British Medical JournalComparison of Mental Health Symptoms Before and During the COVID-19 Pandemic: Evidence from a Systematic Review and Meta-analysis of 134 Cohorts

Many studies have a high risk of bias and significant heterogeneity, implying that results should be interpreted with caution. Nonetheless, most estimates of symptom change for general mental health, anxiety symptoms, and depression symptoms were close to zero and not statistically significant, and significant changes were of minimal to minor magnitudes. In all domains, women or female participants experienced minor negative changes.