A systematic review and meta-analysis of longitudinal cohort studies comparing mental health before versus during the COVID-19 pandemic
Authors: Robinson Eric , Sutin Angelina R. , Daly Michael , Jones Andrew 
Published: March 2021

AbstractBackgroundIncreases in mental health problems have been observed in some studies during the COVID-19 pandemic. It is unclear whether changes have been large and experienced by most population sub-groups, persisted over time or been symptom specific.MethodsWe systematically reviewed and meta-analysed longitudinal cohort studies that examined changes in mental health among the same group of participants before and during the pandemic (PROSPERO: CRD42021231256). Searches for published and unpublished studies were conducted in January 2021. Changes in mental health (standardised mean change; SMC) were examined using meta-analyses.FindingsSixty-five studies were included. There was an overall increase in mental health symptoms that was most pronounced during March-April 2020 (SMC = .102 [95% CI: .026 to .192], p = 0.03) before significantly declining over time (May-July SMC = .067 [95% CI: -.022 to .157], p = .141). Compared to measures of anxiety (SMC = 0.13, p = 0.02) and general mental health (SMC = -.03, p = 0.65), increases in depression and mood disorder symptoms tended to be larger (SMC = 0.22, p < .001) and reductions over time appeared less pronounced. Increased mental health symptoms were observed across most population subgroups examined but there was no evidence of any change in symptoms among samples with a pre-existing mental health condition.InterpretationThere was a small increase in mental health symptoms soon after the outbreak of the COVID-19 pandemic that decreased and was comparable to pre-pandemic levels by mid-2020 among most population sub-groups and symptom types.FundingN/AResearch in contextEvidence before this studyThere have been reported increases in mental health problems during the outbreak of the COVID-19 pandemic. However, it is unclear whether changes in mental health problems have been symptom specific, how changes have differed across populations and whether increased mental health problems have persisted over time. We systematically reviewed and meta-analysed longitudinal cohort studies that examined mental health among the same participants prior to and during the pandemic in 2020. This approach allowed us to quantify the mental health burden associated with the outbreak of the pandemic and how it has changed over time. We searched Pubmed, SCOPUS, Web of Science and PsychInfo from January 2020 to January 11, 2021 and identified eligible unpublished articles available on pre-print servers.Added value of this studyWe identified 65 eligible articles that reported 201 comparisons of mental health pre vs. post pandemic outbreak. Meta-analysis indicated that longitudinal cohort studies that examined mental health prior to and during the COVID-19 pandemic in 2020 showed a significant but statistically small increase in mental health symptoms. The overall increase in mental health symptoms was most pronounced during the early stages of the pandemic (March-April), before decreasing and being generally comparable to pre-pandemic levels by mid-2020.Compared to anxiety and general measures of mental health functioning, increases tended to be larger in depressive symptoms and although statistically small, remained elevated past the early stages of the pandemic. Increases in mental health symptoms were observed across most population sub-groups, but there was no evidence of a change in mental health symptoms among samples of participants with a pre-existing mental health condition.Implications of all the available evidenceFindings confirm that the initial outbreak of the pandemic was associated with a significant but statistically small increase in mental health symptoms. Given that small effects may have meaningful cumulative consequences at the population level, there is a need for continued mental health provision and monitoring particularly during periods of the pandemic when infection rates and deaths are high. Further into the pandemic, mental health problems decreased significantly, which indicated recovery and resilience in overall mental health. Contrary to predictions made early in the pandemic, there was also no evidence of a worsening of mental health symptoms among samples of participants with a pre-existing mental health condition. Overall the results of the present analyses suggest that the pandemic may not have caused an unprecedented and long lasting mental health crisis, instead there appears to have been resilience in mental health.