Discussion

To our current knowledge, this is the first national study to examine associations between COVID-19 testing uptake and mental disorders. These findings support our hypothesis that adults with test-confirmed COVID-19 were at significantly lower risk for severe depression, severe anxiety, eating disorders and suicidal ideation compared with those with suspected or physician-diagnosed COVID-19 unconfirmed by testing. These findings corroborate previous research indicating that individuals who suspected that they had COVID-19 but lacked confirmatory testing were more susceptible to exacerbated mental health problems due to fear of infection.^{Reference Quadros, Garg, Ranjan, Vijayasarathi and Mamun11,Reference Alimoradi, Ohayon, Griffiths, Lin and Pakpour12} These findings suggest that testing may help adults with COVID-19-like symptoms to reduce the risk for mental distress associated with the fear and uncertainty of infection and consequent restrictions.

Additionally, we found no significant difference in risk for severe depression and suicidal ideation between adults with test-confirmed COVID-19 and those without COVID-19 symptoms. Considering that studies suggest COVID-19 infection increases the risk for neuropsychiatric symptoms,^{Reference Boldrini, Canoll and Klein7,Reference Taquet, Geddes, Husain, Luciano and Harrison8} we conclude that testing may help attenuate the risk for severe depression and suicidal ideation exacerbated by COVID-19 symptoms. Significant differences found in severe anxiety and eating disorders between these two groups might be due to COVID-19 infection rather than testing.^{Reference Boldrini, Canoll and Klein7,Reference Taquet, Geddes, Husain, Luciano and Harrison8} Some people with a history of COVID-19 infection might suffer long-term physical and mental sequelae of the disease (‘long COVID’) and adverse effects of medications treating infections, which could fuel excessive worry and dysregulate eating behaviours/patterns.^{Reference Yuan, Zheng, Wang, Sun, Gong and Huang13,Reference Sikaroudi, Zonooz, Ebrahimi, Jebraili, Farsi and Talebi14} These findings suggest that mental health professionals should be ready to address individuals’ mental health problems that develop after COVID-19 illness. To prevent mental disorders associated with severe infection, mental health professionals should also encourage preventive measures (e.g. testing, vaccination) and promote people's health literacy.^{Reference Brewer and Abad15}

This study has limitations. First, the generalisability may be limited because participants represented adults enrolled in post-secondary education. Although our sample showed a wide age range (18–65+ years), the majority were young adults. Older adults may have different levels of fear and tolerance of uncertainty regarding COVID-19. Future studies might examine the role of testing uptake in mental health across different populations/settings. Moreover, causal inferences should be interpreted with caution in this study as cross-sectional data restricted our ability to determine the temporal order between testing uptake and mental disorders that were measured simultaneously. Longitudinal studies are therefore needed to help assess the temporal links. Despite these limitations, this study provides empirical evidence for the associations between COVID-19 testing uptake and mental disorders through a large representative cohort, controlled for covariates to reduce possible confounding effects.

This study underscores the vital role of mental health professionals in public health, providing preliminary support for another potential benefit of public health efforts to encourage COVID-19 preventive measures,^{Reference Brewer and Abad15} namely promoting mental health. When coupled with other public health measures, timely COVID-19 testing can reduce the transmission of SARS-CoV-2 extensively and can also reduce the risk for severe depression, severe anxiety, eating disorders and suicidal ideation. Our findings suggest that encouraging COVID-19 testing and making testing more accessible will lessen the strain of the pandemic on our healthcare systems and public mental health, particularly during any resurgence of COVID-19 infections.