in this online study on April 2nd, 2020 and were assessed weekly for 10 weeks (until June 4th, 2020; final n=537). Depression and anxiety were measured using the Zung Self-Rating Depression scale and State-Trait Anxiety Inventory (state subscale), respectively, along with demographic and COVID-related questions. Mixed-effects linear regression models were used to examine factors contributing to longitudinal changes in depression and anxiety.ResultsDepression and anxiety levels were high in early April, but declined over time (F(9,4824)=17.53, p<.001 and F(9,4824)=23.35, p<.001, respectively). In addition to demographic factors such as sex, age, income, and psychiatric diagnoses, we identified some overlapping and some distinct dynamic factors contributing to changes in depression and anxiety: worsening of weekly individual economic impact of COVID-19 increased both depression and anxiety, while increased seven-day change in COVID-19 cases, social media use, and projected pandemic duration were positively associated with anxiety, but not depression.ConclusionsAlongside evidence for overall emotional adaptation, these findings highlight overlapping (economic), yet distinct (change in COVID-19 cases, social media use, and projected COVID-19 duration) factors contributing to fluctuations in depression and anxiety throughout the first wave of COVID-19. These results provide insight into socioeconomic policies and behavioral changes that can increase emotional adaptation in times of crisis.