The present study utilized a large Chinese cohort to investigate the association between life changes (i.e., social contacts, lifestyles and family financial status) and mental health (i.e., depressive and anxiety symptoms) in children and adolescents during COVID-19 pandemic. Although the prevalence of depression and anxiety symptoms after pandemic was not higher than before, we did observe that students who reported that their social contacts, lifestyle and family financial status were negatively impacted during lockdown had increased risks of depression and anxiety symptoms at the same time. Such associations were no longer significant when we reassessed the students mental health one year after the lockdown, except for certain level(s) of study, social and outside activities and family income decline for both depression and anxiety, as well as diet for depression. After clustering on these students' life changes, we found that the group with severe impact on family financial status showed increased risk of depressive symptoms over the long term compared to the group who were relatively stable. Our study provides epidemiological knowledge of consequences of the COVID-19 pandemic and lockdown for children and adolescents’ mental health status in China with implementation of restrictive measures, highlighting the importance of developing tailor-made strategic plans for children and adolescents with different aspects of impact to address their unique needs in similar public health emergencies.
We found that there was a decreased trend in depressive and anxiety symptoms from W1 to W2 and W3 among the surveyed students during pandemic, which was unexpected and inconsistent with many previous studies[2, 35–37]. However, prior research on people’s mental health during COVID-19 also provide conflicting evidence[38–40]. The decreased prevalence of mental health problems could be due to many factors not restricted to better family functioning with increased family time and relationship building, reduction in peer stressors and academic pressures from the in-person school environment. In fact, our findings align with a Austrian study that reported better relationship quality associated with lower levels of psychological symptoms and a US study that found reduced mental health problems among youth during COVID-19[41, 42]. Moreover, we cannot rule out that students with mental health problems were more likely to drop out from the follow-up, resulting in decreased prevalence in the cohort.
Notably, however, for students who reported that their social contacts, lifestyle and family financial status were negatively impacted during lockdown, we observed increased risks of mental health problems at the same time point. As cross-sectional analyses cannot exclude reverse causation, it could also be that the mental health problems resulted in these life changes and negative self-reports. As a contrast, in the longitudinal analyses where depression and anxiety symptoms were collected one year after the life changes recorded, the degrees of associations were all attenuated, the dose-response relationship disappeared, and significant associations were only present at certain (levels) of changes. Although longitudinal analyses cannot establish causality, they provide stronger evidence for an association between an outcome and putative causative factors compared to cross-sectional analyses. However, even we assured that the exposures (at W2) occurred before the outcomes (at W3), the life changes between W2 and W3 during which the students had normally attended schools for one year were not adjusted for in our longitudinal analyses. For example, disturbed sleep time were associated with depressive symptoms in cross-sectional analyses, which is in line with previous studies [43–46] but not present in our longitudinal analyses. One explanation could be that the students’ sleep time were back to normal after W2. As we cannot distinguish which occurred first for the life changes and mental symptoms at W3, we chose to not adjust for life changes at W3 considering the possibility of reverse causation. Notably, the associations observed in the longitudinal analyses were unlikely to be violated by such unmeasured factors but just to be underestimated.
Among these findings, we observed several different risk factors for depressive and anxiety symptoms. For example, sleep time change, impact on diet and family financial status were more specifically associated with depression symptoms. We also noticed some inconsistency with previous studies. First, for BMI changes was not associated with mental health. This was inconsistent with previous studies that found in particular lockdown situation, the physical, nutritional and psychosocial factors were likely to create an unprecedented obesity environment for children and accompanying mental health problems[47, 48]. Notably, the height and weight data reported in W2 were from parental reports, which may introduce recall bias in our study. Second, the association between decreased exercise time and higher risk of anxiety symptoms highlights the importance of physical activity in mental health[12, 49], but its increase did not show protective effect, which differed from other studies[50, 51]. Third, the decreased electronic time also showed an association with increased depression and anxiety symptoms, which was different from some studies. This may be due to the strict management of these children at home by their caregivers, which could also be potential stressors. Meanwhile, the lack of variety in screen use was proven to be associated with mental health symptoms [52, 53].
The clustering analyses disentangled the life change patterns for children and adolescents, which also tended to influence their mental health status in different ways that was not obvious from the longitudinal analyses. Lifestyle changes seemed to play a less important role in the separation of clusters. Clustering analyses have the advantage of subgrouping subjects based on multidimensional factors which depict the global features, distinguish the effects, and provide insights for optimized intervention policies. Our clustering results were in line with previous clustering studies that demonstrated the heterogeneity in the population affected by the COVID-19 lockdown [54–56], but with larger sample size, multi-scales and longitudinal information.
Strength and limitations
The strength of this study includes the utilization of longitudinal data source, including one survey before the COVID-19 outbreak, one survey right after the COVID-19 lockdown, and one survey one year after the lifting of strict home confinements and prevention measures, which provides informative evidence for a potential impact of life changes on children and adolescents’ mental health during the COVID-19 pandemic. Moreover, our data-driven clustering analysis of multiple factors provided insights by revealing patterns and relationships that are not obvious or intuitive from variable-oriented methods. However, several limitations exist. First, self-reported changes in lifestyles may be influenced by recall bias and social desirability bias. Second, the study lacks data on the use of digital technology by children and adolescents to socialize with friends and to access social support during challenging times at COVID-19 lockdown, which has been demonstrated to alleviate negative feelings after social exclusion[57],[58]. Third, the study did not consider the social support received from family members, friends and others throughout the lockdown, which is crucial for preventing anxiety and depression [59, 60]. Fourth, our studies cannot control for unmeasured confounding, for example, different capacities to respond to the life changes (“resilience”) among students. Finally, although the longitudinal design showed the strength of associations between these risk factors and depression/anxiety symptoms, we lack the detailed information on when the exposures and outcomes occur and were unable to estimate the incidence rates. Future studies using more objective and comprehensive measures on students’ life changes, including both potential risk and protective factors, as well as utilization of approaches or experimental designs that could strengthen a causal relationship, are warranted for our findings’ replication and generalizability.