OBJECTIVES : An estimated 264 million individuals suffer from depression globally. However, there may be substantial under-reporting of depression experience/symptoms related to social taboos, discrimination, personal values, or lack of support. This study aims to uncover the global hidden burden of depression.

METHODS : Data from the National Health and Wellness Survey were analysed for China (2017), Japan, the US (2019), France, Germany, the UK, Italy, Spain (collectively EU5), and Brazil (2018). Depression severity (none, mild, moderate, moderately-severe, severe) was measured using the Patient Health Questionnaire-9 for individuals in each country, stratified by self-reported experience of depression. Descriptive statistics are reported as frequencies.

RESULTS : Rates of individuals screening for all-levels depression (mild to severe) in the total population were 37.9% in the US, 40.9% in EU5, 43.7% in Brazil, 25.8% in Japan, and 38.7% in China. Among individuals screening for all-levels depression, 48.6% in the US, 65.9% in EU5, 69.7% in Brazil, 86% in Japan, and 92.2% in China did not report experiencing depression. There was a trend in which consistently more people in Japan and China did not report experiencing depression despite screening for it across levels, compared to the US, EU5, and Brazil. Importantly, among those screening for severe depression, 59.4% in Japan and 76.1% in China did not report experiencing depression, compared to 50.2% in the US, 29.5% in EU5, and 42.5% in Brazil.

CONCLUSIONS : Among individuals screening depression, rates of self-reported depression were lowest in China and Japan. This population represents a potentially vulnerable group unaware of the severity of their symptoms, who may be at increased risk for depression-related poor health outcomes, social isolation, and self-harm. These findings highlight the necessity of ensuring appropriate depression screening and preventive measures, as well as adequate mental health services, are available.