The impact of the initial and 2ndnational COVID-19 lockdown on mental health in young people with and without pre-existing depressive symptoms
Authors: Joensen Andrea , Danielsen Stine , Andersen Per Kragh , Groot Jonathan , Strandberg-Larsen Katrine 
Published: November 2021

SummaryBackgroundThe evidence on mental well-being and loneliness among young people during the initial lockdown is mixed, and little is known about the long-lasting impact of the sequential lockdowns. We examine changes in young people’s mental health from before to during the initial and second more prolonged lockdown, and whether women and those with pre-existing depressive symptoms were disproportionally impacted.MethodsParticipants reported on mental health indicators in an ongoing 18-year data collection in the Danish National Birth Cohort and in a COVID-19 survey, including 8 data points: 7 in the initial lockdown, and 1 year post. Changes in quality of life (QoL), mental well-being, and loneliness were estimated with random effect linear regressions on longitudinal data (N=32,985), and linear regressions on repeated cross-sections (N=28,579).FindingsInterim deterioration in mental well-being and loneliness was observed during the initial lockdown, and only in those without pre-existing depressive symptoms. During the second lockdown, a modest deterioration was again observed for mental well-being and loneliness. QoL likewise only declined among those without pre-existing symptoms, where women showed a greater decline than men. QoL did not normalise during the initial lockdown and remained at lower levels during the second lockdown. These findings were not replicated in the repeated cross-sections.InterpretationExcept for an interim decrease in mental health during lockdown, and only in those without pre-existing depressive symptoms, this study’s findings do not suggest a substantial detrimental impact of the lockdowns. Potential methodological differences in-between studies are a possible explanation for the mixed evidence.FundingThe Velux FoundationResearch in contextEvidence before this studyWe searched PubMed, PsycINFO, MedrXiv, and PsyArXiv with the terms (“Mental*” OR “Psychological*” OR “Emotional*”) AND (“Youth” OR “Young Adult*”) AND (“COVID*” OR “Coronavirus” OR “Lockdown*”) for articles published in English between January 1st2020 and October 1st2021. Included studies varied in terms of quality of data used but overall studies reported a detrimental impact of the lockdowns on young people’s mental health. However, the evidence on mental well-being and loneliness has shown to be inconsistent and with signs of resilience. Young people, women, and those with a pre-existing mental disorder have been identified as vulnerable subgroups, but only a few studies investigating mental health in individuals with a pre-existing mental disorder included a pre-lockdown measurement. The included studies also demonstrated that there is a gap in the evidence in understanding how mental health changed week by week, as well as the long-term impact over the course of the lockdowns.Added value of this studyWith longitudinal data, this study shows an interim impact of the initial and second lockdown on mental health during the COVID-19 pandemic in young individuals without pre-existing symptoms in Denmark. Since commencement of the initial lockdown, the levels of mental health returned to before levels, but one year after the initial lockdown, the levels were still lower than before lockdown in young people without pre-existing depressive symptoms. Young individuals with pre-existing depressive symptoms did not experience more detrimental impact of the lockdown, but rather indication of resilience or even improvements in mental health were observed. A disproportional impact of the lockdown on women compared to men was only observed for QoL, as women without pre-exiting depressive symptoms experienced a greater decline in QoL than men without pre-existing depressive symptoms. However, findings based on the repeated cross-sectional data did not show similar interim impact – but instead no – or clinically irrelevant impact. Thus, taken together our findings do not suggest a substantial lasting impact of the lockdowns on mental health among young individuals.Implications of all available evidenceA great majority of earlier studies suggest that the lockdowns due to the COVID-19 pandemic have had substantial detrimental impact on mental health, and that women and those with a pre-existing mental disorder constitute vulnerable subgroups. However, these studies vary considerably in terms of method applied. Our findings emphasise the importance of the use of different data setups, as well as methodology applied for the investigation of mental health. More studies based on high-quality data used in different settings are needed to fully understand the impact of the lockdowns on young people’s mental health, including potential disproportional impact on vulnerable subgroups.