Modelling Changes in Anxiety-Depression and Traumatic Stress During the First Wave of the COVID-19 Pandemic in the UK: Evidence for Population Heterogeneity in Longitudinal Change (preprint)

Background: Research is needed to examine change in general population mental health since the beginning of the pandemic, while accounting for heterogeneity in mental health response. Methods: The COVID-19 Psychological Research Consortium (C19PRC) Study is a longitudinal, nationally representative, internet-based survey of UK adults. The current study analysed data from its first three waves of data collection: Wave 1 (March 2020, N =2025), Wave 2 (April 2020, N =1406) and Wave 3 (July 2020, N =1166). Anxiety-depression was measured using the Patient Health Questionnaire Anxiety and Depression Scale (a composite measure of the PHQ-9 and GAD-7) and COVID-19 related PTSD with the International Trauma Questionnaire. Changes in mental health outcomes were modelled across the three waves. Latent class growth analysis was used to identify subgroups of individuals with different trajectories of change in anxiety-depression and COVID-19 PTSD. Latent class membership was regressed on baseline characteristics. Outcomes: Overall prevalence of anxiety-depression remained stable, while COVID-19 PTSD reduced between Waves 2 and 3. Heterogeneity in mental health response was found, and hypothesised classes reflecting (i) stability, (ii) improvement, and (iii) deterioration in mental health were identified. Psychological factors were most likely to differentiate the improving, deteriorating and high-stable classes from the low-stable mental health trajectories. Interpretation: A low-stable profile characterised by little-to-no psychological distress (‘resilient’ class) was the most common trajectory for both anxiety-depression and COVID-19 PTSD. Monitoring of these trajectories is necessary moving forward, in particular for the ~30% of individuals with increasing levels of anxiety-depression. Funding Statement: Economic and Social Research Council (ES/V004379/1). Declaration of Interests: We declare that no competing interests exist. Ethics Approval Statement: Ethical approval was granted by the University of Sheffield (Ref. 033759). All participants provided informed consent.