Changes in contamination-related obsessions and compulsions during the COVID-19 pandemic: A Norwegian longitudinal study

Background: Early stages of the COVID-19 pandemic have been associated with increasing obsessive-compulsive symptoms (OCS), but less is known regarding these symptoms' long-term trajectories. The aim of this study was to examine changes in contamination-related OCS in the Norwegian public during early and late stages of the pandemic, as well as characteristics that might be associated with these changes.Methods: In a longitudinal online survey, 12 580 participants completed self-report questionnaires in April 2020, including a retrospective assessment of contamination-related OCS severity (DOCS-SF) prior to COVID-19. In December 2020, 3405 (27.1%) of the participants completed the survey again.Results: In April, participants retrospectively recalled that their contamination-related OCS were lower prior to COVID-19 (d = 1.09). From April to December, symptoms slightly decreased (d =-0.16). The proportion of participants scoring above the clinical cut-off on DOCS-SF (>= 16) changed accordingly from 2.4% pre-COVID to 27.8% in April and 24.0% in December. Previous severity of contamination-related OCS and symptoms of distress related to COVID-19 were the most powerful predictors of contamination-related OCS severity during the pandemic.Conclusions: Elevated levels of contamination-related OCS were detected at both early and late stages of the pandemic, but the long-term symptom trend seems to be slightly declining.