Changes in Mental Health Symptoms

Methods Notes: Eligible studies must report changes in symptom levels, proportion of participants above a cutoff threshold, or proportion of participants who change by a pre-defined magnitude (e.g., minimal clinically important difference) across a delineated COVID-19 related event. This could include comparisons of pre-COVID-19 and COVID-19 symptoms, symptoms at the initiation of the outbreak to the peak, or symptoms during highly restrictive isolation periods to subsequent periods, for instance. Studies with < 100 participants are excluded.


We are not including cross-sectional studies that report percentages of participants with scores above cutoff thresholds on commonly used symptom questionnaires. Conclusions that can be drawn from that type of data about mental health effects from COVID-19 and clinical implications, however, are limited, and, per our protocol, we have not included those studies. This is because percentages of people who score above a threshold on standardized questionnaires vary, sometimes dramatically, between populations, even in normal times. For example, the percentage of participants with scores of at least 10 on the Patient-Health Questionnaire-9,[1] a commonly used measure of depressive symptoms, in large, randomly selected, regional or national general population samples, has been reported as 4% in Hong Kong (N = 6,028);[2] 6% in Germany (N = 5,018);[3] 7% in Shanghai, China (N = 1,045);[4] 8% in the United States (N = 10,257);[5] 8% in the province of Alberta, Canada (N = 3,304);[6] 11% in Sweden (N = 3,001);[7] and 22% in Jiangsu Province, China (N = 8,400).[8] Even within populations from the same region, the percentage can vary dramatically depending on sample characteristics. In Jiangsu Province, for example, the percentage among rural residents (32%) is twice that of urban residents (16%); it is also several times higher for older adults (25% for 55-64 years; 87% for ≥ 65 years) than for young adults (8% for 18-34 years).[8] Further complicating interpretation when there is not a time-based or other relevant comparator, percentages from symptom measures such as the PHQ-9 tend to dramatically overestimate prevalence that would be obtained from validated methods for ascertaining prevalence of mental health disorders, and there is too much heterogeneity between samples in the difference to correct for this statistically.[9]
Summary of Results: Nine studies have compared mental health symptoms prior to and during COVID-19; four of the studies were on undergraduate students (7890, 7899, 18242, 19533), three (17066, 21717, 9941) were from population-based surveys, one (24680) surveyed 435 people with a rare pre-existing medical condition in Canada, the United Kingdom, the United States, and France, and one (23486) surveyed 2288 sexual and gender minority people in the United States. The four studies of university students were from Switzerland, China, and the United States (N = 2); they included between 178 and 555 participants. The three populated-based studies included samples from the United Kingdom (N=2), the United States, Canada, Ireland, and Brazil; they included between 218 and 12,090 participants.


Among studies of undergraduate students, in study 7890, which included 209 undergraduate students from Switzerland, symptoms of depression increased by 0.53 (0.33 to 0.72) standard deviations, stress by 0.40 (0.20 to 0.59), loneliness by 0.29 (0.10 to 0.49), and symptoms of anxiety by 0.17 (-0.02 to 0.37). A second study (7899), of 178 undergraduate students from the United States reported that there were statistically significant changes in symptoms of both anxiety and depression, but it did not report data that allowed estimation of effect size; regression estimates of changes in depression symptoms, though, were substantially larger than those for anxiety. Another study from the United States, with 487 undergraduates, found that anxiety symptoms decreased significantly, though by a small amount, from the beginning of the semester and prior to COVID-19 to the end of the semester during COVID-19 (0.17 standard deviations, 95% CI 0.04 to 0.31). In the study from China, there were small increases in combined anxiety and depressive symptoms and in negative affect.

Among population studies, in study 17066, which recruited large random population samples from the UK (N=12,090), there was a small increase in general mental health symptoms of 0.31 standard deviations (95% CI 0.29 to 0.34; 1 point on GHQ – dichotomized items). It was not possible to determine, though, the relative changes in anxiety and depressive symptoms. Study 21717, which recruited a small international sample via the online Prolific Academic platform (N=218), reports negligible changes in anxiety (-0.11 standard deviations, 95% CI -0.30 to 0.08), depression (0.08 standard deviations, 95% CI -0.11 to 0.27), rumination (-0.07 standard deviations, 95% CI -0.25 to 0.12), and distress (-0.09 standard deviations, 95% CI -0.28 to 0.10). Study 9941 showed that among participants in Brazil (N=360), there were small increases in depression (0.20 standard deviations, 95% CI 0.05 to 0.34), anxiety (0.30 standard deviations, 95% CI 0.15 to 0.45), and stress (0.22 standard deviations, 95% CI 0.07 to 0.37). The study did not report how participants were recruited.

Study 24680 surveyed a well-characterized, international cohort of people with the rare disease systemic sclerosis (N= 388-435).  There was a large increase in anxiety (0.51 standard deviations, 95% CI 0.37 to 0.64) and a negligible decrease in depression (-0.05 standard deviations, 95% CI -0.19 to 0.09). 

In a well-characterized cohort of sexual and gender minority people in the United States (N=2,288), study 23486 reported a small increase in depression (0.19 standard deviations, 95% CI 0.14 to 0.25) and a large increase in anxiety (0.54 standard deviations, 95% CI 0.48 to 0.60). 

Comment: Among university students for whom social relationships are likely highly valued and for whom risk of complications from COVID-19 is generally lower than among other adults, symptoms of depression increased more than anxiety in two studies where that was reported; in a third study, anxiety symptoms actually decreased among university students. The large population study in the UK reported general mental health symptoms and a small increase, but this did not allow interpretation of the types of symptoms experiences. The additional two population studies show either small increases or negligible changes in anxiety, depression, and other mental health functions. Emerging evidence on vulnerable populations suggests anxiety may be more important. The study in the rare disease cohort showed a large increase in anxiety while there were negligible changes in depression. The study on sexual and gender minority people indicated a similarly large increase in anxiety and a small increase in depression. It will be important to understand to what degree these finding are replicated in other university students and vulnerable populations. 


1.    Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606-613.
2.    Yu X, Tam WWS, Wong PTK, Lam TH, Stewart SM. The Patient Health Questionnaire-9 for measuring depressive symptoms among the general population in Hong Kong. Compr Psychiatry. 2012;53:95-102.
3.    Kocalevent RD, Hinz A, Brähler E. Standardization of the depression screener Patient Health Questionnaire (PHQ-9) in the general population. Gen Hosp Psychiatry. 2013;35:551-555.
4.    Wang W, Bian Q, Zhao Y, et al. Reliability and validity of the Chinese version of the Patient Health Questionnaire (PHQ-9) in the general population. Gen Hosp Psychiatry. 2014;36:539-544.
5.    Cao C, Hu L, Xu T, et al. Prevalence, correlates, and misperception of depression symptoms in the United States, NHANES 2015-2018. J Affect Disord. 2020;269:51-57.
6.    Patten SB, Schopflocher D. Longitudinal epidemiology of major depression as assessed by the Brief Patient Health Questionnaire (PHQ-9). Compr Psychiatry. 2009;50:26-33.
7.    Johansson R, Carlbring P, Heedman A, Paxling B, Andersson G. Depression, anxiety and their comorbidity in the Swedish general population: point prevalence and the effect on health-related quality of life. PeerJ. 2013;1:e98.
8.    Lu S, Reavley N, Zhou J, et al. Depression among the general adult population in Jiangsu Province of China: prevalence, associated factors and impacts. Soc Psychiatry Psychiatr Epidemiol. 2018;53:1051-1061.
9.    Levis B, Benedetti A, Ioannidis JPA, et al. Patient Health Questionnaire-9 scores do not accurately estimate depression prevalence: an individual participant data meta-analysis. J Clin Epidemiol. 2020;122:115-128.





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*Abbreviations: CES-D= Center for Epidemiologic Studies Depression Scale; DASS-21= Depression, Anxiety, and Stress Scale; DToS= Distress Tolerance Scale; FDI= Filgueiras Depression Inventory; GAD-7= Generalized Anxiety Disorder; GHQ= General Health Questionnaire; PANAS= Positive and Negative Affect Schedule; PHQ= Patient Health Questionnaire; PROMIS= Patient Reported Outcomes Measurement Information System; PSS= Perceived Stress Scale; RRQ= Reflection and Rumination Scale; STAI= State Trait Anxiety Inventory; ULS-9= University of California, Los Angeles (UCLA) Loneliness Scale

*A positive effect size indicates an increase in the construct assessed





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