Depressive response patterns during the COVID-19 pandemic from its onset to proclaimed termination: A 24-month representative observational study of the adult population

Despite the presence of individual differences in the depressive response patterns of adults during the COVID-19 pandemic, most studies have investigated overall population-level changes in depressive symptoms during the first year of the pandemic. This longitudinal repeated-measurement observational study obtained 39,259 observations from 4,361 adults assessed nine times over a 24-month period, spanning from the onset of the pandemic to its proclaimed termination. Using a Latent Change Score Mixture Model to investigate differential change patterns in depressive symptoms over time, five profiles were identified. Most adults revealed a consistently resilient (42.52%) or predominantly resilient pattern differentiated by an initial shock in symptomatology (13.17%). Another group exhibited consistently high depressive adversities (8.5%). One group showed mild deterioration with small increases in depressive symptomatology compared to onset levels (29.04%), and a second strong deterioration group exhibited substantial and clinically severe levels of gained symptoms over time during the pandemic (6.77%). Both deteriorating depressive response patterns predicted the presence of a psychiatric diagnosis and treatment-seeking behavior at the end of the pandemic. Together, the absence of a preexisting psychiatric diagnosis at the onset of the pandemic, severe symptom increases during, combined with reports of psychiatric treatment-seeking and diagnosis at its termination, indicated that the strongly deteriorating subgroup represents an additional group of adults struggling with depressive problems. Factors related to general adverse change (lower education levels, lone residence), initial shocks prior to recovery (frequent information seeking, and financial and occupational concerns at the onset of the pandemic), and resilience and recovery (older age, being in a relationship, physical activity) were identified. Binge drinking and belonging to an ethnic minority were influential predictors of the strongly deteriorating group. Major changes in response patterns occurred during the first three months of the pandemic, suggesting this period represents a window of sensitivity for the development long-lasting depressive states versus patterns of recovery and resilience. These findings call for increased vigilance of psychiatric symptoms during the initial phases of infectious disease outbreaks and highlight a specific target period for the implementation of preventive measures.