Trajectories of depression and anxiety symptoms during the COVID-19 pandemic in a representative Australian adult cohort.

Objectives: To estimate initial levels of symptoms of depression and anxiety, and their changes during the early months of the COVID-19 pandemic in Australia; to identify trajectories of symptoms of depression and anxiety; to identify factors associated with these trajectories.

Design, Setting, Participants: Longitudinal cohort study; seven fortnightly online surveys of a representative sample of 1296 Australian adults from the beginning of COVID-19-related restrictions in late March 2020 to mid-June 2020.

Main Outcome Measures: Symptoms of depression and anxiety, measured with the Patient Health Questionnaire (PHQ-9) depression and Generalised Anxiety Disorder (GAD-7) scales; trajectories of symptom change.

Results: Younger age, being female, greater COVID-19-related work and social impairment, COVID-19-related financial distress, having a neurological or mental illness diagnosis, and recent adversity were each significantly associated with higher baseline depression and anxiety scores. Growth mixture models identified three latent trajectories for depression symptoms (low throughout the study, 81% of participants; moderate throughout the study, 10%; initially severe then declining, 9%) and four for anxiety symptoms (low throughout the study, 77%; initially moderate then increasing, 10%; initially moderate then declining, 5%; initially mild then increasing before again declining, 8%). Factors statistically associated with not having a low symptom trajectory included mental disorder diagnoses, COVID-19-related financial distress and social and work impairment, and bushfire exposure.

Conclusion: Our longitudinal data enabled identification of distinct symptom trajectories during the first three months of the COVID-19 pandemic in Australia. Early intervention to ensure that vulnerable people are clinically and socially supported during a pandemic should be a priority.