Epidemiology

Depressive disorders are very common and are among the leading causes of disability and excess mortality worldwide.[17][18][19][20]​​​​​​ In people aged 15-29 years, depression is the leading cause of disability and premature death globally. WHO: Global Health Estimates Opens in new window​ In the US, major depression is the second leading cause of disability overall.[21] Beyond the direct impact of depression itself on occupational function and quality of life, depression is associated with poorer health outcomes across several conditions.[22][23][24]

It has been estimated that around 4.7% of the world’s population will experience an episode of depression in any 12-month time period.[25] One international study carried out in 2019 found that point prevalence was highest in North America (4.4% for women and 2.5% for men), lowest in the Western Pacific (2.3% for women and 1.3% for men) and intermediate in other world areas (2.8% to 3.6% for women, and 1.9% to 2.0% for men). IHME: Global Burden of Disease (GBD) Opens in new window​ In 2015, the World Health Organization (WHO) found a relatively higher 12-month prevalence than this for people living in Africa compared to in other locations globally (5.8% for women, and 4.8% for men).[17] Other studies suggest more substantial variation in reported prevalence between countries, from 2% to 21%, depending on the particular country.[26]​ Within Europe, prevalence rates vary substantially between countries; higher rates of prevalence have been identified in Germany, Luxembourg and Iceland, with lower rates identified in Slovakia and the Czech Republic.​[27] Methodological differences are believed to account for at least some of this reported variability across populations.

Mean age of onset is 26 years in high-income countries, and 24 in low- and middle-income countries, according to World Mental Health survey data.[28]​ Prevalence peaks again in later life.[29]​ Global prevalence in older adults has been estimated at 13.3%.[30]​ Prevalence may be higher amongst older people who are hospitalised or living in assisted care facilities.[31]​ About one in five nursing home residents without dementia are diagnosed with depression.[32]​ One systematic review looking at rates of depression in older adults globally, estimated the pooled prevalence of depression in older adults as being 31.74%, with higher rates of depression in this age group seen within developing countries (40.78%) compared to developed countries (17.05%).[31]

Incidence in women is double the incidence in men.​[27][33]

People with depression experience an almost 20-fold risk of dying by suicide than do the general population.[34]​ One meta-analysis found that 31% of people in treatment for major depressive disorder had attempted suicide in their lifetime.[35]

Comorbidity with other mental health conditions is common across treatment settings in both primary and secondary care, particularly with anxiety disorders, post-traumatic stress disorder and substance use disorders.[36][37]​​ Men with depression are twice as likely as women to have a comorbid substance use disorder.[38]

In patients with an affected first-degree relative, the lifetime risk of depression increases two- to threefold. First onset occurs most frequently in patients aged 12-24 years or older than 65 years.[39]

Depression frequently coexists with a large number of chronic physical health disorders, including chronic pain, cardiovascular disease, cancer, diabetes, chronic respiratory diseases, tuberculosis, and obesity, potentially as a result of shared risk factors and also due to the causal effect of the physical disorder on the development of depression.[40]​ Dementia, by some measures, can nearly double the risk.[41]​ It has been postulated that depression itself may act as a causal risk factor for the development and worsening of some chronic physical disorders.[42][43][44][45]​​

The prevalence of major depressive disorder increased rapidly during the COVID-19 pandemic, particularly in younger adults.[46][47][48] The World Health Organization (WHO) estimates that the COVID-19 pandemic triggered a 25% increase in the prevalence of depression worldwide; the longer-term implications of this are currently unclear.[49]

Use of this content is subject to our disclaimer